MnO2 enhanced low temperature HCHO sensing performance of SnO2.

The exploration of gas sensing materials holds significant importance for practical applications. This work introduces a novel SnO 2 /MnO 2 nanocomposite designed to achieve formaldehyde monitoring at ppb level with a relative low temperature. The as prepared sensor demonstrates a response of 8.1–50 ppb formaldehyde at 100 °C. These remarkable formaldehyde sensing capabilities were explained by the heterojunction structure of the composite, and the low-temperature catalytic properties of MnO 2. Moreover, in-situ infrared reflectance spectroscopy was employed to investigate the underlying mechanism by monitoring the evolution of reaction intermediates, and the result suggested that the addition of MnO 2 can reduce the ineffective occupation of active sites and promote the generation of intermediate intermediates. • Heterojunction structure and catalytic effect is combined in one composite. • The response towards 50 ppb of formaldehyde is 8.1 at 100 °C. • The underlying mechanism has been investigated by in-situ DRIFTS. • The addition of catalyst can reduce the ineffective occupation of active sites. [ABSTRACT FROM AUTHOR]