Low-Temperature Growth of AgBr Nanoplates via Concerted Etching and Redeposition Processes

Inorganic nanocrystals with sophisticated shape control can be synthesized by considering not only crystal growth but also etching process. Herein, a shape control method involving an etching process at low temperature for AgBr nanocrystal, an excellent visible-light responsive material, is reported. The addition of polyvinylpyrrolidone (PVP) to an aqueous solution containing excess Br⁻ ions in which irregularly shaped AgBr nanoparticles are dispersed transforms the nanoparticles into nanoplates at room temperature. Detailed electron microscopic observations of the shape during transformation and quantitative analyses of the Ag⁺ ion concentration reveal preferential etching of {111} planes of the irregularly shaped nanoparticles and subsequent redeposition of AgBr on other crystalline planes, resulting in the formation of nanoplates. The obtained AgBr nanoplates show higher visible-light photocatalytic activity than irregularly shaped nanoparticles, since nanoplates are almost enclosed by {111} planes with active catalytic reaction sites.