Enhancing the surface Lewis basicity of phosphorene-hosted NiO nanosheets for sensitive and selective H₂S gas sensing

The selective detection of toxic gases is crucial for human health and air-quality monitoring, necessitating specialized customizations in the structure of sensing materials. In this study, we have profiled a black phosphorene (BP) hosted NiO nanosheet heterostructure for the sensitive and selective detection of trace H₂S gas. Both the theoretical and experimental investigations have indicated electron transfer from BP to NiO at the p-p interface, resulting in the electron-rich state of NiO and enhanced surface Lewis basicity. Such a Lewis basic surface would intrinsically empower acidic H₂S adsorption towards boosted H₂S detection. As a result, the optimized NiO/BP heterostructure showcases an improved H₂S sensing response, which is 1.9 and 3.5 times higher than those of NiO and BP at 150 °C to 5 ppm H₂S. It also illustrates stable sensing with fast kinetics, a low detectable limit (50 ppb), enhanced humid-resistivity, and H₂S selectivity. Computational calculations suggest that the NiO/BP structure can realize chemisorption with a negative free energy (−0.82 eV) toward sensitive/selective H₂S sensing. This research puts forward surface acidity/basicity as the criterion in rationalizing an efficient H₂S sensor through interface modification.