CN109876809A

CN109876809A - A kind of composite metal oxide hollow multi-shell material and its preparation method and use

Info

Publication number: CN109876809A
Application number: CN201910257038.XA
Authority: CN
Inventors: 王丹; 魏延泽; 万家炜
Original assignee: Institute of Process Engineering of CAS
Current assignee: Institute of Process Engineering of CAS
Priority date: 2019-04-01
Filing date: 2019-04-01
Publication date: 2019-06-14
Anticipated expiration: 2039-04-01
Also published as: CN109876809B

Abstract

The invention provides a composite metal oxide hollow multi-shell material, a preparation method and application thereof, and the method comprises: using carbon spheres prepared by a hydrothermal method as a template, dispersing the carbon spheres in a first metal salt solution, The solid precursor is obtained after hydrothermally enhanced adsorption and drying; the obtained solid precursor is dispersed in the second metal salt solution, adsorbed and calcined to obtain the composite metal oxide hollow multi-shell material. In the invention, through the two-step adsorption method, the relative content of the narrow-bandgap metal oxide attached to the inner shell of the metal oxide hollow sphere is high, and the relative content of the wide-bandgap metal oxide attached to the outer shell is high, so as to achieve high relative content of the solar spectrum. The sequential absorption of light in each wavelength band.

Description

A kind of hollow more Shell Materials of metal composite oxide and its preparation method and application

Technical field

The invention belongs to technical field of function materials, it is related to a kind of more Shell Materials of metal oxide hollow, its preparation side Method and purposes, more particularly to a kind of hollow more Shell Materials of metal composite oxide for capableing of order absorption solar spectrum, its system Preparation Method and the photochemical catalyst for being used for photocatalysis Decomposition aquatic products hydrogen.

Background technique

More shell hollow micron/nanostructures have light large specific surface area, density, special internal cavity structure and by low The features such as adjustable shell wall of wiener rice grain or nanometer bar construction, thus all realize and be widely used in many fields, than Such as medicament slow release, catalysis, sensor, water pollution control, nano-reactor and energy-storage system.Wherein, it is applied to photocatalysis The multilayered structure in field, the more shell hollow sphere complexity of metal oxide allows incident light Multiple Scattering in ball, effectively prolongs Optical path has been grown, capture of the entire material to light is enhanced, has been conducive to more multi-photon and participates in electronics in metal-oxide semiconductor (MOS) Excitation process.In addition, the more effective ratio area that the more shell hollow spheres of metal oxide provide, is conducive to reactant and is urging The absorption on agent surface further enhances its reactivity as catalyst.

Currently, the preparation method of more shell oxide hollow spheres mainly has soft template method and two kinds of hard template method.Soft template Method refers in the solution, using micella or emulsion droplet as template, chemically reacts, is finally separating dry in two-phase interface It is dry, hollow microsphere is prepared.The soft template method reported at present is only applicable to the preparation of the more shell hollow spheres of specific compound, and The product form uniformity of synthesis is poor, needs to prepare reversed phase micelle or reverse micro emulsion using a large amount of organic solvent, uncomfortable Close large-scale production, it is difficult to which there is universality.Hard template method refers to micro- with monodispersed inorganic matter, high molecular polymer or resin Nanoparticle deposits various chemical materials as template, on its surface, then takes out template by calcining or solvent extraction, is formed equal One hollow ball material.The core-shell material of hard template method preparation with monodispersity, stablize by good, repeatable high and product form Etc. advantages, obtain the extensive concern of researcher.

CN102464304A discloses a kind of more shell-layer metal oxide hollow balls and preparation method thereof, utilizes hydro-thermal legal system Standby carbon ball template；Metal salt is dissolved in carbon ball suspension, by modulation metal salt concentrations, solution ph, soaking temperature and when Between equal adsorption conditions, control metal salt enters the quantity, depth and gradient distribution of carbon ball；To adsorbed the carbon ball of metal ion into Row heat treatment, can be obtained more shell-layer metal oxide hollow balls.The hollow sphere prepared using this method, shell is by metal oxygen The nanocrystal of compound is accumulated, shell number can between two to four layers modulation, the size and shell thickness of hollow sphere Control.The method of the present invention is simple and easy, controllability is high, pollution is small, it is at low cost and have universality.Prepared product has hollow Structure and thickness are in the shell of nanoscale, while multilayered structure can efficiently use inner space, urge applied to air-sensitive and light Change, it is shown that compare Conventional nano material and the superior performance of single layer hollow sphere.

CN103247777A discloses a kind of more shell hollow sphere cathode materials of the cobaltosic oxide applied to lithium ion battery Material and preparation method thereof.Using the carbon ball of hydro-thermal method preparation as template, by controlling the ratio of water and ethyl alcohol in cobalt salt solution, The temperature of solution and the adsorption capacity of carbon ball are prepared to control the quantity of cobalt ions in carbon ball and its enter depth Single, double, triple and four shell cobaltosic oxide hollow spheres.But more shell hollow spheres of this method preparation are for making lithium ion battery Negative electrode material, photochemical catalyst field application there are still limitations.

Currently, for more shell hollow spheres, for light-catalysed research, there has also been certain progress, such as more shells two The research (Nanoscale, 2014,6,4072) that cerium oxide hollow sphere photochemical catalytic oxidation water prepares oxygen proves more shell titanium dioxides Cerium hollow sphere shows the light absorpting ability beyond nano particle, to realize more efficient photodissociation aquatic products oxygen performance.

However, further utilizing advantage of more shell hollow spheres in nano-space scale depth, each layer of controlledly synthesis The research of more shell hollow spheres with different component and function still lacks.Therefore, how to provide a kind of with pervasive extensively The method of property, can control the biggish metal oxide of band gap and be in outer shell, weak for absorbing penetration capacity in solar spectrum Ultraviolet portion, the lesser metal oxide of band gap is in hypostracum, for absorb penetration capacity in solar spectrum it is strong can Light-exposed part absorbs the light order of wave band each in solar spectrum to realize, improves the utilization to sunlight, and then obtain Efficient photocatalysis performance has become current urgent problem to be solved.

Summary of the invention

In view of the deficiencies of the prior art, the present invention intends to provide a kind of hollow more shells of metal composite oxide Layer material, preparation method and use are adsorbed by two steps, there is significantly different metal ions in the carbon ball template after making absorption Concentration gradient, to obtain the hollow more Shell Materials of metal composite oxide that energy order absorbs solar spectrum after baking.

