Repurposed Cu Scrap Featuring CuO/Cu(OH)2 Nanostructures as a High-Performance Anode for OER-Masking Small Molecule Electrooxidation

An efficient and eco-friendly way of recovering and repurposing Cu scrap wires from e-waste has been developed. This involves a simple precleaning followed by a potential-controlled anodization, populating the surface of the recovered Cu scrap wires with dense Cu(OH)₂/CuO nanoneedles. The resultant electrodes were used as an electrocatalytic interface for the oxidation reactions of urea (UOR), methanol (MOR), and glucose (GOR) and compared with their oxygen evolution reaction (OER) performance. Our results show that the moderately OER-active Cu(OH)₂/CuO nanoneedle arrays are efficient in UOR, MOR, and GOR in 1.0 M KOH. The potentials required by this electrode to drive a current density of 10 mA cm^–2 in UOR, MOR, and GOR are 1.499, 1.438, and 1.192 V vs RHE, respectively. When the OER masking ability of Cu(OH)₂/CuO nanoneedle featuring Cu scrap wires was tested, it was found that this catalytic anode required 157 mV (with UOR), 218 mV (with MOR), and 464 mV (with GOR) less than what is needed for OER to deliver 10 mA cm^–2 in 1.0 M KOH. These encouraging findings open new avenues for bettering and improving the recovery, repurposing, and reuse of 9 million metric tons of Cu scraps generated annually.