金属氧化物异质结气体传感器气敏增强机理

Enhanced Gas Sensing Mechanisms of Metal Oxide Heterojunction Gas Sensors

金属氧化物异质结由于费米能级效应、不同组分之间的协同作用,常被用来提高电阻型金属氧化物半导体气体传感器的气敏特性。本文简述了近年来国内外金属氧化物异质结材料的类别,主要分为混合氧化物结构、层状结构、第二相粒子修饰结构、一维纳米结构和核-壳结构;重点综述了金属氧化物异质结的气敏增强机理,包括异质结效应、协同效应、催化溢流效应、响应反型、载流子分离及微结构调控六大机理;分析了当前异质结气体传感器面临的瓶颈。最后对纳米异质结气体传感器的发展进行了展望,今后金属氧化物异质结气体传感器可以从明确异质结界面机理展开,这将为自下而上地设计出符合实际需要的气体传感器提供一定参考。

The metal oxide heterojunction has often been used to improve the gas sensing properties of resistive metal oxide semiconductor gas sensors. Metal oxide heterojunctions have been demonstrated to have many unique properties such as Fermi-level mediated charge transfer effects as well as synergistic behavior of different components. In this short review, we summarize the fundamental types of metal oxide heterojunction materials reported in domestic and foreign research in recent years. Metal oxide heterojunctions are mainly divided into five categories of mixed composite structures, multi-layer films, structure modified with a second phase, 1D nanostructure and core-shell structure. We review the enhanced gas sensing mechanisms of metal oxide heterojunctions. These mechanisms are discussed in detail, including the role of the heterojunction,synergistic effects, the spill-over effect, response-type inversion, separation of charge carriers, and microstructure manipulation. We also analyze the remaining challenges of metal oxide heterojunction gas sensors. Finally, we provide an outlook for future development of metal oxide heterojunction gas sensors. The future research directions of metal oxide heterojunction gas sensors can be developed from the definition of heterojunction interface mechanisms. It is hoped that determining the heterojunction interface mechanisms will provide some reference for the design of needed gas sensors in a bottom-up route.