Interface‐Engineered C ₄ N/MgAl‐LDH Heterostructure for High‐Performance Photocatalytic H ₂ O ₂ Production

Abstract Photocatalytic production of hydrogen peroxide (H 2 O 2 ) 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 H 2 O 2 photocatalysts. Herein, we constructed an interface‐engineered C 4 N/MgAl‐LDH heterostructure via a straightforward in situ electrostatic self‐assembly method. The resulting hybrid photocatalyst exhibits a remarkable H 2 O 2 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, C 4 N, 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 H 2 18 O and 18 O 2 provide clear evidence for dual pathways of H 2 O 2 formation involving both water and molecular oxygen. The incorporation of C 4 N 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 H 2 O 2 production.