One-step: In situ synthesis of BiOCl/(BiO)₂CO₃ composite photocatalysts with exposed high-energy {001} facets

Tailoring the chemical composition and morphology of a composite photocatalyst is a key way to achieve superior photocatalytic activity. In this work, a simple method has been developed to controllably prepare BiOCl/(BiO)₂CO₃ composite photocatalysts with exposed {001} facets. The chemical composition and morphology of the BiOCl/(BiO)₂CO₃ composites can be easily tuned by simply changing the ethanol/water volume ratio in the initial reaction system. The precursor of guanidine hydrochloride not only acts as the source of chloride and carbonate ions to form the BiOCl/(BiO)₂CO₃ composites, but also acts as the crystal growth inhibitor to control the growth of BiOCl nanosheets. The composites exhibit superior photocatalytic activity towards the degradation of rhodamine B under visible light irradiation, which can be ascribed to the type-II band alignment and intimate interfacial contacts between BiOCl nanosheets and (BiO)₂CO₃ nanoparticles, as well as their exposed high-energy facets. Both the formation mechanism of the BiOCl/(BiO)₂CO₃ composite and the photocatalytic degradation mechanism have been investigated and proposed.