One-step construction of {001} facet-exposed BiOCl hybridized with Al2O3 for enhanced molecular oxygen activation

{001} facet-exposed BiOCl with surface oxygen vacancies (SOVs) is developed via a facile ionic liquid (IL) self-combustion route using diethylamine hydrochloride (DLH, (C2H5)2NH·HCl) as a fuel and a source of the IL cation. It is found for the first time that an excess of DLH can not only facilitate the growth of {001} facets, but also create a reducing atmosphere for combustion, resulting in the release of oxygen atoms on the surface of BiOCl and thus the formation of SOVs. The existence of SOVs lifts the energy band potentials of BiOCl and narrows its energy band gap. To improve the separation efficiency of the photo-generated electrons and holes in BiOCl, amorphous Al2O3 is introduced to construct a heterojunction via an in situ combustion strategy by mixing their aqueous precursors. The heterostructured BiOCl/Al2O3 photocatalysts exhibit noticeable molecular oxygen activation and photocatalytic degradation of Rhodamine B. The conduction band (CB) position of amorphous Al2O3 is proposed for the first time, which matches well with that of BiOCl with SOVs and contributes to the effective transfer of electrons from BiOCl to Al2O3.