To achieve this purpose, the present invention adopts the following technical scheme:

In a first aspect, the present invention provides a kind of preparation method of the hollow more Shell Materials of metal composite oxide, it is described Method includes:

(1) it using the carbon ball of hydro-thermal method preparation as template, disperses carbon ball in the first metal salt solution, hydro-thermal enhancing Solid precursor is obtained after absorption, drying；

(2) it disperses the solid precursor that step (1) obtains in the second metal salt solution, absorption, roasting obtain described The hollow more Shell Materials of metal composite oxide；

Wherein, the hydrated ionic radius in first metal salt solution is less than the hydration in second metal salt solution Ionic radius.

In the method, the presoma selection of metal oxide is extremely important, and the present invention is by selecting different hydrated ions The metal salt solution of radius is as precursor solution, and different metal ions generate apparent concentration in the carbon ball template after making absorption Gradient.Firstly, in step (1) by dispersion and hydro-thermal enhance adsorption operations so that have smaller hydrated ionic radius and institute it is right The lesser metal ion of metal oxide band gap answered can deeper into be adsorbed onto inside carbon ball；By dividing in step (2) Scattered and adsorption operations, make to have larger hydrated ionic radius and the corresponding biggish metal ion of metal oxide band gap are main It is gathered in carbon ball surface, the narrow band gap metal oxidation that the hypostracum of the metallic oxide hollow sphere obtained after baking in this way contains Object relative amount is high, and the broad-band gap metal oxide relative amount of outer shell is high.When being applied to photocatalysis field, outside The weak ultraviolet portion of penetration capacity in the absorbable solar spectrum of the broad-band gap metal oxide of shell layer surface aggregation, and hypostracum The narrow metal oxide of adsorption can absorb the visible light part that penetration capacity is strong in solar spectrum, to realize to sunlight The light order of each wave band absorbs in spectrum.

As currently preferred technical solution, it is molten that first metal salt solution is selected from copper nitrate solution, copper chloride Liquid, copper-bath, tetrachloro close copper acid solution, cupric tetramminosulfate, iron nitrate solution, ferric chloride solution, cobalt nitrate solution, chlorine Change the combination of one of cobalt liquor and cobalt acetate solution or at least two, preferably copper nitrate solution, copper chloride solution, sulfuric acid One of copper solution, ferric nitrate, cobalt nitrate or at least two combination；The first metal salt solution that the present invention selects for The metal salt of smaller hydrated ionic radius, corresponding metal oxide have lesser forbidden bandwidth, the lesser metal of band gap Oxide is in hypostracum, for absorbing the strong visible light part of penetration capacity in solar spectrum.

" hydro-thermal method " of the present invention, which refers to for carbon containing precursor water solution to be fitted into reaction kettle, carries out hydro-thermal reaction, warp Cool down, be filtered, washed, dry after obtain the method for carbon ball template, compared with traditional mechanical attrition method, prepared by hydro-thermal method Carbon ball uniform particle sizes, size is controllable, while a large amount of active function groups are contained on surface, and there is excellent hydrophily and surface to react Activity, the more conducively absorption of metal ion are the common templates for preparing Core-shell structure material.

" hydro-thermal enhancing absorption " of the present invention, which refers to, is fitted into carbon ball template and metal salt solution in reaction kettle, hydro-thermal Absorption of the enhancing carbon ball template to metal ion under state obtains after cooling, centrifugation, washing, drying rich in the first metal The method of the solid precursor of salt ion.

Preferably, the solvent of first metal salt solution is selected from or mixtures thereof water, ethyl alcohol, and preferred solvent is water.

Preferably, it is molten to be selected from titanium tetrachloride solution, titanium tetrabromide solution, titanium tetra iodide for second metal salt solution Liquid, fluorination titanium solution, solution of tetrabutyl titanate, isopropyl titanate solution, titanyl sulfate solution, zinc nitrate solution, zinc chloride are molten One of liquid, cerous nitrate solution and solution of cerium chloride by oxidation or at least two combination, preferably titanium tetrachloride solution, four fourth of metatitanic acid One of ester solution, isopropyl titanate solution, zinc nitrate, cerous nitrate or at least two combination；The present invention select second Metal salt solution is the metal salt with larger hydrated ionic radius, and corresponding metal oxide has biggish forbidden band wide Degree, the biggish metal oxide of band gap is in outer shell, for absorbing the weak ultraviolet portion of penetration capacity in solar spectrum.

Preferably, the solvent of second metal salt solution is selected from or mixtures thereof water, ethyl alcohol, and preferred solvent is water.

As currently preferred technical solution, the preparation method packet of the hollow more Shell Materials of metal composite oxide It includes:

(a) carbon source aqueous solution is fitted into reaction kettle and carries out hydro-thermal reaction, obtain carbon ball mould after being filtered, washed and dried drying Plate；

(b) it disperses the carbon ball template that step (a) obtains in the first metal salt solution, through hydro-thermal enhancing absorption, drying After obtain the first solid precursor；

(c) the first solid precursor for obtaining step (b) is scattered in the second metal salt solution, after being adsorbed, being dried Obtain the second solid precursor；

(d) the second solid precursor for obtaining step (c) roasts, and it is hollow to obtain the metal composite oxide More Shell Materials.

As currently preferred technical solution, carbon source described in step (a) is glucose, fructose, sucrose, malt One of sugar, starch or citric acid or at least two combination, preferably sucrose.

Preferably, in the carbon source aqueous solution carbon source concentration be 0.1-6M, such as can be 0.1M, 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M, 4M, 4.5M, 5M, 5.5M or 6M, preferably 1-5M, further preferred 2-3M.

Preferably, the hydro-thermal reaction carries out in a kettle.

Preferably, the temperature of the hydro-thermal reaction is 175-220 DEG C, such as can be 175 DEG C, 180 DEG C, 185 DEG C, 190 DEG C, 195 DEG C or 200 DEG C, preferably 190-205 DEG C, further preferably 195-200 DEG C.

Preferably, the time of the hydro-thermal reaction be 100-180min, such as can be 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min or 180min, preferably 120-140min, further preferably 125- 135min。

Preferably, it is washed using one of deionized water, methanol or ethyl alcohol or any two kinds of combination, such as can To be the combination of deionized water, methanol, ethyl alcohol, deionized water and methanol, the combination of deionized water and ethyl alcohol or methanol and ethyl alcohol Combination.

Preferably, the washing times are 2-5 times, such as be can be 2 times, 3 times, 4 times or 5 times, preferably 3-4 times.

Preferably, the temperature of the drying is 60-100 DEG C, such as can be 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C, 80 DEG C, 85 DEG C, 90 DEG C, 95 DEG C or 100 DEG C, preferably 70-90 DEG C, further preferably 75-85 DEG C.

