阅读说明：本技术 一种乙醇传感器、合成方法 (Ethanol sensor and synthesis method ) 是由 王莹麟 李旭 程鹏飞 刘彦明 党凡 张耀琼 于 2020-04-20 设计创作，主要内容包括：本发明属于半导体氧化物气体传感器技术领域,公开了一种乙醇传感器、合成方法,通过高温退火去除C-球模板,合成出Au@SnO<Sub>2</Sub>空心微球,然后通过调节氯金酸的量将Au包裹在C-球模板中。Au包裹的SnO<Sub>2</Sub>传感器的灵敏度是基于纯SnO<Sub>2</Sub>的传感器的三倍,并且最佳工作温度降至240℃。此外,它还具有出色的响应恢复时间。现象表明,Au增加了敏感材料表面化学吸附氧的容量(催化特性)。Au@SnO<Sub>2</Sub>空心微球的分层结构还提供了更多的活性部位来感知乙醇(结构特征)。所有结果表明,Au@SnO<Sub>2</Sub>分级中空微球在乙醇检测中具有广泛的潜在应用前景。(The invention belongs to the technical field of semiconductor oxide gas sensors, and discloses an ethanol sensor and a synthesis method 2 Hollow microspheres, and then wrapping Au in the C-sphere template by adjusting the amount of chloroauric acid. Au-coated SnO 2 The sensitivity of the sensor is based on pure SnO 2 Three times that of the sensor and the optimum operating temperature drops to 240 ℃. In addition, it has excellent response recovery time. The phenomenon shows that Au increases the capacity of the sensitive material surface to chemically adsorb oxygen (catalytic properties). Au @ SnO 2 The layered structure of the hollow microspheres also provides more active sites to perceive ethanol (structural features). All results show that Au @ SnO 2 The hierarchical hollow microspheres have wide potential application prospect in ethanol detection.)

1. A method for synthesizing an ethanol sensor is characterized by comprising the following steps:

step one, synthesizing a C ball by a hydrothermal method, collecting an absolute ethyl alcohol cleaning product, drying and collecting the absolute ethyl alcohol cleaning product, and calcining in a nitrogen atmosphere;

secondly, ultrasonically dispersing prepared different C ball templates in deionized water, ultrasonically adding stannous chloride and oxalic acid into the solution, and stirring until the stannous chloride and the oxalic acid are dissolved; and (4) performing a hydrothermal link, washing the precipitate by using deionized water and ethanol after the reaction is finished, drying and calcining.

2. The method for synthesizing the ethanol sensor according to claim 1, wherein the hydrothermal conditions for hydrothermal synthesis of the C ball in the first step are as follows: at 180 ℃ for 12 hours; the hydrothermal time of the Au @ C ball template is shortened to 180 ℃ for 10 hours;

in the first step, the product is washed by absolute ethyl alcohol, dried and collected, and then calcined for 2 hours at 450 ℃ in the nitrogen atmosphere.

3. The method of synthesizing an ethanol sensor according to claim 1, wherein the first step further comprises: synthesizing an Au @ C template, dissolving 3g of glucose in 50mL of deionized water, stirring until the glucose is dissolved, and adding 0.12mL,0.24mL and 0.5mL of chloroauric acid solution into the solution; placing the above solution into a 50mL polytetrafluoroethylene liner; placing into a stainless steel reactor, heating at 180 deg.C for 10 hr to obtain black sand-like product, washing with deionized water and ethanol to remove impurities, drying at 80 deg.C overnight, and adding N₂Annealing was carried out in an atmosphere at a temperature of 450 ℃ for 2 hours.

4. The method for synthesizing the ethanol sensor according to claim 1, wherein in the second step, the prepared different C sphere templates are ultrasonically dispersed in 50mL of deionized water for 30 minutes; adding 3mol of stannous chloride and 0.3mol of oxalic acid into the solution, and fully stirring until the stannous chloride and the oxalic acid are dissolved;

and in the second step, performing a hydrothermal link, performing hydrothermal treatment at 180 ℃ for 6 hours, washing the precipitate by using deionized water and ethanol after the reaction is finished, and calcining the precipitate for 2 hours at 500 ℃ after the precipitate is dried.

