Copper Nanoparticles-Decorated Carbon Nanoflakes as a Catalyst for Nitroaromatic Reduction

Herein, we have developed highly active copper nanoparticles (CuNPs)-decorated carbon nanoflakes (CNFs) as a catalyst for the efficient reduction of nitroaromatic compounds, including para-nitrophenol (PNP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP), to their respective amines at room temperature in the presence of sodium borohydride (NaBH4) in water. It is observed that the percentage of reduction of PNP is ∼100%, and more interestingly, the catalyst reduces even DNP and TNP with an excellent conversion yield of ∼95 and ∼94%, respectively, within 15 min. The reduction reaction of nitroaromatic compounds follows pseudo-first-order kinetics with rate constants of 0.2962, 0.19893, and 0.20866 min–1 for PNP, DNP, and TNP, respectively. UV–vis absorption and FT-IR spectra confirm the conversion of nitroaromatic derivatives to their corresponding amine derivatives. Finally, we also established the plausible reaction mechanism for the reduction process by carrying out various control experiments. In brief, the reduction of nitrophenol occurs via the adsorption of activated hydrogen and nitrophenolate ions followed by reduction through electron transfer and by taking active H from the surface of Cu-CNFs.