Facile in-situ synthesis of solid mediator based CdS-rGO-WO3 Z-scheme photocatalytic system for efficient photocatalytic hydrogen generation

Abstract

Reduced graphene oxide (rGO) solid state mediator based Z scheme photocatalyst CdS-rGO-WO3 heterojunction comprising of nano-rods of CdS and nanoplates of WO3 was fabricated in-situ by a facile hydrothermal process, characterized and tested for solar hydrogen generation. The systematically designed heterojunction created separated oxidative and reductive sites for photo generated electron hole pairs with enhanced redox ability, improving the charge separation and photo-stability, mitigating the problem of photo-corrosion of CdS. This was evident from an enhanced photocatalytic activity of 11.69 mmolg−1h−1 which was almost 2.3 times than pristine CdS (4.9 mmolg−1h−1), in presence of simulated solar light. Due to the high electron mobility property of graphene sheet, rapid transport of electrons was possible at the interface between CdS and WO3. The charge transfer via Z scheme mechanistic pathway was verified by X-ray Photoelectron Spectroscopy (XPS), Photoluminescence (PL) and photocurrent measurement studies. This research study will provide a newer insight in engineering nano-hetero-structures for enhanced photocatalytic hydrogen evolution, in an attempt to make the process commercially viable.