Tailoring of electronic and surface structures boosts exciton-triggering photocatalysis for singlet oxygen generation

Arising from reduced dielectric screening, excitonic effects should be taken into account in ultrathin two-dimensional photocatalysts, and a significant challenge is achieving nontrivial excitonic regulation. However, the effect of structural modification on the regulation of the excitonic aspect is at a comparatively early stage. Herein, we report unusual effects of surface substitutional doping with Pt on electronic and surface characteristics of atomically thin layers of Bi₃O₄Br, thereby enhancing the propensity to generate ¹O₂ Electronically, the introduced Pt impurity states with a lower energy level can trap photoinduced singlet excitons, thus reducing the singlet-triplet energy gap by ∼48% and effectively facilitating the intersystem crossing process for efficient triplet excitons yield. Superficially, the chemisorption state of O₂ causes the changes in the magnetic moment (i.e., spin state) of O₂ through electron-mediated triplet energy transfer, resulting a spontaneous spin-flip process and highly specific ¹O₂ generation. These traits exemplify the opportunities that the surface engineering provides a unique strategy for excitonic regulation and will stimulate more research on exciton-triggering photocatalysis for solar energy conversion.