Tuning Pt surface adsorption energy with a Cr2O3 thin layer for efficient photocatalytic overall water splitting

Abstract

Visible-light-driven one-step excitation photocatalytic overall water splitting (OWS) under ambient pressure constitutes a sustainable route for the conversion of inexhaustible solar energy into clean hydrogen energy. Although graphitic carbon nitride (C₃N₄) possesses both visible-light responsiveness and a moderate band structure, its catalytic efficiency is drastically hampered by the rapid recombination of photoexcited carriers and inevitable hydrogen–oxygen reverse reactions. To overcome these critical bottlenecks, a Cr₂O₃/Pt/C₃N₄ catalyst was successfully constructed via in situ photodeposition. Notably, the as-prepared Cr₂O₃/Pt/C₃N₄ catalyst enables efficient visible-light-driven one-step excitation OWS, exhibiting a catalytic activity 4 times superior to that of pristine Pt/C₃N₄. Combining density functional theory (DFT) calculations and structural characterization, it was found that the in situ deposited Cr₂O₃ protective layer on the cocatalyst effectively modulates the electronic structure and adsorption energy of Pt, thereby inhibiting the oxygen–hydrogen recombination reaction and enabling stable and efficient hydrogen production. This work thereby lays a theoretical foundation and offers technical pathways for the design strategy and application exploration of highly efficient C₃N₄-based photocatalysts.