Electrokinetic-mechanism of water and furfural oxidation on pulsed laser-interlaced Cu2O and CoO on nickel foam

Abstract

The electrocatalytic oxidation of biomass-derived furfural (FF) feedstocks into 2-furoic acid (FA) holds immense industrial potential in optics, cosmetics, polymers, and food. Herein, we fabricated CoO/NiO/nickel foam (NF) and Cu2O/NiO/NF electrodes via in situ pulsed laser irradiation in liquids (PLIL) for the bifunctional electrocatalysis of oxygen evolution reaction (OER) and furfural oxidation reaction (FOR), respectively. Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu2O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR. CoO/NiO/NF electrocatalyst provides a consistently low overpotential of ∼359 mV (OER) at 10 mA/cm2, achieving the maximum FA yield (∼16.37 mM) with 61.5% selectivity, 79.5% carbon balance, and a remarkable Faradaic efficiency of ∼90.1% during 2 h of FOR at 1.43 V (vs. reversible hydrogen electrode). Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates (NiOOH and CoOOH) as surface-active centers during electrochemical oxidation. The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products. This method holds promise for large-scale applications, enabling simultaneous production of renewable building materials and fuel.