Interfacial Effect of CNT-Supported Ultrafine Ru Nanoclusters on Efficient Transfer Hydrogenation of Nitroaromatic Compounds

Carbon nanotube (CNT)-supported ultrafine Ru nanoclusters with adjusted interfacial effects by N-doped carbon (Ru/CNT@CN) were synthesized by a facile 'impregnation-freeze-drying-thermal reduction' process. The introduced N-doped carbon not only increased the dispersity of the formed Ru nanoclusters (ultrafine average diameter of about 1.12 nm) but also contributed to obvious electronic transfer from the Ru species to the carbon-based supports (CNT@CN). Profiting from these interfacial effects, Ru/CNT@CN exhibited an excellent turnover frequency (TOF) of 643.6 min(-1) for hydrogen production from ammonia borane hydrolysis under neutral conditions at 298 K and a low activation energy of 27.15 kJ mol(-1), which was better than that of most Ru-based catalysts. More importantly, the Ru/CNT@CN catalyst showed ultrahigh catalytic activity and halogenated aniline selectivity (>99%) in the transfer hydrogenation of nitroaromatics due to the adsorption and activation of nitroaromatics on positively charged Ru sites, as revealed by density functional theory calculations. This work provides a high-efficiency catalyst for the transfer hydrogenation of nitroaromatics based on the regulation of interfacial effects between Ru nanoclusters and supports.