Oxygen Vacancy-Rich 3D BiOBr Microtubes Promoting Exciton Dissociation for Efficient Photocatalytic H2O2 Production

Abstract

Rapid exciton dissociation into free charge carriers is essential for efficient semiconductor photocatalysis, yet high exciton binding energy often constrains photocarrier extraction. While defect creation and morphological tailoring are individually established strategies, their combined effect on exciton dynamics and carrier migration requires clarification. In this work, 3D mesoporous bismuth oxybromide microtubes with abundant oxygen vacancies were synthesized via a mannitolmediated hydrothermal route, effectively overcoming the intrinsic 2D anisotropic growth habit of BiOBr. Transient absorption spectroscopy, photoluminescence decay measurements, and density functional theory calculations demonstrate that the coupling of 3D tubular nanoconfinement and Ov defect states reduces exciton binding energy, accelerates exciton dissociation, and extends carrier lifetimes. Consequently, the optimized Ov-BiOBr microtubes display enhanced O2 adsorption capacity and superior photocatalytic H2O2 production, achieving an apparent quantum yield of 7.2% at 420 nm-a 14.4-fold increase over pristine BiOBr. This study demonstrates a practical defect-morphology co-engineering approach for modulating exciton dynamics in functional semiconductors.