Reconstructing Dual‐Induced {0 0 1} Facets Bismuth Oxychloride Nanosheets Heterostructures: An Effective Strategy to Promote Photocatalytic Oxygen Evolution

Sunlight‐driven photocatalytic water splitting to generate oxygen (O 2 ) is a promising approach for utilizing solar energy. Herein, direct Z‐scheme heterostructure photocatalysts composed of ultrathin Bi 3 O 4 Cl and BiOCl nanosheets are rationally fabricated via alkaline chemical etching and solvent exfoliation for O 2 evolution under visible light. With AgNO 3 and FeCl 3 as the electron scavenger, the optimized ultrathin Bi 3 O 4 Cl/BiOCl exhibits prominent photocatalytic activity for O 2 production under visible‐light illumination and the production rate (Fe 3+ : 58.6 µmol g −1  h −1 ) is much higher than the nanocrystal heterostructure (Fe 3+ : 28.5 µmol g −1  h −1 ). This ultrathin heterostructure system can efficiently transfer the electrons, which leads to a considerable improvement in the photocatalytic performance. Due to the suitable band edge potentials and the intense electronic interaction between two‐dimensional (2D) Bi 3 O 4 Cl and 2D BiOCl, as confirmed by theoretical computations, photoluminescence, and photoelectricity tests, the ultrathin heterojunction with an internal electric field has a highly remarkable charge transfer. The intimate interface contact and {0 0 1} facets effect promote the high photocatalytic performance of the ultrathin Bi 3 O 4 Cl/BiOCl heterostructure.