Preparation of nitrogen-doped Cu-biochar and its application into catalytic reduction of p-nitrophenol

Nitrogen-doped copper-biochar (N-Cu-biochar) was synthesized via pyrolysis of glucose in the presence of copper and melamine and used as a catalyst in the reduction of p-nitrophenol by NaBH₄. N-Cu-biochar was characterized by field emission scanning electron microscopy/energy-dispersive spectroscopy, Raman spectroscopy, X-ray Diffraction, and Brunauer-Emmett-Teller surface analyzer. The catalytic performance of N-Cu-biochar was evaluated under varying conditions of NaBH₄ concentration, biochar dosage, and initial p-nitrophenol concentration. N-Cu-biochar was composed of ~83% C, ~9% O, and ~8% Cu, with Cu/Cu₂O phases evenly dispersed on graphitic carbon aggregates possessing both macro- and meso-pores. N-Cu-biochar showed superior catalytic ability in mediating p-nitrophenol reduction as compared to Cu-biochar and N-doped biochar, achieving complete reduction of 0.35 mM p-nitrophenol within 30 min at a dose of 0.25 g L^-1. Reduction of p-nitrophenol catalyzed by N-Cu-biochar followed pseudo-first-order kinetics, and the reaction rate was dependent upon NaBH₄ concentration. The overall results indicate that biochar can be a suitable candidate as a support for catalyst synthesis, and N-doped Cu-biochar can be a promising catalyst for the reduction of p-nitrophenol.