5. The method of synthesizing an ethanol sensor according to claim 1, wherein the second step further comprises: synthesis of Au @ SnO₂Grading microspheres, namely weighing 3mol of stannous chloride and dissolving the stannous chloride in 50mL of deionized water; stirring for 30 minutes until the solution is transparent, dissolving the prepared carbon spheres in a stannous chloride solution, uniformly dispersing the carbon spheres in the solution through continuous stirring and ultrasonic treatment, and after stirring for 30 minutes, adding 0.3mol of oxalic acid into the solution until the oxalic acid is completely dissolved; carrying out hydrothermal treatment for 6 hours at 180 ℃, thoroughly washing the product by using deionized water and ethanol, and drying for 8 hours at 60 ℃; annealing the dried product in an oxygen atmosphere at a temperature of 500 ℃ for 2 hours to completely oxidize tin ions to SnO₂And removing the carbon sphere template.

6. The method of synthesizing an ethanol sensor according to claim 1, wherein the second step is followed by:

step one, weighing prepared SnO₂0.3g of powder is dispersed in deionized water and stirred into paste, and the paste is coated on a ceramic tube with a gold electrode by using a brush; the heating resistance wire penetrates through the ceramic tube and is welded on the hexagonal base for testing;

and step two, measuring the resistance of the sensor by using a digital multimeter, and controlling the working temperature by using the current passing through a heating resistance wire of an ammeter.

7. An ethanol sensor synthesized by the method for synthesizing an ethanol sensor according to any one of claims 1 to 6.

Technical Field

The invention belongs to the technical field of semiconductor oxide gas sensors, and particularly relates to an ethanol sensor and a synthesis method.

Background

Currently, SnO₂As the most widely used semiconductor metal oxide materials, the material is widely applied to a plurality of fields such as solar cells, lithium batteries, electro-optic chemical catalysis, capacitors and the like. While SnO₂Applied to the field of gas sensors and generally used for detecting ethanol, acetone, formaldehyde and H₂And (4) S gas. Conventional SnO₂The gas sensor has poor selectivity, high working temperature and poor stability. Therefore, regulated SnO is now being used gradually₂The micro-morphology, the construction of p-n junctions, the doping of metal ions and other technologies improve the problems. In the prior art, a hydrothermal synthesis method is adopted to prepare SnO₂In CoO₂After compounding, the compound proves that the compound plays a role in promoting the sensing performance of the ethanol. At 340 ℃ CoO₂-SnO₂The sensor showed excellent selectivity characteristics for ethanol. But the operating temperature is high, which increases a lot of unnecessary power consumption. The synthesis of C sphere template is mature at present, and the synthesis research of the carbon sphere coated metal ion template is less. Studies on the complexing of different amounts of metal ions with C spheres have also been rarely reported.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) the sensitivity of the prior art for detecting organic gases is not high.

(2) The working temperature of the prior art semiconductor metal oxide gas sensor is higher.

(3) Prior art n-type semiconductor SnO as typical₂The selectivity towards different gases is poor, in particular to distinguish between ethanol and acetone.

The difficulty in solving the above problems and defects is: studies have shown that the influence on the particle size of carbon spheres is generally due to factors such as hydrothermal time and temperature. In the synthesis process of the carbon spheres, a certain amount of acid is added to accelerate the Ostwald ripening reaction.

The significance of solving the problems and the defects is as follows: the invention can realize the particle size of Au @ C by selecting experimental conditionsKeeping the same with the diameter of the pure carbon pellet. Oxalic acid as structure directing agent to make SnO₂And secondary growth is carried out under the support of the hard template, so that the utilization rate of the sensitive material is improved, and the gas adsorption and diffusion rates are increased. SnO for coating gold particles₂As for the microspheres, Au is used as a catalyst for the reaction, so that the energy required by the reaction can be reduced, the working temperature of the sensor can be reduced, and the power consumption can be reduced. In addition, Au @ SnO₂The sensor shows good selection characteristics for different organic volatile gases.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an ethanol sensor, a synthesis method, a solar cell, a lithium battery and a capacitor.

