CN114198850B - Gas-solid phase electrocatalytic electrode and preparation method and application thereof - Google Patents

Abstract

The invention provides a gas-solid phase electrocatalytic electrode and its preparation method and application. The gas-solid phase electrocatalytic electrode comprises a conductive substrate, an anodic oxidation active layer and a hydrophilic solid electrolyte layer which are sequentially stacked. The gas-solid phase electrocatalytic electrode provided by the present invention is modified with a hydrophilic solid electrolyte, the electron transfer rate in the gas-solid phase reaction is accelerated, the activation ability of water is significantly improved, and it has good performance on indoor pollutants. The catalytic oxidation ability is simple, and the preparation method is simple, and the operation is simple and easy to realize automation.

Description

A gas-solid phase electrocatalytic electrode and its preparation method and application

technical field

The invention belongs to the technical field of electrocatalysis and relates to a gas-solid phase electrocatalysis electrode and its preparation method and application.

Background technique

People spend 80% of their lives indoors. With the acceleration of urbanization, people's requirements for indoor air quality continue to increase, and new requirements are also placed on indoor air purification technology. Indoor pollutants such as formaldehyde and VOCs are not only highly irritating and toxic, but also have triple effects, which are extremely harmful to human health. Supported noble metal catalysts can effectively degrade formaldehyde at room temperature, but they are expensive and difficult for practical large-scale application. Benzene series, etc. cannot be degraded at room temperature because of their stable structure. Therefore, there is an urgent need to develop catalysts that can degrade indoor pollutants at room temperature and have a broad spectrum. The electrocatalytic oxidation method has become a very promising technology because of its high processing efficiency, simple operation and easy automation.

CN100450610C discloses a supported manganese-cerium oxide catalyst, the active component of which is silver, gold or platinum; the molar ratio of Mn/Ce in the manganese-cerium composite oxide is 1.0, and the loading capacity of the active component is manganese-cerium oxide 0.1 to 5% of the weight of the product. The main steps of the preparation method are: suspending manganese-cerium composite oxide powder in an aqueous solution, adding soluble silver, gold or platinum solution under stirring to prepare silver, gold or platinum manganese-cerium oxide powder suspension; in step d Add KOH or K ₂ CO ₃ solution to the floating liquid respectively to make the pH value equal to 9-10, precipitate and filter; dry the precipitate obtained in step e at 80-120°C, and roast at 300-500°C for 2-10 hours to obtain target product.

CN101380574A discloses a highly selective catalyst for catalyzing the complete oxidation of low-concentration formaldehyde at room temperature. The catalyst can completely catalyze the conversion of formaldehyde into carbon dioxide and water at room temperature, and the conversion rate of formaldehyde remains at 100% for a long time, without the need for complex auxiliary equipment and external conditions such as light sources and heating furnaces. The catalyst consists of three parts: porous inorganic oxide carrier, precious metal component and auxiliary agent component. The porous inorganic oxide carrier is one or more mixtures of ceria, zirconia, titanium dioxide, aluminum oxide, tin dioxide, silicon dioxide, lanthanum oxide, magnesium oxide, and zinc oxide, or Its composite oxide, zeolite, sepiolite, porous carbon material; the catalyst precious metal component is at least one of platinum, rhodium, palladium, gold, silver, and the additive component is alkali metal lithium, sodium, potassium, rubidium, At least one of cesium.

Although the above two documents can completely oxidize and decompose formaldehyde into CO ₂ and H ₂ O at room temperature, the higher efficiency is mostly concentrated on the noble metal platinum catalyst, and the indoor high humidity atmosphere is not considered, and the supported noble metal catalyst is expensive , The actual large-scale application is difficult.

Therefore, how to provide a catalyst that can effectively remove indoor pollutants at room temperature is an urgent technical problem to be solved.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a gas-solid phase electrocatalytic electrode and its preparation method and application. The gas-solid-phase electrocatalytic electrode provided by the present invention is modified with a hydrophilic-based solid electrolyte, the electron transfer rate in the gas-solid phase reaction is accelerated, the activation ability of water is significantly improved, and it has good performance on indoor pollutants. The catalytic oxidation ability is simple, and the preparation method is simple, and the operation is simple and easy to realize automation.