Preferably, the time of the drying be 6-24h, such as can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or for 24 hours, preferably 15-24h, further preferably 18-20h.

As currently preferred technical solution, the concentration of the first metal salt solution described in step (b) is 0.01- 0.5M, such as can be 0.01M, 0.1M, 0.15M, 0.2M, 0.25M, 0.3M, 0.35M, 0.4M, 0.45M or 0.5M, preferably 0.05-0.2M, further preferably 0.1-0.15M.

Preferably, described to be adsorbed as hydro-thermal enhancing absorption.

Preferably, hydro-thermal enhancing adsorption temp is 100-160 DEG C, for example, can be 100 DEG C, 110 DEG C, 120 DEG C, 130 DEG C, 140 DEG C, 150 DEG C or 160 DEG C, preferably 120-160 DEG C, further preferably 130-150 DEG C.

Preferably, the adsorption time is 1-6h, such as can be 1h, 2h, 3h, 4h, 5h or 6h, preferably 2-5h, into one Walk preferred 3-4h.

Preferably, the mixed liquor obtained after absorption to absorption is centrifuged, and is taken out lower layer's solid, is washed.

Preferably, the temperature of the drying is 60-100 DEG C, such as can be 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C, 80 DEG C, 85 DEG C, 90 DEG C, 95 DEG C or 100 DEG C, preferably 70-90 DEG C, further preferred 75-85 DEG C.

Preferably, the time of the drying be 6-24h, such as can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or for 24 hours, preferably 15-24h, further preferred 18-20h.

As currently preferred technical solution, the concentration of the second metal salt solution described in step (c) is 1-5M, example It such as can be 1M, 1.5M, 2M, 2.5M, 3M, 3.5M, 4M, 4.5M or 5M, preferably 1-3M, further preferably 1.5-2.5M.

Preferably, described to be adsorbed as stirring and adsorbing.

Preferably, the adsorption temp be 20-60 DEG C, such as can be 20 DEG C, 25 DEG C, 30 DEG C, 35 DEG C, 40 DEG C, 45 DEG C, 50 DEG C, 55 DEG C or 60 DEG C, preferably 30-50 DEG C, further preferred 35-45 DEG C.

Preferably, the adsorption time be 4-24h, such as can be 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or for 24 hours, preferably 8-20h, further preferred 10-18h.

Preferably, the mixed liquor obtained after absorption to absorption is filtered and is cleaned.

Preferably, the wash number is 2-5 times, such as be can be 2 times, 3 times, 4 times or 5 times, preferably 3-4 times.

Preferably, the scavenging period be 0.5-24h, such as can be 2h, 4h, 6h, 8h, 10h, 11h, 14h, 16h, 18h, 20h, 22h or for 24 hours, preferably 5-20h, further preferred 10-15h.

Preferably, the drying temperature is 60-100 DEG C, such as can be 60 DEG C, 65 DEG C, 70 DEG C, 75 DEG C, 80 DEG C, 85 DEG C, 90 DEG C, 95 DEG C or 100 DEG C, preferably 70-90 DEG C, further preferred 75-85 DEG C.

Preferably, the drying time be 6-24h, such as can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or for 24 hours, preferably 15-24h, further preferably 18-20h.

As currently preferred technical solution, roasting described in step (d) in Muffle furnace, tube furnace or kiln into Row.

Preferably, the maturing temperature be 400-800 DEG C, such as can be 400 DEG C, 450 DEG C, 500 DEG C, 550 DEG C, 600 DEG C, 650 DEG C, 700 DEG C, 750 DEG C or 800 DEG C, preferably 450-600 DEG C, further preferred 500-550 DEG C.

Preferably, the time of the roasting be 0.5-10h, such as can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h or 10h, preferably 1-2h, it is further excellent Select 1.2-1.8h.

Preferably, the heating rate of the roasting be 0.5-10 DEG C/min, such as can be 0.5 DEG C/min, 1 DEG C/min, 1.5℃/min、2℃/min、2.5℃/min、3℃/min、3.5℃/min、4℃/min、4.5℃/min、5℃/min、5.5 ℃/min、6℃/min、6.5℃/min、7℃/min、7.5℃/min、8℃/min、8.5℃/min、9℃/min、9.5℃/ Min or 10 DEG C/min, preferably 0.5-1 DEG C/min, further preferred 0.6-0.8 DEG C/min.

Preferably, the atmosphere of the roasting is air and/or oxygen, preferably air or oxygen, the present invention by using Oxygen atmosphere calcining, accelerates the crystallization of metal oxide and the combustion decomposition of carbon ball, generates bulk gas and impacts shell wall, is prepared into The internal metal oxide hollow structure with a plurality of cavities is arrived.

In the preparation process in accordance with the present invention, step (a) and step (b) 1-5 times can be repeated before roasting, to obtain shell The hollow more Shell Materials of metal composite oxide between layer 2-4.

The present invention by adjusting the concentration of two kinds of metal salts with different hydrated ionic radius, inhale by adsorption temp, repetition The synthesis conditions such as attached number, calcination atmosphere can make the content of different metal oxides in shell change, to realize not Specific absorption is generated with light of the shell to different wave length, further realizes and the effect that order absorbs is generated to white light in solar spectrum It answers, enhances the absorbing ability of prepared more shell hollow sphere photochemical catalysts, and then improve its photocatalysis efficiency.

As currently preferred technical solution, which comprises

(a) the carbon source aqueous solution that concentration is 0.1-6M is fitted into hydro-thermal reaction 100- in 175-220 DEG C of reaction kettle 180min is filtered after natural cooling, and after 2-5 washing, by product at 60-100 DEG C dry 6-24h, obtain carbon ball mould Plate；

(b) it disperses the carbon ball template that step (a) obtains in the first metal salt solution that concentration is 0.01-0.5M, In the first metal salt solution be copper nitrate solution, copper chloride solution, copper-bath, tetrachloro close copper solution, cupric tetramminosulfate Solution, iron nitrate solution, one of ferric chloride solution, cobalt nitrate solution, cobalt chloride solution and cobalt acetate solution or at least two The combination of kind, hydro-thermal adsorbs 1-6h at 100-160 DEG C, and the mixed liquor after absorption is centrifuged, and takes out lower layer's solid, uses deionization Water, methanol or ethanol washing 2-5 times, dry 6-24h, obtains the first solid precursor at 60-100 DEG C；

(c) the first solid precursor for obtaining step (b) is scattered in the second metal salt solution that concentration is 1-5M, In, the second metal salt solution is titanium tetrachloride solution, titanium tetrabromide solution, titanium tetra iodide solution, fluorination titanium solution, four fourth of metatitanic acid Ester solution, isopropyl titanate solution, titanyl sulfate solution, zinc nitrate solution, liquor zinci chloridi, cerous nitrate solution and cerium chloride are molten One of liquid or at least two combination, filtered after stirring and adsorbing 4-24h at 20-60 DEG C, with deionized water, methanol or second Alcohol washs 2-5 times, washs 0.5-24h, and dry 6-24h, obtains the second solid precursor at 60-100 DEG C；

(d) the second solid precursor for obtaining step (c) is placed in the atmosphere in Muffle furnace or kiln in air or oxygen Middle roasting 0.5-10h, maturing temperature are 400-800 DEG C, and heating rate is 0.5-10 DEG C/min, obtain the compound gold after cooling Belong to the hollow more Shell Materials of oxide.

