Phosphorene-Derived Ni2P/NiO Lateral Heterostructure for Highly Sensitive and Selective H2S Gas Detection

Abstract

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 demonstrated 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 for the enhanced electrical conductivity over 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.