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a gas-solid-phase electrocatalytic electrode, which comprises a conductive substrate, an anodic oxidation active layer and a hydrophilic-based solid electrolyte layer that are sequentially stacked.

The gas-solid-phase electrocatalytic electrode provided by the present invention is modified with a hydrophilic-based solid electrolyte, the electron transfer rate in the gas-solid phase reaction is accelerated, the activation ability of water is significantly improved, and it has good performance on indoor pollutants. catalytic oxidation capacity.

The hydrophilic-based solid electrolyte in the present invention means that the solid-state electrolyte contains hydrophilic groups.

The gas-solid phase electrocatalytic electrode provided by the invention is suitable for the gas-solid phase reaction of double electrodes.

If the gas-solid phase electrocatalytic electrode provided by the present invention uses a solid electrolyte layer that does not contain a hydrophilic group, sufficient activation of active sites cannot be achieved, and a conductive network cannot be formed.

Preferably, the anodic oxidation active layer comprises an oxidation active oxide.

Preferably, the oxidation active oxide comprises SnO ₂ and/or PbO ₂ .

Preferably, the loading amount of the oxidation active oxide is 10-100 mg/cm ² , such as 10 mg/cm ² , 20 mg/cm ² , 30 mg/cm ² , 40 mg/cm ² , 50 mg/cm ² , 60 mg/cm ² , 70mg/cm ² , 80mg/cm ² , 90mg/cm ² or 100mg/cm ² , etc.

The loading provided by the present invention is the mass distribution of the substances in the active layer on the conductive substrate.

Preferably, the conductive substrate includes any one or a combination of at least two of metal foam, metal mesh or carbon paper.

Preferably, the thickness of the hydrophilic-based solid electrolyte layer is 2-500 μm, such as 2 μm, 10 μm, 20 μm, 50 μm, 100 μm, 130 μm, 150 μm, 180 μm, 200 μm, 230 μm, 250 μm, 280 μm, 300 μm, 330 μm, 350 μm, 380 μm , 400μm, 430μm, 450μm, 480μm or 500μm, etc.

In the present invention, if the thickness of the hydrophilic-based solid electrolyte layer is too small, it is not conducive to the formation of the conductive network and the full activation of the active sites, and if the thickness is too large, the conductive resistance of the system will increase too much.

In a second aspect, the present invention provides a method for preparing a gas-solid phase electrocatalytic electrode as described in the first aspect, the preparation method comprising the following steps:

preparing a catalyst precursor with an anodic oxidation active layer on the surface of the conductive substrate, and then coating a hydrophilic-based solid electrolyte solution on the surface of the anodic oxidation active layer to obtain the catalyst.

The preparation method provided by the invention is simple in operation, without adopting complex technical solutions, and can obtain a gas-solid phase catalyst electrode with high catalytic oxidation activity through simple coating.

Preferably, the concentration of the hydrophilic-based solid electrolyte solution is 1 to 50%, such as 1%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 40%, 45%, or 50%, etc., preferably 5 to 35%.

In the present invention, if the concentration of the hydrophilic-based solid electrolyte solution is less than 1%, it is not conducive to the enrichment of the solid electrolyte on the surface of the active material, and if it is greater than 50%, it will cause an increase in the conductive resistance; and further adjusted to When it is in the range of 5% to 35%, it has the advantage of ensuring that an appropriate amount of hydrophilic-based solid electrolyte is properly enriched on the active surface.

Preferably, the amount of the hydrophilic solid electrolyte solution is 0.1-1mL/cm ² , such as 0.1mL/cm ² , 0.2mL/cm ² , 0.3mL/cm ² , 0.4mL/cm ² , 0.5mL/cm 2 ² , 0.6mL/cm ² , 0.7mL/cm ² , 0.8mL/cm ² , 0.9mL/cm ² or 1mL/cm ² , etc.

Preferably, the hydrophilic-based solid electrolyte includes any one or at least two of polystyrene-based solid electrolytes, perfluorosulfonic acid solid electrolytes, polyallylamine hydrochloride, polyacrylamide or polyamide epichlorohydrin A combination of species, preferably perfluorosulfonic acid solid electrolyte and/or polystyrenesulfonic acid

Preferably, the preparation method of the catalyst precursor of the anodic oxidation active layer provided on the surface of the conductive substrate comprises:

The oxidation active oxide is arranged on the surface of the conductive substrate by coating or electrodeposition.