Second aspect, the present invention provides a kind of metal composite oxides that preparation method as described in relation to the first aspect obtains Hollow more Shell Materials, the hollow more Shell Materials of metal composite oxide include at least one cavity and at least one layer of shell Wall, wherein wall surface accumulation there are two types of or two or more metal oxide nanoparticles or nanometer rods.

Preferably, the shell wall is 2~4 layers, such as can be 2 layers, 3 layers or 4 layers.

Preferably, the band gap of the metal oxide of the housing wall surface accumulation is greater than the metal oxygen of inner casing wall surface accumulation The band gap of compound.

Preferably, the shell wall energy order absorbs solar spectrum.

Preferably, the order is absorbed as the ultraviolet portion in shell wall absorption solar spectrum, and inner wall absorbs too Visible light part in solar spectrum.

The third aspect, the present invention provides a kind of photochemical catalyst, the photochemical catalyst includes answering as described in second aspect Close the more Shell Materials of metal oxide hollow.

Preferably, the photochemical catalyst can be contained under the irradiation of 300W xenon lamp with the production hydrogen resolution of velocity of 70mmol/h/g There is the water-methanol mixed solution of 25% volume fraction.

The hollow more stronger light absorpting abilities of Shell Materials of the metal composite oxide that the present invention is prepared, more shells are multiple Miscellaneous multilevel structure also can significantly extend the optical circuit path for injecting catalyst.In addition, the characteristics of more shells itself, makes to be catalyzed Agent has bigger specific surface area, keeps contact of the catalyst with reaction solution more abundant, and above-mentioned hollow sphere is applied to photocatalysis The photochemical catalyst for decomposing aquatic products hydrogen can be realized to the absorption of the order of solar spectrum, can be under the irradiation of 300W xenon lamp The production hydrogen resolution of velocity of 70mmol/h/g contains the water-methanol mixed solution of 25% volume fraction, and can obtain more than 90h's Reaction stability, performance are significantly larger than the nano particle of same composition.

Numberical range of the present invention not only includes enumerated point value, further includes the above-mentioned numerical value not included Arbitrary point value between range, as space is limited and for concise consideration, range described in the present invention no longer exclusive list includes Specific point value.

Compared with prior art, the invention has the benefit that

1, the invention proposes being adsorbed by two steps, hydro-thermal enhancing absorption hydrated ionic radius is smaller first and corresponding gold Belong to the lesser metal ion of oxide band gap, then adsorbs that hydration radius is larger and the corresponding biggish metal of metal oxide band gap Ion makes different metal ions in the carbon ball template after adsorbing have apparent concentration gradient, to obtain compound gold after baking Belong to the hollow more Shell Materials of oxide.By the obtained more shell oxide hollow spheres of absorption calcining can be realized outer shell for The relatively strong of the weak short wavelength UV area light of penetration power absorbs, and the relatively strong of the hypostracum wavelength visible area strong for penetration power is inhaled It receives.

2, the hollow more Shell Materials of metal composite oxide that the present invention is prepared have stronger light absorpting ability, more The multilevel structure of shell complexity also can significantly extend the optical circuit path for injecting catalyst.In addition, the characteristics of more shells itself Make catalyst that there is bigger specific surface area, keeps contact of the catalyst with reaction solution more abundant, multi-stage porous can also be conducive to The transmission of liquids and gases.Above-mentioned hollow sphere is applied to the photochemical catalyst of photocatalysis Decomposition aquatic products hydrogen, can be realized to the sun The order of spectrum absorbs, and can contain 25% volume fraction under the irradiation of 300W xenon lamp with the production hydrogen resolution of velocity of 70mmol/h/g Water-methanol mixed solution, and the reaction stability more than 90h can be obtained, performance is significantly larger than the nanometer of same composition Particle.

Detailed description of the invention

Fig. 1 is four shell TiO prepared by embodiment 1₂-Cu_xThe transmission electron microscope photo of O hollow sphere.

Fig. 2 is three shell TiO prepared by embodiment 2₂-Cu_xThe transmission electron microscope photo of O hollow sphere.

Fig. 3 a is more shell TiO prepared by embodiment 1₂-Cu_xThe slice of O hollow sphere transmits photo figure.

Fig. 3 b is more shell TiO prepared by embodiment 1₂-Cu_xThe TEM-EDX linear sweep graph of O hollow sphere.

Fig. 4 is the uv-visible absorption spectrum figure of the monoshell layer of different Ti/Cu ratios.

Fig. 5 is more shell TiO prepared by embodiment 1₂-Cu_xTiO prepared by O hollow sphere and comparative example 1₂-Cu_xO nanometers The uv-visible absorption spectrum figure of grain.

Wherein, solid line TiO₂-Cu_xO hollow sphere；Dotted line is TiO₂-Cu_xO nano particle.

Fig. 6 a is more shell TiO prepared by embodiment 1₂-Cu_xThe cyclical stability figure of the photochemical catalyzing of O hollow sphere.

Fig. 6 b is more shell TiO prepared by embodiment 1₂-Cu_xTiO prepared by O hollow sphere and comparative example 1₂-Cu_xO nanometers The performance comparison figure of grain photochemical catalyzing.

Fig. 7 is more shell TiO prepared by embodiment 2₂-Cu_xThe X-ray diffractogram of O hollow sphere.

Specific embodiment

To further illustrate the technical scheme of the present invention below with reference to the accompanying drawings and specific embodiments.

