A review: Strategies for enhancing the performance of SnO2-based formaldehyde gas sensors

Abstract

Formaldehyde (HCHO) is a harmful volatile organic compound (VOC) that presents significant environmental and health risks even at low concentrations, thus it needs to be accurately and efficiently detected. The development of high-performance HCHO sensors featuring higher sensitivity, selectivity, and rapid response is crucial for applications in environmental monitoring and public health protection. SnO₂-based gas sensors have drawn considerable attention due to their low cost, high sensitivity, and good stability. Nevertheless, challenges such as enhancing sensitivity, lowering operating temperatures, and ensuring long-term stability persist. In this article, the sensing mechanism of SnO₂ is initially introduced. Subsequently, the strategies for enhancing the gas sensitivity of SnO₂ HCHO sensors are reviewed, including morphological engineering, metal doping, forming heterojunctions with metal oxides, and composites with carbon-based materials or new materials. Finally, the challenges and future research directions are prospected.