Hydrothermal synthesis of Co3O4-SnO2 p-n heterojunction with enhanced NO2 sensing performance

Preparation of Co 3 O 4 -SnO 2 heterostructures via hydrothermal method. • Peculiar morphology with abundant active sites and wide surface area. • Enhanced gas response (R g /R a ) of 92.8 with excellent sensitivity. • Excellent response is attributed to rapid charge transfer across p-n heterojunction. The recent development of p-n heterojunction sensors has attracted significant interest in gas sensing applications due to their excellent charge transfer, more active sites, and lower operating temperatures. In this research, Co 3 O 4 -SnO 2 heterostructured composite has been developed and investigated as a highly selective sensor for nitrogen dioxide (NO 2 ). The gas sensing results demonstrated a remarkable response of 92.8 to 100 ppm NO 2 at the optimal operating temperature of 200 °C. The sensor was tested over a wide temperature range (50–300 °C), demonstrating exceptional performance, remarkable repeatability, and consistent baseline recovery. The Co 3 O 4 -SnO 2 heterostructure has excellent long-term stability and consistently reliable detection across varying humidity conditions. The sensor's enhanced sensitivity to NO 2 was validated with selectivity tests for other interfering gases. An improved method revealing the NO 2 sensing approach is proposed, supported by density functional theory calculations to investigate the diffusion efficiency of investigated gases at Co 3 O 4 -SnO 2 heterostructures. The results indicated that Co 3 O 4 -SnO 2 heterostructures are an excellent option for practical NO 2 detection under different environmental conditions. Download: Download high-res image (400KB) Download: Download full-size image