4‐Nitrophenol Reduction by a Single Platinum Palladium Nanocube Caged within a Nitrogen‐Doped Hollow Carbon Nanosphere

The improvement of the utilization efficiency and the enhancement of the catalytic activity and stability of precious-metal-based nanocatalysts is a hot topic in the field of catalysis. In the present study, a single-nanoparticle catalyst with a high stability is realized by confining a single surface-cleaned PtPd alloy nanocube within a N-doped hollow carbon nanosphere (PtPd@N-HCS). The microporous carbon shell makes the encaged PtPd nanocube accessible to the reacting molecules. Compared with PtPd nanocubes protected by polyvinylpyrrolidone (PVP-PtPd) and N-doped carbon spheres, PtPd@N-HCS exhibited a better catalytic performance towards 4-nitrophenol reduction. Under the catalysis of PtPd@N-HCS, 4-nitrophenol can be reduced completely to 4-aminophenol (100 %) in 2 min; however, only 50 and 20 % of 4-nitrophenol was degraded in 2 min with PVP-PtPd and N-HCS as catalysts. Moreover, as a result of the confinement of PtPd nanocubes in hollow nanospheres, PtPd@N-HCS showed a high catalytic stability with 100 % conversion maintained over at least four cycles.