Novel nanocrystalline zinc silver antimonate (ZnAg3SbO4): an efficient & ecofriendly visible light photocatalyst with enhanced hydrogen generation

Abstract

Herein, we report zinc silver antimonate (ZnAg3SbO4)/ZAS, a novel visible light active photocatalyst for hydrogen generation. The XRD pattern confirmed the formation of a highly crystalline single phase orthorhombic ZAS. The FESEM and TEM micrographs exhibited that the size of the nanoparticles are in the range ∼20–30 nm. An optical study showed a broad absorption edge from 400 to 1000 nm, with an estimated band gap of about ∼1.48 eV. Considering this ideal band gap, ZAS was used as a photocatalyst for the photodecomposition of H2S under visible light irradiation to produce hydrogen for the first time. We obtained the utmost hydrogen evolution i.e., ∼10 200 μmol h−1 g−1 for the naked ZAS (without a co-catalyst) catalyst under visible light, which is much higher than the earlier reported photocatalysts. Generally, in complex oxides of p-block metals, the bottom of the conduction band (CB) consists of the merely localized s and/or p orbitals which are largely dispersed. This large dispersion is responsible for a high electron mobility and extremely high photocatalytic activity. Therefore, a complex oxide (ZAS) of Ag, Zn and the p-block metal (Sb) is found to be a promising visible light active photocatalyst. This is the most stable, efficient and eco-friendly novel visible light active oxide photocatalyst for hydrogen production.