Simultaneous Phosphorylation and Bi Modification of BiOBr for Promoting Photocatalytic CO2 Reduction

Promoting photogenerated carriers separation and adjusting the activation path of the CO2 molecule are two effective solutions for improving the activity and selectivity of photocatalytic CO2 reduction. In this study, simultaneous phosphorylation and Bi modification are successfully introduced into BiOBr hierarchical spheres via a solvothermal reaction using red phosphorus as the additive. Remarkably, the synchronous phosphorylation and Bi modification of BiOBr lead to an improvement of CO2 conversion efficiencies, especially for the yield of CH4. Different characterization techniques were performed to explore the existence form of P and Bi modification, and the essence behind such an enhancement. Attributed to this in situ strategy, the regular hierarchical spheres morphology of BiOBr is preserved, and the Bi nanoparticles are well distributed with the average size of ca. 5 nm. Besides, the phosphorus exists in the form of BiPO4. The reasons for the enhanced photocatalytic activity are that the metal Bi modification could enhance the light harvesting and the selectivity of CH4; furthermore, the synchronous BiPO4 and Bi modification could improve the separation efficiency of photogenerated carriers and increase the surface charge transfer efficiency during the photocatalytic reaction process. We hope this work will provide a new perspective for fabrication of multivariate modification photocatalysts with highly efficient and highly selective photocatalytic CO2 reduction.