S-Doped Oriented Construction of {001} Facets Exposed BiOBr Nanosheets with Abundant Oxygen Vacancies and Promoted Visible-Light-Driven Photocatalytic Performance

Element doping and crystal engineering are efficient strategies to enhance the photo-reactivity of semiconductors by tuning the physico-chemical properties. Herein, S-doped BiOBr photocatalysts with tunable exposed {001} facets, were prepared by a hydrothermal method and characterized by XRD, XRF, BET, FT-IR, SEM, TEM, EDS, XPS, UV-vis DRS and EIS. It reveals S doping could orient the facet growth of BiOBr nanosheets from original exposed {010} plane towards {001}-dominant plane. The thiourea is selected as a “three-in-one” reaction media, which not only acts as a kind of ligand, capping agent and S donator, but also plays a crucial role on the oriented growth of exposed {001} facet BiOBr nanosheets. The photocatalytic activity of the obtained hybrids is evaluated by oxidizing RhB under visible light irradiation. S-doped BiOBr catalysts show significant improvement of photocatalytic activity compared with original BiOBr, which is attributed to the synergistic effect of S doping and {001} dominant facet growth, resulting in narrower bandgap energy, higher efficient charges separation and oxygen vacancies (OVs) concentration. This study provides a paradigm of crystal facet control by element doping, and gives a deep insight into the specific surface and properties determined doping element and crystal facet engineering.