The invention is realized in such a way that the synthesis method of the ethanol sensor comprises the following steps:

step one, synthesizing a C ball by a hydrothermal method, collecting an absolute ethyl alcohol cleaning product, drying and collecting the absolute ethyl alcohol cleaning product, and calcining in a nitrogen atmosphere;

secondly, ultrasonically dispersing prepared different C ball templates in deionized water, ultrasonically adding stannous chloride and oxalic acid into the solution, and stirring until the stannous chloride and the oxalic acid are dissolved; and (4) performing a hydrothermal link, washing the precipitate by using deionized water and ethanol after the reaction is finished, drying and calcining.

Further, hydrothermal conditions for synthesizing the C balls by the hydrothermal method in the first step are as follows: at 180 ℃ for 12 hours; c balls are synthesized at 180 ℃ for 12 hours so that glucose can be successfully carbonized into the C balls, excessive reaction cannot occur, and the C balls with the uniform particle size and the particle size of about 500nm are obtained under proper conditions. The hydrothermal time of the Au @ C ball template is shortened to 180 ℃ for 10 hours; the reason for shortening the hydrothermal time is that chloroauric acid is added as a gold source in the process of synthesizing Au @ C, but the solution is acidic, so that the process of glucose carbonization is accelerated. If the glucose is carbonized too sufficiently, the particle size becomes uneven and the particle size becomes large rapidly. Therefore, the particle size of the Au @ C sphere template after 10 hours is selected to achieve the effect of almost conforming to the particle size of the C spheres.

The product is washed by absolute ethyl alcohol in the first step, dried and collected, and then calcined in an atmosphere of nitrogen at 450 ℃ for 2 hours. Nitrogen was chosen as the protective gas because the C spheres were prevented from contacting oxygen during the high temperature calcination, and were calcined at 450 ℃ to ensure the Au particles were shaped.

Further, the first step further includes: synthesizing an Au @ C template, dissolving 3g of glucose in 50mL of deionized water, stirring until the glucose is dissolved, and adding 0.12mL,0.24mL and 0.5mL of chloroauric acid solution into the solution; placing the above solution into a 50mL polytetrafluoroethylene liner; placing into a stainless steel reactor, heating at 180 deg.C for 10 hr to obtain black sand-like product, washing with deionized water and ethanol to remove impurities, drying at 80 deg.C overnight, and adding N₂Annealing was carried out in an atmosphere at a temperature of 450 ℃ for 2 hours.

Further, in the second step, the prepared different C sphere templates are ultrasonically dispersed in 50mL of deionized water for 30 minutes; adding 3mol of stannous chloride and 0.3mol of oxalic acid into the solution, and fully stirring until the stannous chloride and the oxalic acid are dissolved;

and in the second step, performing a hydrothermal link, performing hydrothermal treatment at 180 ℃ for 6 hours, washing the precipitate by using deionized water and ethanol after the reaction is finished, and calcining the precipitate for 2 hours at 500 ℃ after the precipitate is dried.

Further, the second step further includes: synthesis of Au @ SnO₂Grading microspheres, namely weighing 3mol of stannous chloride and dissolving the stannous chloride in 50mL of deionized water; stirring for 30 minutes until the solution is transparent, dissolving the prepared carbon spheres in a stannous chloride solution, uniformly dispersing the carbon spheres in the solution through continuous stirring and ultrasonic treatment, and after stirring for 30 minutes, adding 0.3mol of oxalic acid into the solution until the oxalic acid is completely dissolved; carrying out hydrothermal treatment for 6 hours at 180 ℃, thoroughly washing the product by using deionized water and ethanol, and drying for 8 hours at 60 ℃; annealing the dried product in an oxygen atmosphere at a temperature of 500 ℃ for 2 hours to completely oxidize tin ions to SnO₂And removing the carbon sphere template.

