CN103412008A - Pd-doped SnO2 nanowire gas sensor for detecting H2 under low temperature, and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of semiconductor oxide gas sensors and in particular relates to a Pd-doped SnO2 nanowire gas sensor for detecting H2 under low temperature, and a preparation method of the Pd-doped SnO2 nanowire gas sensor. The sensor comprises a silicon oxide base plate covered by an interdigital platinum electrode, and an air-sensitive sensing layer; the air-sensitive sensing layer is formed by dispersing Pd-doped SnO2 nanowires, wherein the mass ratio of Pd to SnO2 nanowires is 1 to (15-468). The preparation method comprises the following steps: preparing SnO2 nanowires by adopting a thermal evaporation method; dispersing the SnO2 nanowires on the silicon oxide base plate covered by the interdigital platinum electrode, so as to form a SnO2 nanowire sensing layer; dispersing an ethanol solution of PdCl2 on the SnO2 nanowire sensing layer, and performing thermal treatment for 1h under the temperature being 300-400 DEG C so as to finally obtain the Pd-doped SnO2 nanowire gas sensor. The Pd-doped SnO2 nanowire gas sensor has an excellent air-sensitive characteristic under a low-temperature work condition, is good in reversibility and repeatability, and can effectively overcome the defect that the conventional gas sensor has a poor air-sensitive characteristic in a low-temperature area.

Description

For low temperature, detect H 2Pd doping SnO 2Nano wire gas sensor and preparation method

Technical field

The invention belongs to conductor oxidate gas sensor technical field, be specifically related to a kind of for low temperature detection H ₂Pd doping SnO ₂Nano wire gas sensor and preparation method.

Background technology

As a kind of clean and green energy resource, the products of combustion of hydrogen is water, and environment is not produced to any pollution, and will be widely used the every field in national life future.Yet, because hydrogen is a kind of colourless, odorless, nontoxic, inflammable and explosive gas, cause its more dangerous in transportation and storage process, as just to have explosion caused, fire if leak in air or people's Hypoxic is suffocated potential danger.Therefore, research is very necessary for detection of the high performance gas sensor with monitoring hydrogen.In the numerous hydrogen gas sensor of kind, the advantages such as that the gas sensor that the conductor oxidate of take is prepared from as gas sensitive has is highly sensitive, response is quick and cheap, its gas-sensitive reaction mechanism is mainly to belong to the surface resistance control type, be the adsorb oxygen ion of based semiconductor oxide surface and reacting of hydrogen, utilize the resistance variations of the conductor oxidate produced therefrom to measure the response condition to hydrogen.

For the conductor oxidate gas sensor, the initial ceramic mould of its research type experience, develop into thick-film type, film-type, until up-to-date micro Nano material type.The researchist is also by continuous effort, be devoted to improve the performance of conductor oxidate gas sensor, be sensitivity, selectivity and stability, the improvement method comprises and prepares porous film material, the compound conductor oxidate material of exploitation and carry out precious metal doping etc.Development along with nano science and nanometer technology, for the mini type gas sensor of development of new provides new research direction and platform, the researchist is upper the synthetic and application that more notice focuses on the one-dimentional structure nano material, as nanotube, nano wire, nanobelt, nanometer rods etc.With stupalith in the past, compare with membraneous material, the characteristics such as the single structure that monodimension nanometer material has, high-specific surface area and surfactivity, become it and have high sensitivity and high efficiency gas sensitive.

As N-shaped wide bandgap semiconductor oxide material, SnO ₂Hydrogen is had to good gas-sensitive property, is a kind of hydrogen gas sensor material that has research and application prospect.Although adopt SnO ₂Application of micron appears in the newspapers in the research work of hydrogen gas sensor, yet, great majority research is all just can obtain gas-sensitive property preferably under the working temperature more than 200 ℃, energy consumption height and the integrated complicacy of sensor have been caused detecting, such gas sensor is still lower to the sensitivity of low-concentration hydrogen, and further improving sensitivity needs urgently to be resolved hurrily.And current gas sensor technology is developing towards low temperature, low energy consumption, therefore, under the cryogenic conditions lower than 200 ℃, detecting H ₂The research and development of gas sensor be current hot technology.

Summary of the invention

For the problem that prior art exists, the invention provides a kind of for low temperature detection H ₂Pd doping SnO ₂Nano wire gas sensor and preparation method, purpose overcome traditional SnO ₂Nano material type gas sensor high energy consumption poor at the low-temperature region gas-sensitive property, that bring when high temperature detects and the integrated shortcomings such as complicacy, a kind of advantages such as highly sensitive, good reversibility, response/recovery are rapid that have are provided, are applicable to the gas sensor that low temperature detects hydrogen.

