Green synthesis of Cu nanoparticles supported on straw-graphene composite for catalytic reduction of p-nitrophenol

Abstract It is quite desired to develop an effective and cost-efficient non-noble metal catalyst for the reduction of nitrobenzene compounds. In this work, a novel and highly reactive Cu nanoparticles (CuNPs) embedded straw-graphene composite (Cu-SG) was synthesized via a facile and green one-pot hydrothermal route and then used for p-nitrophenol (PNP) reduction in the presence of NaBH4 from an aqueous medium. In comparison to the Cu-G (0.42 min-1), the Cu-SG with hierarchical pore structure and smaller CuNPs exhibited better catalytic property in PNP reduction, especially under the condition of a mass ratio of straw-to-GO = 1 and Cu2+ ions dosage = 0.15 mmol (0.93 min-1). Interestingly, unlike Cl-, NO3- and SO42- ions, the coexisted HCO3- ions in solution could crucially accelerate the removal of PNP (1.62 min-1). This may be since HCO3- ions can both ionize and hydrolyze in water, enabling them to regulate and promote the adsorption of PNP to Cu-SG. Besides, the Cu-SG displayed good catalytic stability and can be reused for six consecutive cycles without obvious performance reduction. This study offers insights into addressing both water pollution remediation and agricultural solid waste reuse.