Insights into Dynamic Surface Bromide Sites in Bi4O5Br2 for Sustainable N2 Photofixation

Abstract

Simulating photosynthesis has long been one of the ideas for realizing the conversion of solar energy into industrial chemicals. Heterogeneous N₂ photofixation in water is a promising way for sustainable production of ammonia. However, a mechanistic understanding of the complex aqueous photocatalytic N₂ reduction is still lacking. In this study, a light-dependent surface hydrogenation mechanism and light-independent protection of catalyst surface for N₂ reduction are revealed on ultrathin Bi₄O₅Br₂ (BOB) nanosheets, in which the creation and annihilation of surface bromine vacancies can be controlled via a surface bromine cycle. Our rapid scan in situ FT-IR spectra verify that photocatalytic N₂ reduction proceeds through an associative alternating mechanism on BOB surface with bromine vacancies (BrV-BOB). This work provides a new strategy to combine light-dependent facilitated reaction with light-independent regeneration of catalyst for advancing sustainable ammonia production.