Interface-Engineered C₄N/MgAl-LDH Heterostructure for High-Performance Photocatalytic H₂O₂ Production

Photocatalytic production of hydrogen peroxide (H₂O₂) from water and air offers a highly promising and sustainable strategy. However, the slow kinetics of water oxidation severely restricts the oxygen reduction half-reaction due to insufficient proton supply, leading to low efficiency of many H₂O₂ photocatalysts. Herein, we constructed an interface-engineered C₄N/MgAl-LDH heterostructure via a straightforward in situ electrostatic self-assembly method. The resulting hybrid photocatalyst exhibits a remarkable H₂O₂ yield rate of 2.38 mmol g^-1 h^-1 without cocatalysts and sacrificial agents, along with exceptional stability (≥20 cycles). Its performance significantly surpasses those of bare MgAl-LDH, C₄N, and their physically mixed counterpart. The zeta potential analysis confirms the formation of an intimately contacted interface with strong electronic coupling, enabling rapid charge transfer and prominent photocatalytic performances. Isotope tracing experiments employing H₂ ¹⁸O and ¹⁸O₂ provide clear evidence for dual pathways of H₂O₂ formation involving both water and molecular oxygen. The incorporation of C₄N not only extends visible-light absorption but also promotes the adsorption and activation of key reactants and intermediates. The synthetic approach developed here is simple, cost-effective, and broadly applicable, offering a feasible route for designing advanced photocatalysts for high-efficiency H₂O₂ production.