Construction of Multiple Asymmetric Catalytic Sites on Carbon Nitrides Toward Efficient Solar Hydrogen Peroxide Production.

Abstract

Solar-driven hydrogen peroxide (H₂O₂) production represents a sustainable alternative to energy-intensive industrial processes, yet its efficiency is hindered by poor charge separation and sluggish reaction kinetics. Here, a structurally adaptive strategy is proposed to create highly asymmetric multi-active-site architectures by synergistically integrating sulfur (S) dopants and single-atom zinc (Zn) species into the repeating units of 1D and 2D carbon nitride (C₃N₄) frameworks, i.e., C₃N₄ nanotube (CNT) and sheet (CNS). In this structure, S/Zn and N/O atoms contribute to the conduction and valence bands, respectively, providing multiple charge transfer pathways for photogenerated carriers to achieve efficient spatial separation. The electron delocalization promoted by the highly asymmetric configuration optimizes O₂ adsorption on Zn atoms and reduces the energy barrier for ^*OOH intermediate formation. Consequently, the optimized S-CNS-Zn and S-CNT-Zn catalysts exhibit remarkable H₂O₂ evolution rates of 1724 and 2708 µmol g^-1 h^-1, ≈72.1 and 17.5 fold higher than pristine C₃N₄, with an apparent quantum yield of 6.28% and 9.88% at 420 nm and solar-to-chemical conversion efficiency of 0.37% and 0.52%, respectively, surpassing most previously reported values. This work provides atomic insights for the design of multiple asymmetric catalytic sites.