Further, the second step is followed by:

step (ii) ofFirstly, weighing prepared SnO₂0.3g of powder is dispersed in deionized water and stirred into paste. Coating the ceramic tube with the gold electrode by using a brush; the heating resistance wire penetrates through the ceramic tube and is welded on the hexagonal base for testing;

and step two, measuring the resistance of the sensor by using a digital multimeter, and controlling the working temperature by using the current passing through a heating resistance wire of an ammeter.

Another object of the present invention is to provide an ethanol sensor synthesized by the method for synthesizing an ethanol sensor.

By combining all the technical schemes, the invention has the advantages and positive effects that: the invention reduces the working temperature of the sensor and realizes the reduction of power consumption; the selection characteristic and the sensitivity of the sensor are improved.

The SnO is synthesized by combining oxalic acid serving as a structure directing agent with carbon spheres of a hard template₂The hollow microspheres are graded, so that the rapid and high-sensitivity response to ethanol is realized; the content of gold particles is regulated and controlled by controlling the amount of chloroauric acid in the synthesized carbon spheres, and the particle size of the Au @ C spheres is consistent with that of the carbon spheres; au @ SnO obtained by high-temperature calcination₂The graded hollow microspheres are realized as SnO₂The detection sensitivity is more than 3 times, and the working temperature (SnO) is reduced compared with the detection sensitivity₂:260℃，[email protected]₂:240℃)

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.

FIG. 1 is a flow chart of a method for synthesizing an ethanol sensor according to an embodiment of the present invention.

FIG. 2 is a diagram of the synthesis of an experiment provided by an embodiment of the present invention.

FIG. 3 is a schematic diagram of a scanning electron microscope of a sample provided by an embodiment of the invention;

in the figure: (a) c, a ball template; (b) an Au @ C ball template; (c) SnO₂Microspheres; (d) au @ SnO₂And (3) microspheres.

FIG. 4 shows SnO (a) provided by an embodiment of the present invention₂Transmission electron microscopy of microspheres; (b) au @ SnO₂A projection electron microscope image of (a); (c) au @ SnO₂A pattern of lattice spacings of; (d) - (f) respectively Au @ SnO₂The element distribution of the sample is Sn, O and Au respectively.

FIG. 5 is a graph of sensitivity of all devices as a function of operating temperature, as provided by an embodiment of the present invention (a), with an interpolated plot reflecting the resistance of all devices in air as a function of operating temperature; (b) dynamic sensitivity profiles of all devices for different concentrations of ethanol gas; (c) linear fit plots of all devices for different concentrations of ethanol gas; (d) linear fit plots of the S1 and S3 samples.

FIG. 6 is a bar graph of the selectivity for different organic gases for all samples at the optimum operating temperature provided by the present example; the S3 sample at its optimum operating temperature for 100ppm ethanol gas: (b) long term stability curve for 30 days; (c) resistance plots were run five times.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In order to solve the problems in the prior art, the invention provides an ethanol sensor and a synthesis method, and the invention is described in detail below with reference to the accompanying drawings.

The ethanol sensor provided by the invention is a microsphere with a hierarchical structure synthesized by mutually assisting the structure directing agent and the hard template.

As shown in fig. 1, the synthesis method of the ethanol sensor provided by the invention comprises the following steps:

s101: synthesizing the C ball by a hydrothermal method, wherein the specific hydrothermal conditions are as follows: at 180 ℃ for 12 hours. After the experiment is finished, the product is washed and collected by using absolute ethyl alcohol. And the hydrothermal time of the Au @ C sphere template is shortened to 180 ℃ for 10 hours. After the product was dried and collected by washing with absolute ethanol, it was calcined at 450 ℃ for 2 hours in an atmosphere of nitrogen.

