Efficient Hydrogenation of Nitrobenzene to Aniline over a Palladium Carbide Nanocube Catalyst

Palladium is the most versatile and widely used metal for catalytic molecular transformations. Owing to its high cost and limited availability, there is a strong demand to improve its catalytic performance. In this study, we investigated the effect of carbidation on the catalytic performance of palladium nanocubes (Pd NCs) in the hydrogenation of nitrobenzene to aniline. Pd carbide NCs (PdCx NCs) exhibited high catalytic hydrogenation activity with a turnover frequency 39 times greater than that obtained using the pristine Pd NC catalyst. Control experiments, structural characterizations, and density functional theory calculations revealed that this significant enhancement is due to the improved H2 activation ability of PdCx NCs, resulting in the formation of polar hydrogen species and stronger adsorption of nitrobenzene on the catalyst surface. These findings elucidate the mechanisms by which carbidation improves the catalytic performance of Pd, broadening the application of Pd carbides in organic synthesis. This achievement also makes a significant contribution to the establishment of various efficient liquid-phase hydrogenation processes.