Nitrogen-doped carbon black supported NiCo2S4 catalyst for hydrogenation of nitrophenols under mild conditions

Catalytic hydrogenation of nitrophenols to aminophenols was considered as the most efficient way to solve their contamination together with huge economic benefit. NiCo2S4 can be used not only as supercapacitor materials, but also competitive catalytic materials in hydrogenation reactions. In this work, a nitrogen-doped carbon black (NCB) supported NiCo2S4 catalyst is successfully prepared by a facile one-pot solvothermal approach. TEM results show that the ultrafine NiCo2S4 particles are uniformly dispersed on the surface of NCB at a low NiCo2S4 loading, while aggregation may occur in NiCo2S4/NCB catalysts with an excessive NiCo2S4 content. The NiCo2S4-30/NCB catalyst with a BET surface area of 47.20 m2 g−1 exhibits the most excellent catalytic activity and durability for heterogeneous catalytic hydrogenation of nitrophenols using NaBH4 as the reducing agent at 30 °C in the aqueous solution. The kinetic constant of hydrogenation of p-nitrophenol catalyzed by NiCo2S4-30/NCB is almost five times higher than the reaction catalyzed by pristine NiCo2S4. The outstanding performance of NiCo2S4-30/NCB is ascribed to the unique nanostructure of the catalyst and the combined effect between the NiCo2S4 and NCB, including abundant surface functional groups of NCB for anchoring and dispersing NiCo2S4, strong adsorption ability for nitrophenol molecules facilitated by π–π stacking interaction, as well as fast electron transfer from NCB to NiCo2S4, resulting in higher local electron densities and thus facilitating the uptake of electrons by nitrophenols.