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Hydrogen peroxide (H2O2) is an essential and versatile oxidant. The photocatalytic production of H2O2 is a promising alternative to the conventional anthraquinone oxidation process. In this work, BiOBr nanosheets with oxygen vacancies (OVs) were successfully synthesized by a solvothermal method in the presence of mannitol. The character of the nanosheets shortened the diffuse length of charge carriers, which is beneficial for the charge separation. The introduction of OVs enhanced the visible light absorption and also improved the carrier separation. Furthermore, OVs enhanced the activation of O2 molecules and facilitated the generation of ˙O2−. As a result, the products exhibited good performance in photocatalytic H2O2 production. After introducing HCOOH, the yield of H2O2 was further enhanced by a factor of 50, from 3 μmol h−1 to 150 μmol h−1. This work provides a reference to design high performance photocatalysts for H2O2 production through defect engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • A considerable productivity and selectivity of methanol (180.75 μmol·g cat −1·h−1, 80.07 %) are achieved. • Cl− could be transformed into Cl over BiOCl-O v to efficiently activate methane. • The in situ produced Cl is constrained on the surface of BiOCl-O v , inhibiting over halogenation. • Reactive oxygen species produced by H 2 O 2 dissociation are utilized to be the receptors of CH 3. Selective partial oxidation of methane to methanol under mild conditions remains a great challenge in activating the first C H bond of CH 4 and inhibiting overoxidation. Chlorine-mediated pathway arises as a promising strategy to obtain high CH 4 conversion under mild conditions. Herein, a considerable CH 3 OH production rate of 180.75 μmol·g cat −1·h−1 with 80.07 % selectivity is achieved when the BiOCl with oxygen vacancies is irradiated by visible light in NaCl solution with H 2 O 2 addition. Experimental studies reveal that chlorine radicals are in situ produced and constrained on the surface of the catalyst, which inhibits the over halogenation. Reactive oxygen species produced by H 2 O 2 dissociation were utilized to be the receptors of CH 3. The high productivity of methanol was achieved by the synergy effect of chlorine radicals and H 2 O 2. This work provides a new feasible method to convert inert methane into high-value-added products via photocatalysis. [ABSTRACT FROM AUTHOR]