Compositing strategies to enhance the performance of chemiresistive CO2 gas sensors

Reliable and inexpensive CO2 gas sensors hold huge market potential as they are widely used in areas such as food package sectors, indoor air quality testing and real time monitoring of man-made CO2 emissions in order to curb the global warming effectively. Nanostructured materials have some distinctive advantages, such as small grain size, controlled growth of morphology and heterojunction effect provided by compositing techniques, making them potential candidates for chemiresistive CO2 gas sensors. This article presents an overview of the most recent developments in chemiresistive CO2 gas sensors based on nanostructured semiconducting materials with a particular emphasis on semiconducting composite structures, which include the mixing composite structure, second-phase decorated structure and bi-layer film structure. The correlations between compositing structures and their CO2 sensing properties are also highlighted, followed by the discussion of challenges and outlooks of chemiresistive CO2 gas sensors.