BiOBr/COF S-scheme photocatalyst for H2O2 production via concerted two-electron pathway

Constructing step-scheme (S-scheme) heterojunctions has become a popular strategy for efficient photocatalytic H2O2 generation. Herein, we in situ grew BiOBr nanosheets (NSs) on a Schiff-base covalent organic framework (COF) with large π-conjugated structures to prepare S-scheme BiOBr/COF photocatalysts for H2O2 synthesis. The highest photocatalytic H2O2 production performance of the composite sample constituting the S-scheme heterojunction is 3749 µmol g−1 h−1, which was 1.85 and 27 times the rates of COF and BiOBr, respectively. The construction of S-scheme heterojunction contributed to efficient carrier transfer and separation in space and enhanced redox power. Moreover, the lying-down O2-adsorption configuration on the COF surface favors the concerted two-electron O2 reduction process, which greatly reduced the reduction potential requirement for O2-to-H2O2 conversion. The synergy between the S-scheme heterojunction and the unique O2–COF interaction boosted photocatalytic H2O2 production activity.