A phosphorene-derived Ni₂P/NiO lateral heterostructure for highly sensitive and selective H₂S gas detection

The selective detection of toxic H₂S gas plays a critical role in safeguarding human health and monitoring air quality, imposing an essential requirement for specialized structural customizations of sensing materials. In this study, we have profiled and constructed a lateral Ni₂P/NiO hetero-nanosheet material via a facile in situ topological transformation from black phosphorene (BP) and exploited it for H₂S gas detection. The in situ growth method ensures an intimate interface with charge transfer between NiO and Ni₂P. For H₂S sensing, the optimized Ni₂P/NiO nanosheet (NS)-based sensor can operate at 150 °C and exhibits a high response value (resistance change ratio) of 24.8 to 5 ppm H₂S. It also demonstrates rapid sensing kinetics (<10 s), signal linearity (0.05-5 ppm), humidity resistivity, long-term stability, and enhanced selectivity towards H₂S. Density functional theory (DFT) calculations suggest that the Ni₂P/NiO heterostructure shows an increased density of states (DOS) near the Fermi level leading to enhanced electrical conductivity compared with individual components. It is also revealed that the heterostructure can significantly enhance the H₂S chemisorption capacity with a more negative Gibbs free energy (-0.70 eV). This study puts forward fundamental rationales for the design of advanced H₂S sensing materials through phosphide/oxide interface engineering.