Embodiment 1

A kind of preparation method of the hollow more Shell Materials of metal composite oxide, which comprises

(1) aqueous sucrose solution that concentration is 1.5M is fitted into hydro-thermal reaction 135min in 200 DEG C of reaction kettle, natural cooling After filter, and through water washing 3 times, place the product in 60 DEG C of baking ovens it is dry for 24 hours, obtain the carbon ball template that diameter is 2.9 μm；

(2) CuCl that 30mL concentration is 0.1M is dispersed by the carbon ball template that step (1) obtains₂In solution, ultrasound makes carbon Ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 4h in 120 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken out Lower layer's solid is washed with deionized 3 times, is put into drying in 60 DEG C of baking ovens and for 24 hours, obtains the first solid precursor；

(3) TiCl that concentration is 3M is dispersed by the first solid precursor that step (2) obtains₄In solution, at 40 DEG C Stirring and adsorbing filters afterwards for 24 hours, is washed with deionized 3 times, is put into drying in 60 DEG C of baking ovens and obtains the second solid precursor for 24 hours；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 2 DEG C/min 450 DEG C, constant temperature calcining 2h, four shell TiO are obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.8 μm.

The transmission electron microscope photo of product is as shown in Figure 1, be outermost two layers four adjacent shell hollow spheres.Fig. 3 a is shown pair Hollow sphere carries out the transmission electron microscope photo for the sample that embedded section obtains.The scanning of TEM-EDX line is carried out to the sample after slice, such as Shown in Fig. 3 b, it is seen that the ratio of Ti element and Cu element has obvious gap on different shells.Outer layer Ti/Cu ratio about It for 15:1, and is about 6:1 in hypostracum Ti/Cu ratio.Compare the extinction energy of single shell hollow sphere of two kinds of difference Ti/Cu ratios Power, as shown in figure 4, the monoshell layer that Ti/Cu ratio is about 15:1 will be apparently higher than Ti/Cu ratio in the absorbability of ultraviolet region The monoshell layer of about 6:1.Meanwhile the absorbing ability of monoshell layer in visible region Ti/Cu ratio being about 6:1 wants more excellent.It is comprehensive Absorption of the different shells to the light of different wave length is closed, shown in Fig. 5, is capable of the metal composite oxide of order absorption solar spectrum Hollow more Shell Materials show more excellent absorbing ability than nano particle in full spectrum.And as shown in Figure 6 b, exist The lower water-methanol mixing that can contain 25% volume fraction with the production hydrogen resolution of velocity of 70mmol/h/g of 300W xenon lamp irradiation is molten Liquid, and can stablize circulate beyond 90h as shown in Figure 6 a.

Embodiment 2

(1) aqueous sucrose solution that concentration is 1.5M is fitted into hydro-thermal reaction 130min in 200 DEG C of reaction kettle, natural cooling After filter, and through water washing 3 times, place the product in 70 DEG C of baking ovens it is dry for 24 hours, obtain the carbon ball template that diameter is 2.7 μm；

(2) CuCl that 30mL concentration is 0.2M is dispersed by the carbon ball template that step (1) obtains₂In solution, ultrasound makes carbon Ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 2h in 140 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken out Lower layer's solid is washed with deionized 3 times, is put into 70 DEG C of baking ovens dry 12h, obtains the first solid precursor；

(3) TiCl that concentration is 3M is dispersed by the first solid precursor that step (2) obtains₄In solution, at 60 DEG C It filters, is washed with deionized 3 times after stirring and adsorbing 12h, be put into 70 DEG C of baking ovens dry 12h and obtain the second solid precursor；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 2 DEG C/min 450 DEG C, constant temperature calcining 1h, four shell TiO are obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.8 μm.

The transmission electron microscope photo of product is as shown in Fig. 2, be the hollow sphere of three shell structurres.By the X-ray diffractogram of Fig. 7 Spectrum, analysis know to be made of titanium dioxide anatase and Rutile Type.It can be with 50mmol/h/g under the irradiation of 300W xenon lamp Production hydrogen resolution of velocity contain the water-methanol mixed solution of 25% volume fraction.

Embodiment 3

(1) aqueous sucrose solution that concentration is 1.5M is fitted into hydro-thermal reaction 130min in 200 DEG C of reaction kettle, natural cooling After filter, and through water and ethanol washing 3 times, place the product in 12h dry in 60 DEG C of baking ovens, obtain the carbon ball that diameter is 2.7 μm Template；

(2) Cu (NO that 30mL concentration is 0.1M is dispersed by the carbon ball template that step (1) obtains₃)₂In solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 1h in 160 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into drying in 60 DEG C of baking ovens and for 24 hours, obtains the first solid precursor；

(3) TiCl that concentration is 2M is dispersed by the first solid precursor that step (2) obtains₄In solution, at 25 DEG C It filters, is washed with deionized 3 times after stirring and adsorbing 18h, be put into drying in 60 DEG C of baking ovens and obtain the second solid precursor for 24 hours；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 5 DEG C/min 450 DEG C, constant temperature calcining 1h, bivalve layer TiO is obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.6 μm.

Embodiment 4

(1) aqueous sucrose solution that concentration is 2M is fitted into hydro-thermal reaction 120min in 180 DEG C of reaction kettle, after natural cooling It filters, and through water and ethanol washing 3 times, place the product in 12h dry in 80 DEG C of baking ovens, obtain the carbon ball template that diameter is 3 μm；

(2) Cu (NO that 30mL concentration is 0.3M is dispersed by the carbon ball template that step (1) obtains₃)₂In solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 6h in 100 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into drying in 60 DEG C of baking ovens and for 24 hours, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the isopropyl titanate solution that concentration is 1M, 35 Stirring and adsorbing filters afterwards for 24 hours at DEG C, is washed with deionized 3 times, is put into 80 DEG C of baking ovens dry 12h and obtains the second solid forerunner Body；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 1 DEG C/min 500 DEG C, constant temperature calcining 1h, three shell TiO are obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.8 μm.

Embodiment 5

(1) aqueous sucrose solution that concentration is 1.5M is fitted into hydro-thermal reaction 130min in 200 DEG C of reaction kettle, natural cooling After filter, and through water and ethanol washing 3 times, place the product in 12h dry in 80 DEG C of baking ovens, obtain the carbon ball that diameter is 2.7 μm Template；

(2) Cu (NO that 30mL concentration is 0.5M is dispersed by the carbon ball template that step (1) obtains₃)₂In aqueous solution, ultrasound So that carbon ball is uniformly dispersed, be packed into reaction kettle, is placed in hydro-thermal enhancing absorption 2h in 100 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, Lower layer's solid is taken out, is washed with deionized 3 times, drying in 60 DEG C of baking ovens is put into and for 24 hours, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the isopropyl titanate solution that concentration is 2M, 30 It filters, is washed with deionized 3 times after stirring and adsorbing 12h at DEG C, be put into 80 DEG C of baking ovens dry 12h and obtain the second solid forerunner Body；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 2 DEG C/min 550 DEG C, constant temperature calcining 1h, three shell TiO are obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.8 μm.