Realize that technical scheme of the present invention is:

A kind of Pd doping SnO that detects hydrogen for low temperature ₂The nano wire gas sensor, comprise a gentle quick inductive layer of monox substrate that is covered with interdigital platinum electrode, and described air-sensitive inductive layer is the SnO by the Pd doping ₂Nano wire disperses to form, wherein Pd and SnO ₂The mass ratio of nano wire is 1:(15～468).

The Pd doping SnO that detects hydrogen for low temperature of the present invention ₂The preparation method of nano wire gas sensor carries out according to following steps:

(1) prepare SnO ₂Nano wire:

1. quartz ampoule is placed in the open-type electric tube furnace, by diameter, be that 0.5～1mm, purity are that 99.99% metal Sn particle is placed on the monox substrate, the monox substrate is placed in to porcelain boat central authorities, porcelain boat is slowly sent into to the quartz ampoule central authorities heating zone in electric tube furnace;

2. with flange, fix quartz ampoule, then vacuumize, when vacuum tightness reaches 5Pa, in quartz ampoule, pass into argon gas with the flow velocity of 200ml/min, then repeat to vacuumize, pass into argon gas 1 time, regulating the argon gas flow velocity is 20～100ml/min, electric tube furnace to 800～1000 ℃ keep 0.5～1.5h of heating up subsequently, close electric tube furnace, treat that electric tube furnace naturally cools to room temperature, from quartz ampoule, taking out porcelain boat, the circumgranular milky sediment of metal Sn is the SnO of preparation ₂Nano wire;

(2) prepare the SnO of doping Pd ₂Nano wire:

1. by SnO ₂Nano wire is distributed in ethanolic solution, wherein SnO ₂The mass ratio of nano wire and ethanolic solution is 1:9, in ultrasonator, disperses subsequently 30min, is configured to SnO ₂The alcohol suspending liquid of nano wire, extract suspension with syringe, and it is distributed on the monox substrate that is covered with interdigital platinum electrode and forms SnO ₂The nano wire inductive layer;

2. by PdCl ₂Be dissolved in ethanolic solution, magnetic agitation 2h at room temperature, being mixed with concentration is 0.5 * 10 ³～3.125 * 10 ³The PdCl of mol/L ₂Ethanolic solution, extract PdCl with syringe ₂ Ethanolic solution 40 μ L, be distributed to SnO by it ₂On the nano wire inductive layer;

(3) prepare Pd doping SnO ₂The nano wire gas sensor:

By the above-mentioned SnO that is dispersed with ₂Nano wire and PdCl ₂The monox substrate in air at the temperature of 300～400 ℃ thermal treatment 1h, the final acquisition for low temperature detected H ₂Pd doping SnO ₂The nano wire gas sensor.

Compared with prior art, characteristics of the present invention and beneficial effect are:

The invention provides a kind of H with advantages such as low working temperature, high sensitivity, low-power consumption ₂Gas sensor and preparation method thereof, from the preparation method, at first the present invention utilizes thermal evaporation method to prepare to have high-specific surface area and surface-active SnO ₂Nano wire, then pass through to SnO ₂On nano wire, carry out the precious metals pd doping, preparation is simple, reproducible, and cost of manufacture is cheap, and output is high;

From on product, Pd doping SnO of the present invention ₂The gas sensor that the fabricate of nanowires forms, chemical effect and the electronic effect of adulterating and producing by precious metals pd, can when 100 ℃ of lower working temperatures, obtain the peak response to hydrogen, and under the working temperature of 50 ℃, has equally good gas-sensitive property, reversibility and favorable reproducibility, effectively having solved traditional hydrogen gas sensor in the poor deficiency of low-temperature region gas-sensitive property, is the hydrogen gas sensor with good development prospect.