As a preferred technical solution, the preparation method comprises:

The oxidative active oxide is arranged on the surface of the conductive substrate by coating or electrodeposition, and after drying, a catalyst precursor with an anodic oxidation active layer on the surface of the conductive substrate is obtained, and then a hydrophilic-based solid electrolyte with a mass concentration of 5-35% is applied The solution is coated on the surface of the anodic oxidation active layer in an amount of 0.1-1 mL/cm ² and dried to obtain the catalyst.

In the third aspect, the present invention also provides the use of a gas-solid phase electrocatalytic electrode, which includes using the gas-solid phase electrocatalytic electrode as described in the first aspect for electrochemical catalytic oxidation of indoor pollutants.

Ordinary gas-solid-phase electrocatalytic electrodes have poor electrocatalytic performance, and when applied to electrocatalytic degradation of benzene series, 15% _CO2 will be generated and cannot degrade indoor pollutants such as formaldehyde. The gas-solid-phase electrocatalytic electrode provided by the present invention. The activity is significantly increased, and it can degrade various indoor pollutants such as toluene and formaldehyde, and has a broad spectrum

Preferably, the indoor pollutants include various indoor pollutants such as formaldehyde and benzene series

Compared with the prior art, the present invention has the following beneficial effects:

The gas-solid-phase electrocatalytic electrode provided by the present invention is modified with a hydrophilic-based solid electrolyte, the electron transfer rate in the gas-solid phase reaction is accelerated, the activation ability of water is significantly improved, and it has good performance on indoor pollutants. Catalytic oxidation ability, and the preparation method is simple, easy to operate and easy to realize automation, the mass concentration of the hydrophilic solid electrolyte is in the range of 5 to 35%, when the gas-solid electrocatalytic electrode provided by the present invention is used to catalyze the oxidation of toluene , degraded for 1 hour, the removal rate of toluene can be over 70%, and the conversion rate of _{CO 2 can} be over 90%. %above.

Detailed ways

The technical solutions of the present invention will be further described below through specific examples. It should be clear to those skilled in the art that the examples are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

This embodiment provides a gas-solid phase electrocatalytic electrode, the gas-solid phase electrocatalytic electrode includes a conductive substrate, an anodic oxidation active layer, and a hydrophilic solid electrolyte layer that are sequentially stacked;

The conductive substrate is foamed Ti, the anodic oxidation active layer is SnO ₂ layer, the SnO ₂ in the SnO ₂ layer The load capacity is 45mg/cm ² , the hydrophilic solid electrolyte layer is perfluorosulfonic acid solid electrolyte (Nafion), The thickness of the hydrophilic-based solid electrolyte layer was 40 μm.

The preparation method of the gas-solid phase electrocatalytic electrode is as follows:

The _SnO2 slurry is coated on the surface of the conductive substrate, and after drying, the catalyst precursor of the anodic oxidation active layer is obtained on the ^surface of the conductive substrate, and then the mass concentration is 10% of the hydrophilic solid electrolyte solution in an amount of 0.5mL/cm coating on the surface of the anodic oxidation active layer and drying to obtain the catalyst.

Example 2

This embodiment provides a gas-solid phase electrocatalytic electrode, the gas-solid phase electrocatalytic electrode includes a conductive substrate, an anodic oxidation active layer, and a hydrophilic solid electrolyte layer that are sequentially stacked;

The conductive substrate is Ni foam, the anodic oxidation active layer is a _PbO2 layer, the loading capacity of _PbO2 in the _PbO2 layer is 10mg/ ^cm2 , the hydrophilic-based solid electrolyte layer is Nafion, and the thickness of the hydrophilic-based solid electrolyte layer is is 150 μm.

The preparation method of the gas-solid phase electrocatalytic electrode is as follows:

_PbO2 is arranged on the surface of the conductive substrate by electrodeposition, and after drying, the catalyst precursor of the anodic oxidation active layer is obtained on the surface of the conductive substrate, and then the mass concentration is 5% of the hydrophilic solid electrolyte solution at 0.1mL/cm ² The amount of the catalyst is coated on the surface of the anodic oxidation active layer and dried to obtain the catalyst.

