Highly active Cu-embedded in magnetic carbon nanofibers for the reduction of 4-nitrophenol

This study introduces a novel approach for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using Cu embedded in magnetic carbon nanofibers (CNFs) derived from CO₂ hydrogenation. The synthesis involves CO₂ hydrogenation over a Ni-Na/Al₂O₃ catalyst to produce CNFs, which support Cu atoms without requiring an external reductant. Low Cu loadings (0.25–1.0 wt%) effectively aggregate at the atomic level, enhancing catalytic activity through interactions with oxygen-containing groups (–COOH and –OH) on CNFs. Characterization of the Cu embedded in CNFs (Cu_x/CNFs) showed that despite a slight reduction in surface area with increased Cu loading, the materials maintained robust catalytic properties and magnetic characteristics, aiding in the easy post-reaction separation from aqueous solutions. Catalytic tests demonstrated that Cu_x/CNFs surpass the efficiency of traditional noble metal catalysts, following pseudo-first-order kinetics. The character of positive charge of Cu atoms could significantly enhance the adsorption efficiency of 4-NP molecules on Cu_x/CNFs including adsorption amount and adsorption rate.