S102: and ultrasonically dispersing the prepared different C sphere templates in 50mL of deionized water for 30 minutes, and then adding 3mol of stannous chloride and 0.3mol of oxalic acid into the solution to be fully stirred until the stannous chloride and the oxalic acid are dissolved. Then carrying out a hydrothermal link, and carrying out hydrothermal treatment at 180 ℃ for 6 h. After the reaction is finished, washing the precipitate by using deionized water and ethanol, and calcining for 2 hours at 500 ℃ after drying.

S103: weighing the prepared SnO₂0.3g of powder is dispersed in deionized water and stirred into paste. The coating was applied to a ceramic tube with a gold electrode using a brush. And the heating resistance wire penetrates through the ceramic tube and is welded on the hexagonal base for testing.

S104: the resistance of the sensor was measured using a digital multimeter, while the operating temperature was controlled using the current passed through the heating resistance wire of an ammeter.

As shown in fig. 2, the synthesis method of the ethanol sensor provided by the present invention specifically includes the following steps:

the first step is as follows: the Au @ C template was synthesized by dissolving 3g of glucose in 50mL of deionized water and stirring well until dissolved, and adding varying amounts (0.12mL,0.24mL,0.5mL) of chloroauric acid solution to the above solution. The above solution was then placed into a 50mL teflon liner, which was then placed into a stainless steel reactor and heated at 180 ℃ for an additional 10 h. After the reaction time has ended, a black sandy product will be obtained. The product was washed alternately with deionized water and ethanol to wash out impurities. The final product was dried at 80 ℃ overnight, all products being in N₂Annealing was carried out in an atmosphere at a temperature of 450 ℃ for 2 hours.

The second step is that: synthesis of Au @ SnO₂Grading microspheres, weighing 3mol of stannous chloride and dissolving in 50mL of deionized water. Stir for 30 minutes until the solution is clear. The carbon spheres prepared in advance are dissolved in a stannous chloride solution, and are uniformly dispersed in the solution through continuous stirring and ultrasonic treatment. After stirring for 30 minutes, 0.3mol of oxalic acid was added to the above solution until complete dissolution. Then carrying out reaction at 180 DEG CHydrothermal treatment was carried out for 6 hours. Finally, the product was washed thoroughly with deionized water and ethanol and dried at 60 ℃ for 8 hours. Annealing the dried product in an oxygen atmosphere at a temperature of 500 ℃ for 2 hours to completely oxidize tin ions to SnO₂And removing the carbon sphere template.

The technical solution of the present invention is further described below with reference to the accompanying drawings.

Due to the adsorption of oxygen on the surface of the sensitive material, electron transfer occurs at the surface and a depletion layer is formed at the surface. The use of sensitive materials is improved when the grain size is about twice the debye length, and thus higher responsivity can be achieved. When SnO is used₂The debye length was 6nm when ethanol was detected. In our work, the secondary particle size is about 10 nm. Thus, the particles are almost completely consumed, thereby increasing SnO₂Utilization ratio, thereby improving performance. In addition, oxalic acid as a structure directing agent can regulate SnO₂Secondary growth of particles, wherein secondary particles of 3D spheres accumulate with the aid of C sphere templates. After the carbon template is removed, the formed hollow microsphere structure with the thin shell layer improves the gas permeability and provides more active sites, so that the gas and the sensitive material can react to the maximum extent. Compared with S1 sensor, Au @ SnO₂The sensing performance of the graded hollow microsphere is obviously improved, which is also attributed to the excellent catalytic action of the Au nano-particles. When the sensor is exposed to the detection gas, the catalytic action of Au promotes the decomposition of ethanol into more active radical groups and lowers the activation energy of the sensitive material. According to the literature, SnO₂And the work functions of Au were 4.83eV and 5.1eV, respectively. Electrons from SnO due to differences between work functions₂Transferred to Au, a schottky barrier is formed when the equilibrium point is reached. Electrons must overcome this potential energy barrier to pass through Au and SnO₂The interface of the contact. Due to the presence of such a high potential barrier, the number of electrons in the depletion layer gradually decreases, which narrows the electron transport channel and forms a higher resistance, so that a greater response can be obtained in detecting the reducing gas.

The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.