Interfacial Engineering and Charge Transfer of Layered BiOCl/BiOBr vdW Heterostructures by Ambient Hydrolysis

Abstract

Bismuth oxyhalides (BiOX) represent a class of layered semiconductor materials with unique [X–Bi–O–Bi–X] structures, offering promising tunability in optoelectronic properties via heterostructure construction. In this study, layered BiOCl/BiOBr van der Waals (vdW) heterostructures with tunable Cl/Br ratios were fabricated via a facile, energy‐efficient room‐temperature hydrolysis strategy. Systematic microstructural characterizations reveal the formation of well‐defined 2D nanosheet assemblies with intimate interfacial contact. Density functional theory (DFT) calculations reveal a work function difference between BiOCl (5.81 eV) and BiOBr (5.73 eV), which spontaneously drives interfacial electron redistribution, establishing a built‐in interfacial electric field (IEF). This IEF, corroborated by charge density difference analysis, facilitates the directional cross‐interface migration of photogenerated carriers, effectively enriching strongly reductive electrons in the conduction band (CB) of BiOBr and strongly oxidative holes in the valence band (VB) of BiOCl. Radical trapping experiments verify that the preserved holes (h+) act as the dominant active species, synergistically complemented by the photosensitization effect of RhB. Furthermore, the introduction of H2O2 as an electron scavenger further suppresses carrier recombination, maximizing hole utilization. The catalyst maintains robust structural stability over five cyclic runs. Consequently, the optimized heterostructure demonstrates significantly improved photocatalytic activity and robust structural stability. This work provides valuable insights into the interface engineering and charge‐transfer dynamics of bismuth oxyhalide semiconductor ceramics for optoelectronic applications.