CN105067670A - Ordered Cu-doped nano-porous tin oxide sensing device - Google Patents

Abstract

The invention discloses an ordered Cu-doped nano-porous tin oxide sensing device. The sensing device is produced through the following steps: 1, producing an interdigital electrode-based graphene oxide film through adopting a spin coating method; 2, producing a device coated with a composite sensing film through a spin coating method, drying, and carrying out hot steam treatment; 3, removing a template from the device obtained in step 2; and 4, carrying out a reduction reaction on the device obtained in step 3 under an ultraviolet radiation condition to obtain the nano-porous tin oxide sensing device. The ordered Cu-doped nano-porous tin oxide sensing device has an excellent sensing performance, and the response time and the recovery time to low concentration H2S gas are shorter than 20s respectively.

Description

An ordered Cu-doped nanoporous tin oxide sensor device

technical field

The invention relates to a gas sensor, in particular to a film-type high-selectivity room-temperature H2S gas _- sensing device which uses copper oxide-doped ordered nanoporous tin oxide as a sensing material.

Background technique

With the rapid development of science and technology, modern industry has brought huge economic benefits and civilization progress to mankind, but it has also brought safety and environmental problems, especially in the production process of energy industries such as petroleum and coal. There are a lot of flammable, explosive and toxic substances . Faced with such serious safety and environmental problems, governments of various countries have increased investment in and research and development of sensor technology. The U.S. government has always attached great importance to the research and development support of sensor technology, and has introduced plans to develop new sensors for the detection of toxic and harmful gases out of the needs of energy security. In 2011, my country released the national medium and long-term plan, which clearly defined gas sensors for environmental monitoring equipment as the main development object. However, traditional gas sensors have disadvantages such as low detection sensitivity of low-concentration weak signals and poor selectivity. In order to achieve fast response, most of them use heating method to increase the working temperature of the sensor (working temperature 200-600°C). The introduction of the heating system not only increases energy consumption, but also easily detonates flammable gases, which brings huge safety hazards. For example, the optimal sensing temperature of the copper oxide-doped tin oxide-based hydrogen sulfide gas-sensitive material prepared in patent CN104502413 is 240°C.

Contents of the invention

The object of the present invention is to solve the defects in the prior art, and provide a sensing device capable of responding quickly to low concentration H ₂ S at room temperature.

In order to achieve the above object, the present invention provides a nanoporous tin oxide sensor device doped with ordered Cu, which is prepared by the following steps:

(1) Preparation of graphene oxide/interdigital electrode: prepare a polar graphene oxide solution with a concentration of 0.01-10 mg/ml (preferably 1 mg/ml), and adjust the pH value of the graphene oxide polar solution to 9- 10. Fabrication of graphene oxide films based on interdigitated electrodes by spin coating method;

(2) Preparation of devices coated with sensing materials: Take copper salt and tin salt with a mass ratio of 1:100-8:100 (preferably a molar ratio of 4:100), dissolve them in a polar solvent, and then add surface active agent, adjust the pH value to obtain a clear solution; use the spin coating method to coat the obtained clear solution on the device prepared in step (1) to obtain a device coated with a sensing material; dry the obtained device coated with a sensing material Afterwards, it is treated with hot steam for 1-4 days; the mass ratio of the surfactant to the tin salt is 0.4:100-6:100 (preferably the molar ratio is 0.48:100).

(3) removing the surfactant in the device obtained in step (2);

(4) Reduction: performing a reduction reaction on the device obtained in step (3) under the condition of ultraviolet irradiation to obtain the nanoporous tin oxide sensor device.

Wherein, the polar graphene oxide solution in the step (1) is a graphene oxide aqueous solution; the polar solvent in the step (2) is absolute ethanol.

The method of hot steam treatment in step (2) is as follows: put the dried device into an airtight container, adjust the relative humidity in the container to 70%-95%, and then put the container into a blast drying oven to adjust the temperature to 100~ 150°C.

