Interfacial B-O bonding modulated S-scheme B-doped N-deficient C3N4/O-doped-C3N5 for efficient photocatalytic overall water splitting

Abstract

Photocatalytic overall pure water splitting is a promising method for generating green hydrogen energy under mild conditions. However, this process is often hindered by sluggish electron-hole separation and transport. To address this, a step-scheme (S-scheme) B-doped N-deficient C₃N₄/O-doped C₃N₅ (BN-C₃N₄/O-C₃N₅) heterojunction with interfacial B-O bonds has been constructed. Utilizing Pt and Co(OH)₂ as co-catalysts, BN-C₃N₄/O-C₃N₅ S-scheme heterojunction demonstrates significantly enhanced photocatalytic activity for overall pure water splitting under visible light, achieving H₂ and O₂ evolution rates of 40.12 and 19.62 µmol/h, respectively. Systematic characterizations and experiments revealed the performance-enhancing effects of the enhanced built-in electric field and the interfacial B-O bonding. Firstly, the strengthened built-in electric field provides sufficient force for rapid interfacial electron transport. Secondly, by reducing the transport energy barrier and transfer distance, the interfacial B-O bonds facilitate rapid recombination of electrons and holes with relatively low redox potential via the S-scheme charge-transfer route, leaving the high-potential electrons and holes available for H⁺ reduction and OH⁻ oxidation reactions. Overall, the photocatalytic efficiency of BN-C₃N₄/O-C₃N₅ S-scheme heterojunction was significantly improved, making it a promising approach for green hydrogen production through overall pure water splitting.