In situ reversible assembly of atomic interfacial structure in BiOI/Bi₅O₇I p-n heterojunctions to promote visible-light photocatalysis

Constructing efficient p-n heterojunctions holds great potential in the realm of photocatalysis for promoting the sustainable development of the environment and energy industries. However, traditional p-n heterojunctions suffer from limited interfacial interaction which severely restricts the effectiveness of the built-in electric field in boosting charge separation. Herein, we present an in situ reversible assembly approach to fabricate functional p-n junction in BiOI/Bi5O7I composites at room temperature. By controlling the reaction time or the amount of KI precursor added, we attain the as-designed BiOI@Bi5O7I and Bi5O7I@BiOI heterojunctions with large specific surface area and ample interfacial electric field. Subsequent application of the optimized heterojunction material as visible-light photocatalyst achieves efficient photoreduction of CO2 reactant into CO product (0.46 mu mol g(-1)h(-1)), even without using any sacrificial agent in the gas-solid reaction system. This catalytic performance is notably similar to 6.6 times and 15.3 times higher than that of standalone BiOI and Bi5O7I materials, respectively. In situ XPS, in situ Kelvin probe force microscopy, and theoretical calculations reveal that the built-in electric field induces directional charge transfer to greatly boosts the efficiency of separating photogenerated electron-hole pairs at the interface of BiOI and Bi5O7I. This study provides valuable insights for the rational design and straightforward fabrication of next-generation, integrated heterostructured photoelectronic materials for efficient energy, environmental, and chemical applications.