The method for removing the templating agent in step (3) is as follows: place the device after the hot steam treatment in step (2) in a UV-O ₃ environment for 24-48h.

The copper salt adopts copper chloride, copper nitrate or copper sulfate, preferably copper chloride; the tin salt adopts anhydrous tin chloride, tin nitrate or tin sulfate, preferably anhydrous tin chloride; the interdigitated electrode adopts gold electrode or platinum electrode, Interdigitated gold electrodes are preferred.

The spin coating method in step (1) adopts a spin coating speed of 2000-4000rpm, and each spin coating time is 30-60s; the spin coating method step in step (2) is: in the homogenizer, by controlling the chamber of the homogenizer The humidity of the coating is 5%~50%, the speed of spin coating is 2000-4000rpm, the time of each spin coating is 30-60s, and the number of repetitions of coating is 1-10 times.

Compared with the prior art, the present invention has the following advantages:

1. The ordered nanoporous Cu-doped nano-tin oxide sensor device of the present invention has excellent sensing performance, and the response time and recovery time to low-concentration H ₂ S gas are both lower than 20s.

2. In the preparation process of the sensing device of the present invention, the preparation of the composite sensing material and the production of the sensor are carried out simultaneously, the experimental steps are simplified, the repeatability of the preparation of the sensing material is enhanced, the specific surface area of the sensing material is increased, and a high-quality p-n junction is formed, which is Carrier transport provides excellent channels, activates the surface adsorption capacity of grains, promotes surface reactivity, improves sensitivity and shortens response time, reduces the sensing temperature to room temperature, greatly enhances the working range of the gas sensor, and is conducive to Reduce energy consumption.

3. In the present invention, the ordered nanoporous tin oxide sensing material obtained by the thermal steaming method has an ordered structure and strong thermal stability; the UV _- O method is used to remove the surfactant, which avoids the destruction of the film structure by the traditional roasting method ;Using the UV reduction method to make full use of the reduction ability of the ultraviolet-excited tin oxide, the graphene oxide is effectively reduced. Compared with the traditional reduction method, this method is environmentally friendly, easy to operate, and low in cost.

Description of drawings

Fig. 1 is the SEM figure of the sensor device prepared in the embodiment of the present invention 1;

Fig. 2 is the one-dimensional SAXS scattering diagram of the sensing film after thermal steaming treatment and UV-O treatment in Example ₁ of the present invention;

Fig. 3 is the TEM picture of the surface sensing film of the sensor device prepared in Example 1 of the present invention;

FIG. 4 is a diagram of the sensing performance of the sensor device prepared in Example 1 of the present invention.

In Figure 1, 1-graphene, 2-interdigitated electrodes.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

Example 1

1. At room temperature, configure graphene oxide solution (solvent is deionized water) 1mg/ml, adjust the pH value to 9-10, start the homogenizer, take 100ul solution with a pipette, and control the speed of the homogenizer to 2000rpm , spin coating time is 30s.

2. Dry the device (interdigitated gold electrode) coated with graphene oxide at 60°C. Weigh 0.04g of copper chloride and 1g of anhydrous tin tetrachloride, dissolve them in absolute ethanol, add 0.4g of surfactant F127, then add 1ml of concentrated hydrochloric acid, mix well to obtain a clear solution. Start the homogenizer, fix the graphene oxide-coated device in the chamber of the homogenizer, control the humidity of the chamber to 10%, spin-coat at a speed of 4000rpm, spin-coat for 30s, and repeat the spin-coating once. After drying the above-mentioned newly prepared sensor material device, put the device into a closed container, adjust the relative humidity in the container to 70%, and then put the container into a blast drying oven to adjust the temperature to 100°C, and the reaction time is 4 days .

3. Under UV/O ₃ environment for 36h, and finally under UV light irradiation for 8h, an ordered nanoporous Cu-doped SnO ₂ sensor device based on graphene/gold electrodes was obtained.

