Cooperative catalytic performance of bimetallic Ni-Au nanocatalyst for highly efficient hydrogenation of nitroaromatics and corresponding mechanism insight

HNO3-modified carbon black supported Ni-Au bimetallic nanocatalysts (HCB-Ni-Au) with different Ni/Au molar ratio were synthesized for hydrogenation of nitroaromatics. The synergistic effect between bimetallic nanoparticles and HCB, Ni and Au nanoparticles improved the catalytic efficiency. The reaction mechanism and pathway investigation exhibited that nitroaromatics were reduced by cleavage of NO bond and azo linkage (NN) and uptake of H from NiH and AuH bonds. Density functional theory theoretical calculation showed 4-nitrophenol (4-NP) with higher free energy was easier to be catalyzed. The activation of enthalpy for MO was 65.7 kcal mol−1, which displayed the highest catalytic rate of 2.1055 min−1. Meanwhile, the reaction rate of 4-NP hydrogenation catalyzed by HCB-Ni6-Au1 reached 1.9617 min−1, which was 15 and 38 times higher than that of Ni and Au monometallic nanocatalyst, respectively. HCB-Ni6-Au1 with good structural stability could be well reused and applied in tap, distilled, river, and lake water samples.