Engineering dual-interface ternary heterojunctions: A synergy of S-scheme and Ohmic contact for enhanced charge transfer to improve photocatalytic efficiency

Competent interfacial charge transfer and robust interface interactions are critical for achieving superior spatial separation of charge carriers and establishing advanced heterogeneous photocatalysts. This paper presents a novel multi-interface heterojunction photocatalyst based on ZIF-67, g-C₃N₄ and MXene, which is synthesized via a simple coprecipitation method that integrates the S-scheme and Ohmic contact charge transfer mechanisms. The unique architecture features an S-scheme junction at the ZIF-67/g-C₃N₄ interface and an Ohmic junction between ZIF-67 and MXene, resulting in dual internal electric fields (IEFs) that enhance photocarrier separation, suppress electron-hole recombination, and provide efficient charge transfer pathways. Specifically, the S-scheme charge transfer mechanism facilitates efficient charge separation and maximizes redox capabilities, while the Ohmic contact mechanism supports high electron transfer efficiency with almost zero resistance. These synergistic charge dynamics significantly boost the photocatalytic performance in key applications, including Cr (VI) reduction, tetracycline degradation, and hydrogen evolution, thus achieving a maximum IPCE of 55%. Comprehensive characterizations, including photoluminescence spectroscopy, electrochemical impedance spectroscopy, and photocurrent analyses, confirmed the superior charge separation and light utilization of the system. Furthermore, reusability studies highlighted the stability of the catalyst, thus demonstrating its potential for real-world environmental and energy applications. This study improves the understanding of dual-interface charge-transfer mechanisms and offers a promising strategy for designing high-performance photocatalysts for sustainable environmental remediation and renewable energy production.