Example 3

This embodiment provides a gas-solid phase electrocatalytic electrode, the gas-solid phase electrocatalytic electrode includes a conductive substrate, an anodic oxidation active layer, and a hydrophilic solid electrolyte layer that are sequentially stacked;

The conductive substrate is carbon paper, the anodic oxidation active layer is a SnO ₂ layer, the loading capacity of SnO ₂ in the SnO ₂ layer is 100 mg/cm ² , the hydrophilic solid electrolyte layer is sodium polystyrene sulfonate, and the hydrophilic base The thickness of the solid electrolyte is 50 μm.

The preparation method of the gas-solid phase electrocatalytic electrode is as follows:

The _SnO2 slurry is coated on the surface of the conductive substrate, and after drying, the catalyst precursor of the anodic oxidation active layer is obtained on the surface of the conductive substrate, and then the hydrophilic solid electrolyte solution with a mass concentration of 35% is coated with the ^amount of 1mL/cm Cover the surface of the anodic oxidation active layer and dry to obtain the catalyst.

Example 4

The difference between this embodiment and Embodiment 1 is that the mass concentration of the hydrophilic-based solid electrolyte solution in this embodiment is 1%.

All the other preparation methods and parameters are consistent with Example 1.

Example 5

The difference between this embodiment and Embodiment 1 is that the mass concentration of the hydrophilic-based solid electrolyte solution in this embodiment is 50%.

All the other preparation methods and parameters are consistent with Example 1.

Comparative example 1

The difference between this comparative example and Example 1 is that the gas-solid phase electrocatalytic electrode provided in this comparative example does not contain a hydrophilic-based solid electrolyte layer.

In the preparation method, obtaining the catalyst precursor is obtaining the gas-solid phase electrocatalytic electrode.

All the other preparation methods and parameters are consistent with Example 1.

Comparative example 2

The difference between this comparative example and Example 1 is that in this comparative example, the solid electrolyte is polyethylene glycol.

All the other preparation methods and parameters are consistent with Example 1.

The gas-solid phase electrocatalytic electrodes provided in Examples 1-5 and Comparative Examples 1-2 were tested for catalytic oxidation of toluene at room temperature (25° C.), and the test process was as follows:

It is carried out in a gas-solid phase electrochemical reaction cell, and the reaction atmosphere circulates through the catalyst. The initial atmosphere composition is (40ppm toluene, 20% O ₂ , relative humidity 100%, total volume about 1.4L, N ₂ as balance gas, circulation flow rate 100mL/min). The anode is the electrode mentioned in the present invention, the cathode is a commercial Pt/C electrode, and the battery voltage is 3V. The results are shown in Table 1.

Table 1

It is carried out in a gas-solid phase electrochemical reaction cell, and the reaction atmosphere circulates through the catalyst. The initial atmosphere composition is (80ppm formaldehyde, 20% O ₂ , relative humidity 100%, total volume about 1.4L, N ₂ as balance gas, circulation flow rate 100mL/min). The anode is the electrode mentioned in the present invention, the cathode is a commercial Pt/C electrode, and the battery voltage is 3V. The results are shown in Table 2.

Table 2

Degradation time Formaldehyde removal rate (%) <![CDATA[CO₂Conversion Rate(%)]]> Example 1 1h 95 99 Example 2 1h 85 98 Example 3 1h 90 95 Example 4 1h 60 90 Example 5 1h 80 99 Comparative example 1 1h 48 80 Comparative example 2 1h 0 0

Based on the results of the data in Table 1 and Table 2, it can be seen that:

From the data results of Example 1 and Examples 4 and 5, it can be known that the mass concentration of the hydrophilic-based solid electrolyte solution is too small, which is not conducive to the activation of the active sites, and the mass concentration is too large, which will lead to an increase in resistance and a change in activity. Difference.

From the data results of Example 1 and Comparative Example 1, it can be known that rapid and thorough electrocatalytic oxidation cannot be achieved without the modification of the hydrophilic-based solid electrolyte.

From the results of the data of Example 1 and Comparative Example 2, it can be known that the solid electrolyte does not have conductivity, and the reaction cannot proceed.

