Multiphase interface engineering in Bi4O4SeCl2-based ceramics for enhanced light-driven hydrogen evolution via interfacial charge regulation.

Multiphase interface engineering provides an effective strategy for regulating interfacial charge transfer and improving light-driven catalytic energy conversion. Here, Te-incorporated Bi4O4SeCl2 hybrid ceramics containing retained BiOCl and β-Bi2O3 phases together with Te-induced conductive Bi2Te3 nanophases are constructed to generate abundant coherent and semi-coherent interfaces. These multiphase interfaces effectively reconstruct the electronic structure and microstructure of the Bi4O4SeCl2 matrix, leading to optimized carrier transport pathways, broadened visible-NIR absorption, and improved interfacial charge separation. The optimized composite exhibits enhanced electrical transport while maintaining low thermal conductivity due to intensified phonon scattering at heterogeneous interfaces. Density functional theory calculations reveal pronounced work-function-driven electron transfer at the Bi4O4SeCl2/BiOCl interface, whereas the Bi4O4SeCl2/Bi2Te3 junction forms a quasi-ohmic contact that facilitates rapid electron exchange. Electrochemical impedance spectroscopy and electron paramagnetic resonance measurements further demonstrate reduced charge-transfer resistance and regulated oxygen-vacancy-associated defect states at the optimized composition. Under illumination, the engineered interfaces promote efficient separation and migration of photogenerated carriers. Consequently, the optimized hybrid catalyst achieves a hydrogen evolution rate of 85.74 μmol g-1 h-1, representing a 287% enhancement compared with pristine BiOSeCl-0Te. These results establish multiphase interface engineering as an effective route for regulating interfacial charge-transfer pathways and light-driven hydrogen evolution in layered bismuth-based materials.