Defect-Induced Metal Anchoring on BiOBr for Efficient Photocatalytic H2O2 Synthesis

Abstract

BiOBr, a representative layered visible-light-responsive semiconductor photocatalyst, has shown great potential for photocatalytic H2O2 production. However, its photocatalytic performance is severely restricted by the swift recombination of photogenerated charge carriers and the inadequate number of surface-active sites. In this work, abundant surface defects were introduced onto BiOBr via rapid joule heating with an ultrafast heating and cooling process, followed by the precise deposition of Ag nanoparticles through the vacancy-anchoring effect combined with an ultraviolet photoreduction method to construct an Ag/BiOBr-JH composite photocatalyst. The optimized Ag/BiOBr-JH exhibited an H2O2 production rate of 1540 μmol g–1 h–1, amounting to a 4.5-fold increase over pristine BiOBr. Mechanistic studies revealed that the surface defects on BiOBr suppressed charge-carrier recombination while serving as anchoring sites for Ag nanoparticles, and the deposited Ag acted as catalytic active sites, synergistically accelerating H2O2 production. Further density functional theory calculations showed that the composite catalyst not only moderates O2 adsorption to prevent site poisoning, but also lowers the energetic barrier for OOH* formation, collectively facilitating O2 activation. In addition, the vacancies introduced by rapid joule heating not only promoted the separation of photogenerated electrons and holes but also provided stable anchoring sites for Ag nanoparticles, whereas the deposited Ag further stabilized the vacancies through electronic interactions and participated in the catalytic reaction as additional active sites. The synergistic effect of defect engineering and metal modification effectively suppressed the severe charge recombination and limited active sites of pristine BiOBr. In this study, we demonstrate that integrating rapid joule heating with ultraviolet photoreduction serves as a robust strategy to boost the photocatalytic H2O2 evolution activity of BiOBr, while also offering a novel route for constructing high-performance BiOBr-derived photocatalysts.