Interface and Structural Engineering of Cr Doped Zinc Oxide/Graphene Photoanode with Enhanced Photoelectrochemical Water Splitting

Abstract

The low-cost hydrogen (H2) generation from solar energy is one of the attractive and promising methods for clean and sustainable energy. It is challenging to boost global, renewable H2 energy mission. Until now, no catalytic system has been realized with viable efficiency and stability with reasonable manufacturing cost. Herein, we demonstrate a facile synthesis of chromium doped zinc oxide/graphene (Cr-doped ZnO@Graphene) as multicomponent photoanode using simple, inexpensive hydrothermal method. We investigated that graphene layer beneath ZnO can act in a different way, while salient features of controllable graphene concentration and appropriate Cr doping clearly displayed profound influence on photoelectrochemical water splitting reaction which is due to promoted electron transfer at interface. The detailed computational study was done by density functional theory (DFT) calculations. A photoelectrochemical cell was assembled with optimized photoanode displayed 4-fold increase in photocurrent density as compared to pristine ZnO. The improved PEC performance is attributed to the synergistic effects, where the presence of Cr dopant improves the charge carrier density and enhanced electronic conductivity, and graphene has increased the carrier transport and collection efficiency. Overall, this study provides valuable insights into the development of (Cr-doped ZnO@Graphene) as a highly efficient and stable photoelectrode for practical applications in solar water splitting and renewable energy conversion.