Wood Fibre-Supported Cu, Co and Fe Nanoparticles for Sustainable Catalytic Hydrogenation

Bio-derived functional materials are key platforms for long-term sustainable environmental remediation. Pine wood fibres (WF) are an abundant and renewable material with functional properties suited to specialized applications, including high density of hydroxyl groups at its surface and mechanical toughness imparted by the lignin fraction. In the present work, monometallic and bimetallic nanoparticles (MNP) of first-series transition metals, Fe, Co, Cu and Fe/Cu were immobilized onto original WF and WF treated with NaOH (WF_N). The prepared WF-supported MNP were characterized by SEM/EDS, XPS, XRD and FTIR-ATR, and evaluated in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in aqueous solution, at room temperature, by NaBH4. Copper-based materials exhibited superior catalytic efficiency, with the NaOH pre-treatment of the fibres yielding shorter induction times and enhanced stability. For the WF_NCu material, 97% of 4-NP reduction was achieved in 3 min with a rate constant of k1 = 2.147 min−1. This material was used for five successive cycles with no decrease in 4-NP reduction efficiency, being easily recovered from the reaction media.