Embodiment 6

(1) aqueous sucrose solution that concentration is 1.5M is fitted into hydro-thermal reaction 133min in 200 DEG C of reaction kettle, natural cooling After filter, and through water and ethanol washing 3 times, place the product in 12h dry in 80 DEG C of baking ovens, obtain the carbon ball that diameter is 3.1 μm Template；

(2) CuCl that 30mL concentration is 0.2M is dispersed by the carbon ball template that step (1) obtains₂In aqueous solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 2h in 100 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into 100 DEG C of baking ovens dry 15h, obtains the first solid precursor；

(3) TiF that concentration is 1M is dispersed by the first solid precursor that step (2) obtains₄In solution, stirred at 30 DEG C It filters, is washed with deionized 3 times after mixing absorption 6h, be put into 80 DEG C of baking ovens dry 12h and obtain the second solid precursor；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 1 DEG C/min 450 DEG C, constant temperature calcining 1h, bivalve layer TiO is obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 1 μm.

Embodiment 7

(1) glucose solution that concentration is 0.1M is fitted into hydro-thermal reaction 100min in 175 DEG C of reaction kettle, it is naturally cold But it filters afterwards, and through water and ethanol washing 2 times, place the product in 6h dry in 60 DEG C of baking ovens, obtain the carbon ball mould that diameter is 3 μm Plate；

(2) it disperses the carbon ball template that step (1) obtains in the ferric chloride in aqueous solution that 30mL concentration is 0.01M, ultrasound So that carbon ball is uniformly dispersed, be packed into reaction kettle, is placed in hydro-thermal enhancing absorption 1h in 100 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, Lower layer's solid is taken out, is washed 2 times with methanol, dry 6h is put into 60 DEG C of baking ovens, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the zinc nitrate solution that concentration is 1M, at 20 DEG C It filters, is washed with deionized 3 times after stirring and adsorbing 4h, be put into 60 DEG C of baking ovens dry 6h and obtain the second solid precursor；

(4) the second solid precursor that step (3) obtains is placed in tube furnace, in air with 0.5 DEG C/min heating To 400 DEG C, constant temperature calcining 0.5h, four shell ZnO-Fe are obtained after natural cooling₂O₃Hollow sphere, shell size are about 0.7 μm.

Embodiment 8

(1) the fructose aqueous solution that concentration is 1M is fitted into hydro-thermal reaction 120min in 190 DEG C of reaction kettle, after natural cooling It filters, and through water and ethanol washing 3 times, place the product in 15h dry in 70 DEG C of baking ovens, obtain the carbon ball mould that diameter is 2.5 μm Plate；

(2) tetrachloro that 30mL concentration is 0.05M is dispersed by the carbon ball template that step (1) obtains to close in copper aqueous acid, Ultrasound makes carbon ball be uniformly dispersed, and is packed into reaction kettle, hydro-thermal enhancing absorption 2h in 120 DEG C of baking ovens is placed in, by the mixed liquor after absorption Centrifugation is taken out lower layer's solid, is washed with deionized 3 times, is put into 70 DEG C of baking ovens dry 15h, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the zinc nitrate solution that concentration is 1M, at 30 DEG C It filters, is washed with deionized 3 times after stirring and adsorbing 8h, be put into 70 DEG C of baking ovens dry 15h and obtain the second solid precursor；

(4) the second solid precursor that step (3) obtains is placed in kiln, is warming up in oxygen with 0.5 DEG C/min 450 DEG C, constant temperature calcining 1h, bivalve layer ZnO-Cu is obtained after natural cooling_xO hollow sphere, shell size are about 0.6 μm.

Embodiment 9

(1) aqueous sucrose solution that concentration is 2M is fitted into hydro-thermal reaction 125min in 195 DEG C of reaction kettle, after natural cooling It filters, and through water and ethanol washing 3 times, place the product in 18h dry in 75 DEG C of baking ovens, obtain the carbon ball mould that diameter is 2.6 μm Plate；

(2) it disperses the carbon ball template that step (1) obtains in the cobalt nitrate aqueous solution that 30mL concentration is 0.1M, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 3h in 130 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into 75 DEG C of baking ovens dry 18h, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the solution of cerium chloride by oxidation that concentration is 1.5M, at 35 DEG C It is filtered after lower stirring and adsorbing 10h, with ethanol washing 3 times, is put into 75 DEG C of baking ovens dry 18h and obtains the second solid precursor；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, in air with 0.6 DEG C/min heating To 500 DEG C, constant temperature calcining 1.2h, bivalve layer CeO is obtained after natural cooling₂-Co₃O₄Hollow sphere, shell size are about 0.5 μm.

Embodiment 10

(1) maltose solution that concentration is 3M is fitted into hydro-thermal reaction 135min in 200 DEG C of reaction kettle, natural cooling After filter, and through water and ethanol washing 3 times, place the product in 20h dry in 85 DEG C of baking ovens, obtain the carbon ball that diameter is 3.1 μm Template；

(2) CuCl that 30mL concentration is 0.15M is dispersed by the carbon ball template that step (1) obtains₂In aqueous solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 4h in 150 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into 85 DEG C of baking ovens dry 20h, obtains the first solid precursor；

(3) it disperses the first solid precursor that step (2) obtains in the cerous nitrate solution that concentration is 2.5M, at 45 DEG C It filters, is washed with deionized 3 times after lower stirring and adsorbing 18h, be put into 85 DEG C of baking ovens dry 20h and obtain the second solid forerunner Body；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, in air with 0.8 DEG C/min heating To 550 DEG C, constant temperature calcining 1.8h, three shell CeO are obtained after natural cooling₂-Cu_xO hollow sphere, shell size are about 0.7 μm.

