Cooperative tungsten centers in polymeric carbon nitride for efficient overall photosynthesis of hydrogen peroxide

Abstract

The artificial photosynthesis of hydrogen peroxide (H₂O₂) is of great interest, yet simultaneously boosting the oxygen reduction reaction (ORR) while maintaining an efficient water oxidation reaction (WOR) poses a significant challenge. Herein, we present an innovative strategy to construct precisely engineered photocatalysts with adjacent dual active sites, which effectively promote both the ORR and WOR. Specifically, isolated tungsten (W) atoms are strategically positioned next to the triazine rings of polymeric carbon nitride, creating synergistic reactive regions with complementary ORR and WOR activities. Through a combination of experimental investigations and theoretical simulations, we demonstrate that by tuning the isolated W species, the adjacent coordinating triazine units can activate a highly selective two-electron ORR pathway, facilitating the production of H₂O₂. Simultaneously, the WOR occurs at the dedicated W site, and the in situ generated O₂ is rapidly consumed by the adjacent ORR active sites. This interplay between the two active sites is crucial for improving the overall reaction kinetics. The optimized catalyst exhibits exceptional performance, with a high activity of 556 μmol g⁻¹ h⁻¹ for overall H₂O₂ production with an apparent quantum yield of 8.53% and a remarkable solar-to-chemical conversion efficiency of 0.31%, outperforming most previously reported catalysts under similar conditions. The promising efficiency in H₂O₂ generation, accomplished through the intricate design of catalysts with cooperative dual sites, broadens the avenue for converting solar energy into valuable chemical products in a sustainable and environmentally friendly manner.