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

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.