Fe─N₅-Induced Coordination Engineering of Mo Single-Atom: Dual Sites Synergistically Enhancing Photocatalytic H₂O₂...

The photo-Fenton technique is a promising strategy for eliminating recalcitrant organic pollutants, coupling photocatalytic two-electron oxygen reduction (2e^- ORR) for hydrogen peroxide (H₂O₂) generation with subsequent activation of H₂O₂ to hydroxyl radicals (^•OH) via the one-electron (1e^-) Fenton process. To solve the distinct favorable active sites and mismatched selectivity between 2e‒ oxygen reduction reaction and 1e^‒ Fenton process, we propose a Fe─N₅-induced coordination engineering strategy of Mo single-atom to prepare Fe-Mo_SA/ultra-thin carbon nitride (UCN) photocatalysts, achieving a H₂O₂ production rate of 2585.40 μmol g^-1 h^-1 in pure water under ambient air and >99% degradation of Rhodamine B under natural sunlight. The excellent performance of Fe-Mo_SA/UCN for H₂O₂ generation and activation thanks to the optimized the charge dynamics and the synergistic effect of dual sites. Theoretical calculations evidence that regulated Mo─N₃ greatly facilitate O₂ adsorption and reduce the energy barrier of 2e^- ORR. The generated H₂O₂ spontaneously migrates to the introduced Fe─N₅ sites for in situ activation to generate ^•OH. Furthermore, outdoor and continuous-flow experiments also demonstrate the excellent practical applicability of Fe-Mo_SA/UCN. Overall, this study demonstrates the great potential of dual-active-site modulation in advancing photo-Fenton catalysis, providing atomic-level insights for designing high-performance solar energy conversion systems.