Insight into Catalytic Mechanisms for the Reduction of Nitrophenol via Heterojunctions of Gold Nanoclusters on 2D Boron Nitride Nanosheets

Gold nanoclusters were synthesized and homogeneously distributed on boron nitride nanosheets (BNNSs) to form AuNC@BNNSs nanohybrids. Compared to pure gold nanoclusters, the nanohybrid not only exhibits much better catalytic activity for the reduction of 4-nitrophenol (4-NP), but also prevents gold nanoclusters from aggregation. We found that the catalytic performance of AuNC@BNNSs nanohybrid increased with decreasing pH and increasing temperature of the reaction environment. The catalytic mechanism of the nanohybrid was thoroughly explored by density functional theory (DFT). It was concluded that the catalytic activity should be caused by repeated electron transfer on HOMO between 4-NP and BNNSs, which was mediated by the surface-bound gold nanoclusters. Furthermore, it was observed that the actual reducing agent is molecular hydrogen rather than borohydride. The present methodology could be generalized to the synthesis of other metallic nanoparticle@BNNSs nanohybrids as promising heterogeneous catalysts for varied catalytic reactions.