Novel NiO nanoflakes in situ grown on graphene layers for the sensitive detection of low concentration H2S

• Synthesis of novel NiO nanoflakes in situ grown on Graphene layers via the simple method. • The unique microstructure endows the NiO sensing material with excellent H 2 S sensing performance. • The enhancement of H 2 S sensing performance by heterostructures was analyzed in detail. At present, the effective detection of H 2 S is of indispensable significance for safeguarding human health and maintaining production safety. In this study, a simple ammonia volatile liquid phase deposition method was adopted to in-situ construct cross-linked porous NiO nanoflakes composites on the surface of graphene (Gr) layers under mild conditions from room temperature to calcination. Through regulating the deposition reaction time, the proportion of NiO to Gr components in the composite material can be flexibly controlled. Among them, the NiO nanoflakes/Gr-8 material prepared by deposition for 8 h shows the optimal H 2 S gas sensitivity performance. At the optimal operating temperature of 92℃, the detection limit of H 2 S of this sensor is as low as 10 ppb, and its performance is significantly better than that of most sensing materials. Its outstanding performance stems from multi-dimensional structural optimization: NiO serves as the gas-sensitive active center to dominate the sensing response. The introduction of Gr increases the specific surface area of the material and significantly enhances its electrical conductivity. Particularly crucial is that the p-p heterostructure formed at the NiO/Gr interface effectively promotes the ionization of adsorbed oxygen ions. This study provides a new idea for the development of high-performance H 2 S gas sensors through a collaborative optimization strategy of “active components-conductive substrates-heterostructure interfaces”.