Abstract
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•A novel Cu-based catalyst Cu/CuxO@CN was prepared by a facile method.•Cu/CuxO@CN exhibits extremely high catalytic activity in 4-nitrophenol reduction.•A rate constant as high as 0.126 s−1 was observed on Cu/CuxO@CN.•Metallic Cu NPs are demonstrated to be the active sites in 4-nitrophenol reduction.•The superior catalytic activity mainly stems from N doping in carbon matrix.
Developing low-cost non-precious metals as efficient catalysts for the reduction of toxic 4-nitrophenol (4-NP) to useful 4-aminophenol (4-AP) have received increasing attention in recent years. Herein, a novel and efficient Cu-based catalyst Cu/CuxO@CN (carbon doped with nitrogen) was prepared via a facile method from pyrolysis of bi-ligand MOFs material Cu2(BDC)2(BPY) (BDC = p-Phthalic acid, BPY = 4,4′-bipyridyl) in Ar atmosphere. Characterization results revealed that N doping in carbon matrix favors the development of mesoporous structure, the formation of more defect sites in carbon matrix, better dispersion of Cu/CuxO nano particles, and maintenance of Cu species in metallic Cu state (the active site), all of which contribute to a superior catalytic activity for 4-NP reduction with a pseudo-first-order rate constant as high as 0.126 s−1 (the molar ratio of NaBH4 to 4-NP is 400), nearly 11 times higher than its counterpart Cu/CuxO@C without N doping (0.011 s−1). The activation energy for 4-NP reduction to 4-AP catalyzed by Cu/CuxO@CN was determined as 55.6 kJ mol−1 (the molar ratio of NaBH4 to 4-NP is 100). In addition, Cu/CuxO@CN showed excellent reusability in successive 6 cycles. The facile synthesis and superior catalytic activity make Cu/CuxO@CN a promising catalyst in industrial applications for many other similar reaction systems.