Bound-state electrons synergy over photochromic high-crystalline C3N5 nanosheets in enhancing charge separation for photocatalytic H2 production

Abstract

Solar-driven water splitting for photocatalytic hydrogen evolution is considered a highly promising and cost-effective solution to achieve a stable renewable energy supply. However, the sluggish kinetics of electron-hole pairs’ separation poses challenges in attaining satisfactory hydrogen production efficiency. Herein, we synthesized the exceptional performance of highly crystalline C₃N₅ (HC–C₃N₅) nanosheet as a photocatalyst, demonstrating a remarkable hydrogen evolution rate of 3.01 ​mmol ​h⁻¹ ​g⁻¹, which surpasses that of bulk C₃N₅ (B–C₃N₅) by a factor of 3.27. Experimental and theoretical analyses reveal that HC-C₃N₅ nanosheets exhibit intriguing macroscopic photoinduced color changes, effectively broadening the absorption spectrum and significantly enhancing the generation of excitons. Besides, the cyano groups in HC-C₃N₅ efficiently captures and converts photoexcited electrons into bound states, thereby prolonging their lifetimes and effectively separating electrons and holes into catalytically active regions. This research provides valuable insights into the establishment of bound electronic states for developing efficient photocatalysts.