Get access

AgBr Nanocrystals from Plates to Cubes and Their Photocatalytic Properties



AgBr nanocrystals, evolving from plates through truncated cubes and finally to regular cubes, corresponding to a progressive shrinkage of exposed {1 1 1} facets and enlargement of exposed {1 0 0} facets, were successfully prepared by facile ion-exchange reactions under the synergistic effects of polyvinylpyrrolidone and NH3 H2O. An investigation of the growth mechanism revealed that polyvinylpyrrolidone can selectively adsorb on the {1 1 1} facets of AgBr nanocrystals, whereas NH3H2O not only forms a [Ag(NH3)2]+ complex that slows the rates of ion-exchange reactions, but may also prefer to adsorb on {1 0 0} facets. Studies of their photocatalytic properties showed that the as-prepared AgBr nanocrystals exhibited facet-dependent photocatalytic properties. The {1 1 1}-dominated AgBr nanoplates exhibited the highest photocatalytic activities, and the photodegradation rate of methyl orange dyes over them was 3 times faster than over AgBr nanocubes that expose {1 0 0} facets. Surface atomic models and DFT calculations indicate that the {1 1 1} facets have more dangling bonds and a higher surface energy than the {1 0 0} facets, which substantiate the facet-dependent photocatalytic properties. Therefore, our work not only provides a novel method to prepare regular AgBr nanocrystals, but also demonstrates that the shape and exposed facets have important influence on their photocatalytic activities.

Get access to the full text of this article