The accompanying drawing explanation

Fig. 1 is that the present invention prepares SnO ₂The device schematic diagram of nano wire;

Wherein, 1: the open-type electric tube furnace; 2: quartz ampoule; 3: flange; 4: the metal Sn particle; 5: the monox substrate; 6: porcelain boat; 7: argon gas;

Fig. 2 is Pd doping SnO of the present invention ₂Nano wire gas sensor configuration schematic diagram;

Wherein: 8: interdigital platinum electrode; The 9:Pd SnO that adulterates ₂The air-sensitive inductive layer that nano wire forms;

Fig. 3 is SnO prepared by the present invention ₂The electron scanning micrograph of nano wire;

Fig. 4 is Pd doping SnO of the present invention ₂The transmission electron microscope photo of nano wire;

Fig. 5 is gas sensor of the present invention to the sensitivity of the 1000ppm hydrogen curve map with temperature change;

Fig. 6 is gas sensor of the present invention dynamic response curve figure to variable concentrations hydrogen in the time of 100 ℃;

Fig. 7 is gas sensor of the present invention dynamic response curve figure to variable concentrations hydrogen in the time of 50 ℃;

Fig. 8 is gas sensor of the present invention when 50 ℃ and 100 ℃ to the sensitivity curve figure of variable concentrations hydrogen.

Embodiment

Embodiment 1

A kind of Pd doping SnO that detects hydrogen for low temperature ₂The nano wire gas sensor, comprise a gentle quick inductive layer of monox substrate that is covered with interdigital platinum electrode, and described air-sensitive inductive layer is the SnO by the Pd doping ₂Nano wire disperses to form, wherein Pd and SnO ₂The mass ratio of nano wire is 1:40.

For low temperature, detect the Pd doping SnO of hydrogen ₂The preparation method of nano wire gas sensor carries out according to following steps:

(1) prepare SnO ₂Nano wire:

1. quartz ampoule is placed in the open-type electric tube furnace, by diameter, be that 0.5～1mm, purity are that 99.99% metal Sn particle is placed on the monox substrate, the monox substrate is placed in to porcelain boat central authorities, porcelain boat is slowly sent into to the quartz ampoule central authorities heating zone in electric tube furnace;

2. with flange, fix quartz ampoule, then vacuumize, when vacuum tightness reaches 5Pa, in quartz ampoule, pass into argon gas with the flow velocity of 200ml/min, then repeat to vacuumize, pass into argon gas 1 time, regulating the argon gas flow velocity is 50ml/min, and electric tube furnace to 900 ℃ keep 1h subsequently heats up, close electric tube furnace, treat that electric tube furnace naturally cools to room temperature, from quartz ampoule, taking out porcelain boat, the circumgranular milky sediment of metal Sn is the SnO of preparation ₂Nano wire, its electron scanning micrograph as shown in Figure 3, as can be seen from Figure 3, SnO ₂Nanowire surface is smooth, and diameter is 60～200nm, and length is tens microns;

(2) prepare the SnO of doping Pd ₂Nano wire:

1. by 0.5mg SnO ₂Nano wire is distributed in ethanolic solution, wherein SnO ₂The mass ratio of nano wire and ethanolic solution is 1:9, in ultrasonator, disperses subsequently 30min, is configured to SnO ₂The alcohol suspending liquid of nano wire, extract suspension with syringe, and it is distributed on the monox substrate that is covered with interdigital platinum electrode and forms SnO ₂The nano wire inductive layer;

2. get the PdCl of 5.21mg ₂Be dissolved in the ethanolic solution of 10mL, magnetic agitation 2h at room temperature, being mixed with concentration is 2.938 * 10 ³The PdCl of mol/L ₂Ethanolic solution, extract PdCl with syringe ₂ Ethanolic solution 40 μ L, be distributed to SnO by it ₂On the nano wire inductive layer;

(3) prepare Pd doping SnO ₂The nano wire gas sensor:

By the above-mentioned SnO that is dispersed with ₂Nano wire and PdCl ₂The monox substrate in air at the temperature of 350 ℃ thermal treatment 1h, the final acquisition for low temperature detected H ₂Pd doping SnO ₂Nano wire gas sensor, wherein Pd doping SnO ₂The transmission electron microscope photo of nano wire air-sensitive inductive layer as shown in Figure 4, as can be seen from Figure 4, is distributed in SnO ₂PdCl on nano wire ₂Under the heat-treat condition of 350 ℃, be oxidized to PdO particle (stain place in Fig. 4), its particle diameter is between 2～7nm.

In room temperature to 300 ℃ operating temperature range, the Pd SnO that adulterates ₂The nano wire gas sensor to the sensitivity of 1000ppm hydrogen with the curve map of temperature change as shown in Figure 5, as can be seen from Figure 5, in the low-temperature working district, particularly under the operational temperature conditions of 50～100 ℃, gas sensor of the present invention has good Sensitirity va1ue.

