In situ preparation of N–ZnO/graphene nanocomposites: excellent candidate as a photocatalyst for enhanced solar hydrogen generation and high performance supercapacitor electrode

Abstract

We have demonstrated a facile in situ wet chemical method to synthesize nanostructured nitrogen doped ZnO/Graphene (N–ZnO/GR) nanocomposites for the first time. Nitrogen doped ZnO over graphene (N–ZnO/GR) was studied using various concentrations of graphene. During the synthesis of N–ZnO/GR nanocomposites, in situ formation of graphene via GO reduction and formation of 4–9 nm N–ZnO have been demonstrated. The composite N–ZnO/GR absorbs in the visible region and this property is used for the photocatalytic reaction to transform hazardous H₂S waste into eco-friendly hydrogen using solar light. The N–ZnO/GR nanocomposite with 0.3% graphene exhibits an enhanced photocatalytic stable hydrogen production rate i.e. ∼5072 μmol h⁻¹ under visible light irradiation. It is noteworthy that the N–ZnO/GR electrode exhibits a high specific capacitance of 555 F g⁻¹ and excellent cyclic performance with nearly 96.20% capacity retention after 2000 cycles at a current density of 10 A g⁻¹. These results indicate great potential applications of N–ZnO/GR in developing high hydrogen production and supercapacitors with high energy and power densities.