Vacancy associates promoting solar-driven photocatalytic activity of ultrathin bismuth oxychloride nanosheets

TLDR: High solar photocatalytic activity in ultrathin BiOCl nanosheets with almost fully exposed active {001} facets is achieved and some new and deep-seated insights are provided into how the defects in the exposed active facets affect the solar-driven photoc atalytic property are provided.

Abstract: Crystal facet engineering of semiconductors is of growing interest and an important strategy for fine-tuning solar-driven photocatalytic activity. However, the primary factor in the exposed active facets that determines the photocatalytic property is still elusive. Herein, we have experimentally achieved high solar photocatalytic activity in ultrathin BiOCl nanosheets with almost fully exposed active {001} facets and provide some new and deep-seated insights into how the defects in the exposed active facets affect the solar-driven photocatalytic property. As the thickness of the nanosheets reduces to atomic scale, the predominant defects change from isolated defects VBi‴ to triple vacancy associates VBi‴VO••VBi‴, which is unambiguously confirmed by the positron annihilation spectra. By virtue of the synergic advantages of enhanced adsorption capability, effective separation of electron–hole pairs and more reductive photoexcited electrons benefited from the VBi‴VO••VBi‴ vacancy associates, the ultrathin Bi...