Unraveling discriminative-hydrogen-activation over Cu-based catalysts for boosting nitroarenes hydrogenation: Crystal effect and mechanism insight

Abstract

Copper is a crucial element in the field of catalysis. However, Cu-based catalysts exhibit lower redox properties and surface energy under mild conditions, which limit their electron transfer capacities and catalytic performance. In this study, the relationship investigation between the hydrogenation behavior of Cu-based catalysts and crystal phases showed that spherical Cu2O exhibited enhanced capacity for hydrogen activation, excellent catalytic activity and outstanding reusability in the selective reduction of various nitroarenes. At even 25 °C and 1 atm, the complete reduction of 4-nitrophenol by NaBH4 was achieved in 2.5 min over Cu2O, achieving a reaction rate constant (k) of 20.15 × 10−3 s−1, which was 4.8 and 15.2 times that of CuO and Cu catalysts. Detailed experimental and theoretical calculations revealed that the Cu+ sites in the antifluorite crystal phase of Cu2O are conducive to the adsorption of active H species, while the unique d–s orbital recombination provides more electrons to improve its hydrogenation performance. The results of this study can aid in the development of copper-based materials as advanced catalysts, thereby improving fine chemical production and pollution treatment processes.