The Pd SnO that adulterates ₂The nano wire gas sensor is distinguished as shown in Figure 6 and Figure 7 at 100 ℃ of low temperature and 50 ℃ of figure of the dynamic response curve to variable concentrations hydrogen, as can be seen from the figure, gas sensor has response/release time comparatively fast to hydrogen when 100 ℃ of low temperature and 50 ℃, in 5 continuous reaction times, to the H of 100～1000ppm ₂Have good reversibility, sensitivity is along with the increase of density of hydrogen presents the trend increased progressively.

The Pd SnO that adulterates ₂The nano wire gas sensor when 50 ℃ and 100 ℃ to the sensitivity curve figure of variable concentrations hydrogen as shown in Figure 8, as can be seen from Figure 8 in density of hydrogen was 100～1000ppm scope, the sensitivity of this gas sensor was along with the increase of density of hydrogen presents the trend increased progressively.

Embodiment 2

A kind of Pd doping SnO that detects hydrogen for low temperature ₂The nano wire gas sensor, comprise a gentle quick inductive layer of monox substrate that is covered with interdigital platinum electrode, and described air-sensitive inductive layer is the SnO by the Pd doping ₂Nano wire disperses to form, wherein Pd and SnO ₂The mass ratio of nano wire is 1:15.

For low temperature, detect the Pd doping SnO of hydrogen ₂The preparation method of nano wire gas sensor carries out according to following steps:

(1) prepare SnO ₂Nano wire:

1. quartz ampoule is placed in the open-type electric tube furnace, by diameter, be that 0.5～1mm, purity are that 99.99% metal Sn particle is placed on the monox substrate, the monox substrate is placed in to porcelain boat central authorities, porcelain boat is slowly sent into to the quartz ampoule central authorities heating zone in electric tube furnace;

2. with flange, fix quartz ampoule, then vacuumize, when vacuum tightness reaches 5Pa, in quartz ampoule, pass into argon gas with the flow velocity of 200ml/min, then repeat to vacuumize, pass into argon gas 1 time, regulating the argon gas flow velocity is 20ml/min, and electric tube furnace to 800 ℃ keep 1.5h subsequently heats up, close electric tube furnace, treat that electric tube furnace naturally cools to room temperature, from quartz ampoule, taking out porcelain boat, the circumgranular milky sediment of metal Sn is the SnO of preparation ₂Nano wire;

(2) prepare the SnO of doping Pd ₂Nano wire:

1. by 0.2mg SnO ₂Nano wire is distributed in ethanolic solution, wherein SnO ₂The mass ratio of nano wire and ethanolic solution is 1:9, in ultrasonator, disperses subsequently 30min, is configured to SnO ₂The alcohol suspending liquid of nano wire, extract suspension with syringe, and it is distributed on the monox substrate that is covered with interdigital platinum electrode and forms SnO ₂The nano wire inductive layer;

2. get the PdCl of 5.54mg ₂Be dissolved in the ethanolic solution of 10mL, magnetic agitation 2h at room temperature, being mixed with concentration is 3.125 * 10 ³The PdCl of mol/L ₂Ethanolic solution, extract PdCl with syringe ₂Ethanolic solution 40 μ L, be distributed to SnO by it ₂On the nano wire inductive layer;

(3) prepare Pd doping SnO ₂The nano wire gas sensor:

By the above-mentioned SnO that is dispersed with ₂Nano wire and PdCl ₂The monox substrate in air at the temperature of 400 ℃ thermal treatment 1h, the final acquisition for low temperature detected H ₂Pd doping SnO ₂The nano wire gas sensor.

After testing, the sensor for preparing of the present embodiment under cryogenic conditions to H ₂Has good response effect.

Embodiment 3

A kind of Pd doping SnO that detects hydrogen for low temperature ₂The nano wire gas sensor, comprise a gentle quick inductive layer of monox substrate that is covered with interdigital platinum electrode, and described air-sensitive inductive layer is the SnO by the Pd doping ₂Nano wire disperses to form, wherein Pd and SnO ₂The mass ratio of nano wire is 1:468.