Embodiment 11

(1) amidin that concentration is 5M is fitted into hydro-thermal reaction 140min in 205 DEG C of reaction kettle, after natural cooling It filters, and through water and ethanol washing 3 times, place the product in dryings in 90 DEG C of baking ovens for 24 hours, obtains the carbon ball mould that diameter is 3.3 μm Plate；

(2) CoCl that 30mL concentration is 0.2M is dispersed by the carbon ball template that step (1) obtains₂In aqueous solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 5h in 160 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into drying in 70 DEG C of baking ovens and for 24 hours, obtains the first solid precursor；

(3) TiCl that concentration is 3M is dispersed by the first solid precursor that step (2) obtains₄In solution, at 50 DEG C It filters, is washed with deionized 3 times after stirring and adsorbing 20h, be put into drying in 90 DEG C of baking ovens and obtain the second solid precursor for 24 hours；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 1 DEG C/min 600 DEG C, constant temperature calcining 2h, four shell TiO are obtained after natural cooling₂-Co₃O₄Hollow sphere, shell size are about 0.8 μm.

Embodiment 12

(1) aqueous citric acid solution that concentration is 6M is fitted into hydro-thermal reaction 180min in 220 DEG C of reaction kettle, natural cooling After filter, and through water and ethanol washing 3 times, place the product in 100 DEG C of baking ovens it is dry for 24 hours, obtain the carbon ball that diameter is 3.4 μm Template；

(2) FeCl that 30mL concentration is 0.5M is dispersed by the carbon ball template that step (1) obtains₃In aqueous solution, ultrasound makes Carbon ball is uniformly dispersed, and is packed into reaction kettle, is placed in hydro-thermal enhancing absorption 6h in 100 DEG C of baking ovens, the mixed liquor after absorption is centrifuged, is taken Lower layer's solid out is washed with deionized 3 times, is put into drying in 100 DEG C of baking ovens and for 24 hours, obtains the first solid precursor；

(3) TiF that concentration is 5M is dispersed by the first solid precursor that step (2) obtains₄In solution, stirred at 60 DEG C It mixes absorption to filter afterwards for 24 hours, be washed with deionized 3 times, be put into drying in 100 DEG C of baking ovens and obtain the second solid precursor for 24 hours；

(4) the second solid precursor that step (3) obtains is placed in Muffle furnace, is warming up in air with 10 DEG C/min 800 DEG C, constant temperature calcining 10h, four shell TiO are obtained after natural cooling₂-Fe₂O₃Hollow sphere, shell size are about 0.7 μm.

Comparative example 1

A certain proportion of butyl titanate and copper nitrate are mixed and are placed in Muffle furnace, is warming up to 400 with 1 DEG C/min DEG C, calcining at constant temperature 1h is washed with deionized 3 times after natural cooling, is put into 100 DEG C of baking ovens dry 15h, obtains TiO₂-Cu_xO Nano particle, size are about 100-300nm.

By absorbing more shells and nano particle in light absorpting ability and photocatalysis Decomposition aquatic products about order in Fig. 5, Fig. 6 Comparison in Hydrogen Energy power finds four shell TiO₂-Cu_xO hollow sphere will be substantially better than TiO in the absorbing ability of full spectral region₂- Cu_xO nano particle.The hollow more Shell Materials of the metal composite oxide being prepared by the present invention realize that outer shell absorption penetrates The weak ultraviolet light of ability, hypostracum absorb the strong visible light of penetration capacity, and furthermore the special pattern advantage of more shells provides more Big specific surface area and reaction site, TiO₂-Cu_xO hollow sphere has shown obvious more excellent photocatalytic water hydrogen production potential, The lower water-methanol mixing that can contain 25% volume fraction with the production hydrogen resolution of velocity of 70mmol/h/g of 300W xenon lamp irradiation is molten Liquid, and recycling can be stablized more than 90h.

Comparative example 2

The difference from embodiment 1 is that carbon ball template is prepared by the high-frequency collision of ball mill steel ball and solid carbon black, His operating parameter is same as Example 1, and monoshell layer TiO is prepared₂-Cu_xO hollow sphere, shell size are about 0.5 μm.Comprehensive point Analysis embodiment 1 and comparative example 1 it is found that using hydro-thermal method prepare carbon ball template can preferably reach technical effect of the invention, This is because the carbon ball template sphericity of mechanical attrition method preparation is poor, particle size uniformity is bad, and surface lacks enough reactions The effect of group, adsorbing metal ions is undesirable, can only obtain size monoshell unevenly distributed after roasting to presoma Layer hollow sphere.

The Applicant declares that the foregoing is merely a specific embodiment of the invention, but protection scope of the present invention not office It is limited to this, it should be clear to those skilled in the art, any to belong to those skilled in the art and take off in the present invention In the technical scope of dew, any changes or substitutions that can be easily thought of, and all of which fall within the scope of protection and disclosure of the present invention.

Claims

1. a preparation method of composite metal oxide hollow multi-shell material, is characterized in that, described method comprises:

(1) using the carbon ball prepared by the hydrothermal method as a template, dispersing the carbon ball in the first metal salt solution, and obtaining a solid precursor after hydrothermally enhanced adsorption and drying;

(2) dispersing the solid precursor obtained in step (1) in the second metal salt solution, adsorbing and calcining to obtain the composite metal oxide hollow multi-shell material;

Wherein, the hydrated ion radius in the first metal salt solution is smaller than the hydrated ion radius in the second metal salt solution.

2. preparation method according to claim 1, is characterized in that, described first metal salt solution is selected from cupric nitrate solution, cupric chloride solution, copper sulfate solution, tetrachloro cupric acid solution, tetraammine sulfate One or a combination of at least two in copper solution, ferric nitrate solution, ferric chloride solution, cobalt nitrate solution, cobalt chloride solution and cobalt acetate solution, preferably copper nitrate solution, copper chloride solution, ferric nitrate solution, One or a combination of at least two of cobalt nitrate;

Preferably, the solvent of the first metal salt solution is selected from water, ethanol or a mixture thereof, preferably the solvent is water;

Preferably, the second metal salt solution is selected from titanium tetrachloride solution, titanium tetrabromide solution, titanium tetraiodide solution, titanium fluoride solution, tetrabutyl titanate solution, isopropyl titanate solution, One or a combination of at least two of titanium oxysulfate solution, zinc nitrate solution, zinc chloride solution, cerium nitrate solution and cerium chloride solution, preferably titanium tetrachloride solution, tetrabutyl titanate solution, titanic acid One or a combination of at least two of isopropyl ester solution, zinc nitrate solution and cerium nitrate solution;

Preferably, the solvent of the second metal salt solution is selected from water, ethanol or a mixture thereof, preferably the solvent is water.

