Surface oxidation of copper-based e-waste for the formation of copper oxide nanowires and their photocatalytic properties

Abstract

A large volume of waste electric cables, originating from obsolete electronic and electrical equipment, contributes significantly to the growing burden of electronic waste and poses considerable environmental risks. In this study, cupric oxide nanowires were synthesized via thermal oxidation of waste electric cables and compared with those produced from commercial copper sheets. Unlike previous studies that typically use high-purity copper sources and extended oxidation times, this work demonstrates the direct conversion of e-waste into functional CuO nanowires at reduced temperatures and significantly shorter processing durations, offering a more sustainable and energy-efficient synthesis route. The photocatalytic activity of the nanowires was then evaluated through the reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). Rapid Cr(VI) reduction was observed for CuO nanowires formed at 500 °C, attributed to the higher nanowires’ density at this temperature. Notably, CuO nanowires formed with oxidation times below 10 min demonstrated good photocatalytic performance, supporting the objective of this study to produce efficient nanowires under significantly reduced oxidation temperatures and durations.