For low temperature, detect the Pd doping SnO of hydrogen ₂The preparation method of nano wire gas sensor carries out according to following steps:

(1) prepare SnO ₂Nano wire:

1. quartz ampoule is placed in the open-type electric tube furnace, by diameter, be that 0.5～1mm, purity are that 99.99% metal Sn particle is placed on the monox substrate, the monox substrate is placed in to porcelain boat central authorities, porcelain boat is slowly sent into to the quartz ampoule central authorities heating zone in electric tube furnace;

2. with flange, fix quartz ampoule, then vacuumize, when vacuum tightness reaches 5Pa, in quartz ampoule, pass into argon gas with the flow velocity of 200ml/min, then repeat to vacuumize, pass into argon gas 1 time, regulating the argon gas flow velocity is 100ml/min, and electric tube furnace to 1000 ℃ keep 0.5h subsequently heats up, close electric tube furnace, treat that electric tube furnace naturally cools to room temperature, from quartz ampoule, taking out porcelain boat, the circumgranular milky sediment of metal Sn is the SnO of preparation ₂Nano wire;

(2) prepare the SnO of doping Pd ₂Nano wire:

1. by 1mg SnO ₂Nano wire is distributed in ethanolic solution, wherein SnO ₂The mass ratio of nano wire and ethanolic solution is 1:9, in ultrasonator, disperses subsequently 30min, is configured to SnO ₂The alcohol suspending liquid of nano wire, extract suspension with syringe, and it is distributed on the monox substrate that is covered with interdigital platinum electrode and forms SnO ₂The nano wire inductive layer;

2. get the PdCl of 0.89mg ₂Be dissolved in the ethanolic solution of 10mL, magnetic agitation 2h at room temperature, being mixed with concentration is 0.5 * 10 ³The PdCl of mol/L ₂Ethanolic solution, extract PdCl with syringe ₂Ethanolic solution 40 μ L, be distributed to SnO by it ₂On the nano wire inductive layer;

(3) prepare Pd doping SnO ₂The nano wire gas sensor:

By the above-mentioned SnO that is dispersed with ₂Nano wire and PdCl ₂The monox substrate in air at the temperature of 300 ℃ thermal treatment 1h, the final acquisition for low temperature detected H ₂Pd doping SnO ₂The nano wire gas sensor.

After testing, the sensor for preparing of the present embodiment under cryogenic conditions to H ₂Has good response effect.

Claims (2)

1. one kind is detected H for low temperature ₂Pd doping SnO ₂The nano wire gas sensor, comprise a gentle quick inductive layer of monox substrate that is covered with interdigital platinum electrode, it is characterized in that described air-sensitive inductive layer is the SnO by the Pd doping ₂Nano wire disperses to form, wherein Pd and SnO ₂The mass ratio of nano wire is 1:(15～468).

2. prepare as claimed in claim 1 for low temperature detection H ₂Pd doping SnO ₂The method of nano wire gas sensor is characterized in that carrying out according to following steps:

(1) prepare SnO ₂Nano wire:

1. quartz ampoule is placed in the open-type electric tube furnace, by diameter, be that 0.5～1mm, purity are that 99.99% metal Sn particle is placed on the monox substrate, the monox substrate is placed in to porcelain boat central authorities, porcelain boat is slowly sent into to the quartz ampoule central authorities heating zone in electric tube furnace;

2. with flange, fix quartz ampoule, then vacuumize, when vacuum tightness reaches 5Pa, in quartz ampoule, pass into argon gas with the flow velocity of 200ml/min, then repeat to vacuumize, pass into argon gas 1 time, regulating the argon gas flow velocity is 20～100ml/min, electric tube furnace to 800～1000 ℃ keep 0.5～1.5h of heating up subsequently, close electric tube furnace, treat that electric tube furnace naturally cools to room temperature, from quartz ampoule, taking out porcelain boat, the circumgranular milky sediment of metal Sn is the SnO of preparation ₂Nano wire;

(2) prepare the SnO of doping Pd ₂Nano wire:

1. by SnO ₂Nano wire is distributed in ethanolic solution, wherein SnO ₂The mass ratio of nano wire and ethanolic solution is 1:9, in ultrasonator, disperses subsequently 30min, is configured to SnO ₂The alcohol suspending liquid of nano wire, extract suspension with syringe, and it is distributed on the monox substrate that is covered with interdigital platinum electrode and forms SnO ₂The nano wire inductive layer;

2. by PdCl ₂Be dissolved in the ethanolic solution of 10mL, magnetic agitation 2h at room temperature, being mixed with concentration is 0.5 * 10 ³～3.125 * 10 ³The PdCl of mol/L ₂Ethanolic solution, extract PdCl with syringe ₂Ethanolic solution 40 μ L, be distributed to SnO by it ₂On the nano wire inductive layer;

(3) prepare Pd doping SnO ₂The nano wire gas sensor:

By the above-mentioned SnO that is dispersed with ₂Nano wire and PdCl ₂The monox substrate in air at the temperature of 300～400 ℃ thermal treatment 1h, the final acquisition for low temperature detected H ₂Pd doping SnO ₂The nano wire gas sensor.

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