Lattice Match‐Enabled Covalent Heterointerfaces with Built‐in Electric Field for Efficient Hydrogen Peroxide Photosynthesis

Abstract Crafting semiconducting heterojunctions represents an effective route to enhance photocatalysis by improving interfacial charge separation and transport. However, lattice mismatch ( δ ) between different semiconductors can significantly hinder charge dynamics. Here, meticulous lattice tailoring is reported to create a covalent heterointerface with a built‐in electric field (BIEF), imparting markedly improved hydrogen peroxide (H 2 O 2 ) photosynthesis. Specifically, an In 2 S 3 /CdS heterojunction with a coherent heterointerface, characterized by covalent In─S─Cd bridge and exceptionally low lattice mismatch of 0.27%, and a BIEF from In 2 S 3 to CdS, is rationally designed. This heterojunction entails rapid charge separation and transfer, achieving an outstanding H 2 O 2 production rate of 2.09 mmol g −1 h −1 without the need for scavengers and oxygen bubbling, and a high apparent quantum efficiency of 17.73% at 400 nm. Density functional theory (DFT) calculations further reveal that this Z‐scheme heterojunction facilitates the adsorption of * O 2 and the generation of * OOH intermediates during the 2e − oxygen reduction reaction, associated with a low Gibbs free energy. This study underscores the significance of fine‐tuning interfacial lattices and integrating BIEF to accelerate photocatalysis. The simple yet robust strategy can be conveniently leveraged to enhance device performance in optoelectronics, electrocatalysis, photoelectrocatalysis, and sensing.