Design of an ultrasmall Au nanocluster–CeO2 mesoporous nanocomposite catalyst for nitrobenzene reduction

Abstract

In this work we are inspired to explore gold nanoclusters supported on mesoporous CeO₂ nanospheres as nanocatalysts for the reduction of nitrobenzene. Ultrasmall Au nanoclusters (NCs) and mesoporous CeO₂ nanospheres were readily synthesized and well characterized. Due to their ultrasmall size, the as-prepared Au clusters can be easily absorbed into the mesopores of the mesoporous CeO₂ nanospheres. Owing to the unique mesoporous structure of the CeO₂ support, Au nanoclusters in the Au@CeO₂ may effectively prevent the aggregation which usually results in a rapid decay of the catalytic activity. It is notable that the ultrasmall gold nanoclusters possess uniform size distribution and good dispersibility on the mesoporous CeO₂ supports. Compared to other catalyst systems with different oxide supports, the as-prepared Au nanocluster–CeO₂ nanocomposite nanocatalysts showed efficient catalytic performance in transforming nitrobenzene into azoxybenzene. In addition, a plausible mechanism was deeply investigated to explain the transforming process. Au@CeO₂ exhibited efficient catalytic activity for reduction of nitrobenzene. This strategy may be easily extended to fabricate many other heterogeneous catalysts including ultrasmall metal nanoclusters and mesoporous oxides.