Fining Crystal Facet and Oxygen Vacancy Engineering of Bifunctional BiOBr Facilitates Excellent Photocatalytic Hydrogen Evolution and Phenol Hydroxylation

O decomposition ability of BiOBr(001) with OVs. OVs increase the carrier concentration of the (010) crystal facet, while theoretical calculations reveal that OVs greatly suppress the carrier recombination probability on the (001) crystal facet. Here, we propose that the "hydroxyl blocking effect" on the (001) crystal facet of BiOBr is responsible for the low HER and phenol hydroxylation activities. By optimizing hydroxyl adsorption free energy via OVs, the conversion rate of phenol hydroxylation over the (001) crystal facet with OVs can be achieved at 99.2%. This work offers the fundamental understanding required to improve the photocatalytic efficiency of BiOBr and related photocatalysts by introducing oxygen vacancies (OVs) and altering the crystal facets.