In summary, the gas-solid-phase electrocatalytic electrode provided by the present invention is modified with a hydrophilic-based solid electrolyte, the electron transfer rate in the gas-solid phase reaction is accelerated, and the activation ability of water is significantly improved. All have shown good catalytic oxidation ability, and the preparation method is simple, the operation is simple and easy to realize automation, the mass concentration of the hydrophilic solid electrolyte is in the range of 5% to 35%, the gas-solid phase electrocatalytic electrode provided by the present invention is used When used to catalyze the oxidation of toluene, the removal rate of toluene can be over 70% and the conversion rate of _CO2 can be over 90% if it is degraded for 1 hour; when it is used to catalyze formaldehyde, the removal rate of formaldehyde can be over 85% after 1 hour of degradation, and the CO2 conversion rate can be over 85%. ₂ The conversion rate is above 95%.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention must rely on the above-mentioned detailed methods to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (11)

1. A gas-solid phase electrocatalytic electrode, characterized in that, the gas-solid phase electrocatalytic electrode comprises a conductive substrate, an anodic oxidation active layer and a hydrophilic solid electrolyte layer which are stacked in sequence; the anodic oxidation active layer comprises Oxidation of active oxides; the thickness of the hydrophilic-based solid electrolyte layer is 2-500 μm; the gas-solid phase electrocatalytic electrode is suitable for gas-solid phase reactions of double electrodes; The gas-solid phase electrocatalytic electrode is prepared by the following preparation method, and the preparation method includes the following steps: Prepare a catalyst precursor with an anodic oxidation active layer on the surface of a conductive substrate, and then coat a hydrophilic-based solid electrolyte solution on the surface of the anodic oxidation active layer to obtain the catalyst; the concentration of the hydrophilic-based solid electrolyte solution is 1 to 50 %. 2 . The gas-solid phase electrocatalytic electrode according to claim 1 , wherein the oxidation active oxide comprises SnO ₂ and/or PbO ₂ . 3 . The gas-solid phase electrocatalytic electrode according to claim 1 , wherein the loading capacity of the oxidation active oxide is 10-100 mg/cm ² . 4. The gas-solid phase electrocatalytic electrode according to claim 1, wherein the conductive substrate comprises any one or a combination of at least two of metal foam, metal mesh or carbon paper. 5. a preparation method of the gas-solid phase electrocatalytic electrode as described in any one of claim 1-4, is characterized in that, described preparation method comprises the following steps: Prepare a catalyst precursor with an anodic oxidation active layer on the surface of a conductive substrate, and then coat a hydrophilic-based solid electrolyte solution on the surface of the anodic oxidation active layer to obtain the catalyst; the concentration of the hydrophilic-based solid electrolyte solution is 1 to 50 %. 6. The method for preparing a gas-solid phase electrocatalytic electrode according to claim 5, wherein the concentration of the hydrophilic-based solid electrolyte solution is 5-35%. 7 . The method for preparing a gas-solid phase electrocatalytic electrode according to claim 5 , wherein the dosage of the hydrophilic-based solid electrolyte solution is 0.1-1 mL/cm ² . 8. the preparation method of gas-solid phase electrocatalytic electrode according to claim 5, is characterized in that, the preparation method of the catalyst precursor that the anodic oxidation active layer is set on the surface of described conductive substrate comprises: The oxidation active oxide is arranged on the surface of the conductive substrate by coating or electrodeposition. 9. the preparation method of gas-solid phase electrocatalytic electrode according to claim 5, is characterized in that, described preparation method comprises: The oxidation active oxide is arranged on the surface of the conductive substrate by coating or electrodeposition to obtain a catalyst precursor with an anodic oxidation active layer on the surface of the conductive substrate, and then a hydrophilic-based solid electrolyte solution with a mass concentration of 5-35% is added to The amount of 0.1-1mL/ ^cm2 is coated on the surface of the anodic oxidation active layer, and dried to obtain the catalyst. 10. A use of a gas-solid-phase electrocatalytic electrode, characterized in that the use comprises using the gas-solid-phase electrocatalytic electrode according to any one of claims 1-4 for electrochemical catalytic oxidation of indoor pollutants. 11. The use of the gas-solid phase electrocatalytic electrode according to claim 10, characterized in that the indoor pollutants include formaldehyde and/or benzene series.