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 degrees 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.