Figure 1 is the SEM image of the ordered Cu-doped nanoporous _SnO2 sensor device prepared by the prepared graphene/gold electrode. It can be seen from the figure that the performance of the interdigitated electrode 2 has been greatly improved through the bridging of graphene 1. improvement.

Figure 2 is the SAXS image of the sensing film after step 2 treatment and after UV- _O3 treatment. It can be seen from the figure that both have good structural order.

Fig. 3 is the TEM photo of the prepared graphene/gold electrode to prepare ordered Cu-doped nanoporous _SnO sensor surface sensing film. It can be seen from the figure that the particle size of the nanoparticles is about 5nm, and the nanopores are along the 110 The crystal planes are arranged in a long-range order, and the average pore size is about 10nm.

Fig. 4 is the gas-sensing performance test chart of the ordered Cu-doped nanoporous _SnO2 sensor device prepared by the prepared graphene/gold electrode at room temperature. It can be seen from the figure that the sensitivity increases with the concentration of H2S from 20ppm _- 200ppm Change, and then reduced from 200ppm to 20ppm. The response time and recovery time of the sensor are both less than 20s.

Example 2

1. At room temperature, prepare a graphene oxide solution of 5 mg/ml, adjust the pH value to 9-10, start the homogenizer, take 100ul of the solution with a pipette, control the speed of the homogenizer to 2000rpm, and spin coating time to 45s.

2. Dry the device coated with graphene oxide at 60°C. Weigh 0.08g of copper nitrate and 1.5g of tin tetranitrate, dissolve them in absolute ethanol, add 0.36g of surfactant P123, then add 1ml of concentrated hydrochloric acid, mix well to obtain a clear solution. Start the homogenizer, fix the graphene oxide-coated device in the chamber of the homogenizer, control the humidity of the chamber to 30%, spin-coating speed to 4000rpm, spin-coating time to 45s, and repeat the spin-coating 5 times. After drying the above-mentioned newly prepared sensor material device, put the device into a closed container, adjust the relative humidity in the container to 80%, and then put the container into a blast drying oven to adjust the temperature to 120°C, and the reaction time is 2 days .

3. Under UV/O ₃ environment for 36 hours, and finally under UV light irradiation for 8 hours, an ordered Cu-doped nanoporous SnO ₂ sensor device based on graphene/gold electrodes was obtained.

The SAXS figure shows that the ordered sensing film after step 2 treatment, and the sensing film after UV- _O3 treatment have good structural order. The transmission electron micrographs of the sensing film on the surface of the prepared sensor device show that the particle size of the nanoparticles is about 5nm, the nanopores are arranged in a long-range order along the 110 crystal plane, and the average pore size is about 7nm. The gas-sensing performance test of the prepared sensor device was carried out at room temperature. The sensitivity changed from 20ppm to 200ppm with the concentration of H ₂ S, and then decreased from 200ppm to 20ppm. The response time and recovery time of the sensor were both less than 20s.

Example 3

1. At room temperature, prepare a graphene oxide solution of 10mg/ml, adjust the pH value to 9-10, start the homogenizer, take 100ul solution with a pipette, control the speed of the homogenizer to 2000rpm, and spin coating time to 60s.

2. Dry the device coated with graphene oxide at 60°C. Weigh 0.042g of copper sulfate and 1.3g of tin sulfate, dissolve them in absolute ethanol, add 0.36g of surfactant F127, then add 1ml of concentrated hydrochloric acid, mix well to obtain a clear solution. Start the homogenizer, fix the graphene oxide-coated device in the chamber of the homogenizer, control the humidity of the chamber to 50%, spin-coat at a speed of 4000rpm, spin-coat for 60s, and repeat the spin-coating 10 times. After drying the above-mentioned newly prepared sensing material device, put the device into an airtight container, adjust the relative humidity in the container to 95%, and then put the container into a blast drying oven to adjust the temperature to 150°C, and the reaction time is 1 day .

