Preparation of nanocellulose/reduced graphene oxide matrix loaded with cuprous oxide nanoparticles for efficient catalytic reduction of 4-nitrophenol

The paper reports on the preparation of cellulose nanocrystals/reduced graphene oxide matrix loaded with cuprous oxide nanoparticles (CNC/rGO-Cu₂O) through a simple solvothermal method and its application for 4-nitrophenol reduction to 4-aminophenol using sodium borohydride. The CNC/rGO-Cu₂O nanocomposite was formed chemically by first mixing CNC and graphene oxide (GO) followed by complexation of the negatively charged functional groups of CNC/GO with Cu²⁺ ions and subsequent heating at 100°C. This resulted in the simultaneous reduction of GO to rGO and the formation of Cu₂O nanoparticles. The as-elaborated nanocomposite was firstly characterized using different techniques such as atomic force microscopy, scanning electron microscopy, transmission electron microscopy, UV–Vis spectrophotometry, Raman spectroscopy and x-ray photoelectron spectroscopy. Then, it was successfully applied for efficient catalytic reduction of 4-nitrophenol to 4-aminophenol using sodium borohydride: the reduction was completed in about 6 min. After eight times use, the catalyst still maintained good catalytic performance. Compared to CNC/rGO, rGO/Cu₂O and free Cu₂O nanoparticles, the CNC/rGO-Cu₂O nanocomposite exhibits higher catalytic activity even at lower copper loading.