Synergistic Dual Active-Site Engineering on C ₃ N ₄ for Highly Efficient and Stable Photocatalytic Overall Water Splitting

As a well-established photocatalyst responsive to visible light, C3N4 exhibits substantial potential in the field of overall water splitting. However, efficiency and stability are the two key points for C3N4 photocatalysts because their application has been seriously restricted due to a serious photocorrosion issue and the recombination of photogenerated charge pairs. In this work, dual active-site cocatalysts comprising Pt@Cr2O3 and MnOx were precisely constructed on the surface of C3N4. The resulting Cr2O3/Pt/C3N4/MnOx composite photocatalyst exhibited remarkably enhanced photocatalytic stability. The H2 evolution rate of the composite reached 4.38 μmol·h–1, which is approximately 56 times higher than that of Pt/C3N4 (0.078 μmol·h–1). Detailed mechanistic studies reveal that the introduction of MnOx onto Pt/C3N4 facilitates charge carrier transfer, promotes the timely decomposition of newly formed peroxides, and significantly improves the corrosion resistance of C3N4. Meanwhile, the presence of Cr2O3 effectively suppresses the reverse reaction between hydrogen and oxygen, thereby further enhancing the overall water-splitting efficiency. This work provides novel insights for the design and development of highly efficient and stable C3N4-based photocatalysts for sustainable solar-driven water splitting.