3. Under UV/O ₃ environment for 48h, and finally under UV light irradiation for 8h, an ordered Cu-doped nanoporous SnO ₂ sensor device based on graphene/gold electrodes was obtained.

The SAXS figure shows that the ordered sensing film after thermal evaporation treatment, and the sensing film after UV- _O3 treatment have good structural order. The transmission electron microscope photos of the sensing film layer on the surface of the prepared sensor device show that the particle size of the nanoparticles is about 5nm, the nanopores are arranged in a long-range order along the 110 crystal plane, and the average pore size is about 9nm. The gas-sensing performance test of the prepared sensor device was carried out at room temperature. The sensitivity changed from 20ppm to 200ppm with the concentration of H ₂ S, and then decreased from 200ppm to 20ppm. The response time and recovery time of the sensor were both less than 20s.

The preparation method of the present invention makes full use of the thermal steaming method, and realizes crystallization through subsequent processing at low temperature by preparing a sol solution, and realizes self-assembly during the crystallization process, and the order of the obtained film is improved. The crystal grains have a nanoscale size, the average particle size is about 5nm, and the order of the film is further improved after UV/ _O3 treatment; the preparation process of the present invention is simple, the requirements for equipment are not high, and it is easy to scale production; The ordered nanopore sensing material obtained by the invention has a compact structure, long-range order of the nanopores, and good sensing performance.

Claims (6)

1. the nano-pore tin oxide sensors part of an orderly Cu doping, it is characterized in that, described nano-pore tin oxide sensors part is prepared by following steps: (1) graphene oxide/interdigital electrode preparation: preparation concentration is the polar graphite oxide alkene solution of 0.01-10mg/ml, the pH value regulating graphene oxide polar solvent is 9-10, adopts spin-coating method preparation based on the graphene oxide film of interdigital electrode; (2) the device preparation of sensing material is coated with: get mantoquita and pink salt that mass ratio is 1:100-8:100, be dissolved in polar solvent, then add surfactant, adjust ph is to obtaining settled solution; Plated film on the device adopting spin-coating method to prepare in step (1) gained settled solution, must be coated with the device of sensing material; After device drying, through vapours process 1 ~ 4 day; The mass ratio of described surfactant and pink salt is 0.4:100-6:100; (3) surfactant in removal step (2) obtained device; (4) reduce: step (3) obtained device is carried out reduction reaction under ultraviolet irradiation condition, obtains described nano-pore tin oxide sensors part.

2. nano-pore tin oxide sensors part according to claim 1, is characterized in that, described step (1) Semi-polarity graphene oxide solution is graphene oxide water solution; Polar solvent in described step (2) adopts absolute ethyl alcohol.

3. nano-pore tin oxide sensors part according to claim 1 and 2, is characterized in that, the method removing template in described step (3) is as follows: process 24-48h under step (2) obtained device is placed in UV-O3 environment.

4. nano-pore tin oxide sensors part according to claim 1 and 2, it is characterized in that, vapours disposal route in described step (2) is as follows: dried device is put into closed container, regulate the relative humidity 70%-95% in container, then container is put into air dry oven and regulate temperature to be 100 ~ 150 DEG C.

5. nano-pore tin oxide sensors part according to claim 3, is characterized in that, described mantoquita adopts cupric chloride, copper nitrate or copper sulphate; Described pink salt adopts anhydrous stannic chloride, nitric acid tin or STANNOUS SULPHATE CRYSTALLINE; Described interdigital electrode adopts gold electrode or platinum electrode.

6. nano-pore tin oxide sensors part according to claim 3, is characterized in that, in described step (1), spin-coating method adopts spin speed to be 2000-4000rpm, each spin-coating time 30-60s; In described step (2), spin-coating method step is: in sol evenning machine, and be 5% ~ 50% by controlling the humidity of sol evenning machine cavity, the speed of spin coating is 2000-4000rpm, and each spin-coating time is 30-60s, and the multiplicity of plated film is 1-10 time.