3. preparation method according to claim 1 and 2, is characterized in that, described method comprises:

(a) the carbon source aqueous solution is loaded into the reactor to carry out hydrothermal reaction, and the carbon ball template is obtained after filtration, washing and drying;

(b) dispersing the carbon sphere template obtained in step (a) in the first metal salt solution, performing enhanced adsorption to the first metal salt ion under hydrothermal conditions, and drying to obtain the first solid precursor;

(c) dispersing the first solid precursor obtained in step (b) in the second metal salt solution, and obtaining the second solid precursor after adsorption and drying;

(d) calcining the second solid precursor obtained in step (c) to obtain the composite metal oxide hollow multi-shell material.

4. preparation method according to claim 3 is characterized in that, the carbon source described in step (a) is one or the combination of at least two in glucose, fructose, sucrose, maltose, starch or citric acid, preferably sucrose;

Preferably, the concentration of the carbon source in the carbon source aqueous solution is 0.1-6M, preferably 1-5M, more preferably 2-3M;

Preferably, the hydrothermal reaction is carried out in a reactor;

Preferably, the temperature of the hydrothermal reaction is 175-220°C, preferably 190-205°C, more preferably 195-200°C;

Preferably, the time of the hydrothermal reaction is 100-180min, preferably 120-140min, more preferably 125-135min;

Preferably, one or a combination of any two of deionized water, methanol or ethanol is used for washing;

Preferably, the washing times are 2-5 times, preferably 3-4 times;

Preferably, the drying temperature is 60-100°C, preferably 70-90°C, more preferably 75-85°C;

Preferably, the drying time is 6-24h, preferably 15-24h, more preferably 18-20h.

5. The preparation method according to claim 3 or 4, wherein the concentration of the first metal salt solution described in the step (b) is 0.01-0.5M, preferably 0.05-0.2M, more preferably 0.1 -0.15M;

Preferably, the adsorption is hydrothermal adsorption;

Preferably, the adsorption temperature is 100-160°C, preferably 120-160°C, more preferably 130-150°C;

Preferably, the adsorption time is 1-6h, preferably 2-5h, more preferably 3-4h;

Preferably, after the adsorption, the mixed solution obtained by the adsorption is centrifuged, and the lower layer solid is taken out and washed;

Preferably, the washing times are 2-5 times, preferably 3-4 times;

6. The preparation method according to any one of claims 3-5, wherein the concentration of the second metal salt solution described in the step (c) is 1-5M, preferably 1-3M, more preferably 1.5-2.5M;

Preferably, the adsorption is stirring adsorption;

Preferably, the adsorption temperature is 20-60°C, preferably 30-50°C, more preferably 35-45°C;

Preferably, the adsorption time is 4-24h, preferably 8-20h, more preferably 10-18h;

Preferably, suction filtration and cleaning are performed on the mixed solution obtained by adsorption after adsorption;

Preferably, one or a combination of any two of deionized water, methanol or ethanol is used for cleaning;

Preferably, the cleaning times are 2-5 times, preferably 3-4 times;

Preferably, the cleaning time is 0.5-24h, preferably 5-20h, more preferably 10-15h;

7. The preparation method according to any one of claims 3-6, wherein the roasting described in step (d) is carried out in a muffle furnace, a tubular furnace or a kiln;

Preferably, the roasting temperature is 400-800°C, preferably 450-600°C, more preferably 500-550°C;

Preferably, the roasting time is 0.5-10h, preferably 1-2h, more preferably 1.2-1.8h;

Preferably, the heating rate of the roasting is 0.5-10°C/min, preferably 0.5-1°C/min, more preferably 0.6-0.8°C/min;

Preferably, the firing atmosphere is air and/or oxygen, preferably air or oxygen.

8. The preparation method according to any one of claims 3-7, wherein the method comprises:

(a) a carbon source aqueous solution with a concentration of 0.1-6M is charged into a reactor at 175-220° C. for hydrothermal reaction for 100-180min, suction filtration after natural cooling, and after 2-5 washings, the product is placed in a 60- Dry at 100°C for 6-24h to obtain a carbon sphere template;

(b) dispersing the carbon sphere template obtained in step (a) in a first metal salt solution with a concentration of 0.01-0.5M, wherein the first metal salt solution is copper nitrate solution, copper chloride solution, copper sulfate solution, four One or a combination of at least two of copper chloride solution, tetraammine copper sulfate solution, ferric nitrate solution, ferric chloride solution, cobalt nitrate solution, cobalt chloride solution and cobalt acetate solution, in water at 100-160°C Heat adsorption for 1-6h, centrifuge the adsorbed mixture, take out the lower solid, wash with deionized water, methanol or ethanol for 2-5 times, and dry at 60-100°C for 6-24h to obtain the first solid precursor;

(c) dispersing the first solid precursor obtained in step (b) in a second metal salt solution with a concentration of 1-5M, wherein the second metal salt solution is a titanium tetrachloride solution, a titanium tetrabromide solution, One of titanium tetraiodide solution, titanium fluoride solution, tetrabutyl titanate solution, isopropyl titanate solution, titanium oxysulfate solution, zinc nitrate solution, zinc chloride solution, cerium nitrate solution and cerium chloride solution One or a combination of at least two, stirring and adsorbing at 20-60°C for 4-24h, suction filtration, washing with deionized water, methanol or ethanol for 2-5 times, washing for 0.5-24h, and drying at 60-100°C for 6 -24h, the second solid precursor is obtained;

(d) placing the second solid precursor obtained in step (c) in a muffle furnace or a kiln and calcining in an atmosphere of air or oxygen for 0.5-10h, the calcining temperature is 400-800°C, and the heating rate is 0.5-10 ℃/min, and the composite metal oxide hollow multi-shell material is obtained after cooling.

9. The composite metal oxide hollow multi-shell layer material obtained by the preparation method according to any one of claims 1-8, wherein the composite metal oxide hollow multi-shell layer material comprises at least one cavity and at least one cavity. A layer of shell wall, wherein two or more metal oxide nanoparticles or nanorods are deposited on the surface of the shell wall;

Preferably, the shell wall is 2-4 layers;

Preferably, the band gap of the metal oxide deposited on the surface of the outer shell wall is larger than the band gap of the metal oxide deposited on the surface of the inner shell wall;

Preferably, the shell wall can sequentially absorb the solar spectrum;

Preferably, the sequential absorption is that the outer shell wall absorbs the ultraviolet light part of the solar spectrum, and the inner shell wall absorbs the visible light part of the solar spectrum.

10. A photocatalyst for photocatalytic decomposition of water to produce hydrogen, wherein the photocatalyst comprises the composite metal oxide hollow multi-shell material according to claim 9;

Preferably, the photocatalyst can decompose a water-methanol mixed solution containing 25% volume fraction at a hydrogen production rate of 70 mmol/h/g under the irradiation of a 300W xenon lamp.