Recent advances in ethanol gas sensors based on metal oxide semiconductor heterojunctions

Metal oxide semiconductor heterojunctions (MOSHs) can enhance the performance of ethanol gas sensors substantially. Ethanol gas sensors based on MOSHs are cost-effective and have excellent sensing response, good selectivity, fast response and recovery, long-term stability or repeatability, a low operating temperature, a facile fabrication process, and versatile applications. This paper reviews the recent advances in gas sensors that are based on MOSHs and the advantages of using them to detect ethanol gas. According to the literature, compared with ethanol gas sensors that use single-component sensing materials, the MOSHs exhibit superior performance due to the synergy between the different components, which can amplify the reception and transduction components of the sensor signals. To the best of our knowledge, heterojunctions can be grouped into four main categories as metal oxide/metal oxide, metal oxide/metal sulfide, metal oxide/noble metal, and metal oxide/other materials, including rare-earth metals, g-C3N4, and graphene, heterojunctions. The future trends and challenges that would be faced in the development of ethanol gas sensors based on MOSHs are discussed in detail. Finally, critical ideas and thinking regarding the future progress of MOSH-based gas sensors are presented.