A semiconductor resistive gas sensor and its preparation method

Abstract

The invention discloses a semiconductor resistance gas sensor and a preparation method thereof. The gas sensor includes an insulating substrate, a signal electrode and a gas-sensing layer; the gas-sensing layer is composed of semiconductor nanocrystalline composite material and graphene. The colloidal method is used to synthesize the semiconductor nanocrystal solution, which can directly form a film at room temperature without high temperature treatment, consumes less energy, and does not cause the agglomeration of nanoparticles, and can maximize the advantages of large specific surface area of ​​nanoparticles. It is conducive to gas adsorption, improves the sensitivity of the sensor, and enables the sensor to detect low-concentration target gas at a lower working temperature or even at room temperature. The preparation method is simple, and it is easy to realize large-scale batch production.

Description

technical field [0001] The invention belongs to the technical field of gas sensitive materials and components, and more specifically relates to a semiconductor resistive gas sensor and a preparation method thereof. Background technique [0002] The inherent sensitivity mechanism of the semiconductor resistive gas sensor determines that it is sensitive to a variety of gases and lacks selectivity, making it difficult to accurately identify the target gas, and it has certain requirements for the operating temperature, and the operating temperature affects the sensitivity of the gas-sensitive material to The reactivity of the gas, the state of chemically adsorbed oxygen on the surface, and the electron exchange process determine the sensitivity. With hydrogen sulfide (H 2 S) gas as an example, tin oxide (SnO 2 ) The optimal working temperature of the gas sensor is 150°C. Although the gas sensing characteristics can be improved to a certain extent by doping noble metal catalyst...

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Problems solved by technology

The study found that when SnO 2 When the ratio of ZnO to ZnO is 1:1, the maximum sensitivity of the material to methanol is about 9, but the preparation method of the device is too cumbersome, time-consuming and laborious, which is not conducive to the repetitive production of the device and industrial production application

Gupta et al. used laser deposition to prepare SnO 2 / CuO nanocomposite and studied its effect on H 2 The sensitivity of S gas is higher than that of pure-phase materials, but this preparation method requires high process precision and high sensor operating temperature, which is not conducive to composite materials taking advantage of nanomaterials in real devices.

Xue et al. successfully prepared the H 2 S gas heterojunction SnO 2 / CuO sensor, however, a high degree of sintering at 800 °C is required during the preparation process, resulting in additional energy loss

In 2014, Liu et al. synthesized nanoflower-like ZnO by a chemical water bath method, and obtained a NiO / ZnO heterostructure material with NiO nanoparticles on the surface after stirring and calcining the solution. The excessively high calcining temperature also has the problem of energy loss.

At the same time, in the field of sensors using nano-composite materials as gas-sensitive materials, there is also the problem of excessive initial resistance of the device, which puts forward higher requirements for the circuit structure and increases the difficulty of detection in actual use.

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