Ag-Modified BiOCl Single-Crystal Nanosheets: Dependence of Photocatalytic Performance on the Region-Selective Deposition of Ag Nanoparticles

For single-crystal photocatalysts, selective deposition of noble metals as electron cocatalysts has been demonstrated to be an effective method to improve their photocatalytic performance. However, the effect of the selective deposition location of noble metals on the photocatalytic performance of single-crystal photocatalysts has not been really revealed, because the noble metals can only be selectively deposited on the electron enrichment facets and cannot be modified on the hole-enrichment facets due to the absence of effective deposition methods. In this study, a photosensitization-deposition strategy, as a new selective deposition method, has been developed to selectively deposit Ag nanoparticles on the hole-enrichment regions (the lateral surfaces) of BiOCl single-crystal nanosheets (referred to as Ag/BiOCl(Dye)), and the effect of selective-deposition locations of Ag nanoparticles on the photocatalytic performance of BiOCl single-crystal photocatalysts has been investigated. For comparison, Ag nanoparticles were-also selectively deposited on the electron-enrichment regions (the outer-ring regions of dominant exposed {001} facets) of BiOCl nanosheets (referred to as Ag/BiOCl(UV)) by the usual photocatalytic-deposition method, and were randomly deposited on the whole surface of BiOCl nanosheets (referred to as Ag/BiOCl(NaBH4)) by a direct reduction method. It was found that the Ag/BiOCl(UV) photocatalysts with selective deposition of Ag nanoparticles on the electron-enrichment regions exhibited the highest photocatalytic performance; while Ag/BiOCl(Dye) with selective deposition of Ag nanoparticles on the hole-enrichment regions displayed the lowest efficiency, even lower than the unmodified BiOCl nanosheets. On the basis of our present results, a possible mechanism was proposed to account for the completely different photocatalytic performance of BiOCl nanosheets with site-selective deposition of Ag nanoparticles. This work may provide new insights into the flexible design and preparation of various high-performance photocatalytic materials.