Ultrafast Growth of a Cu(OH)<sub>2</sub>–CuO Nanoneedle Array on Cu Foil for Methanol Oxidation Electrocatalysis
Sengeni Anantharaj, Hisashi Sugime, Suguru Noda
Abstract
A swift potentiostatic anodization method for growing a 5–7 μm tall nanoneedle array of Cu(OH)2–CuO on Cu foil within 100 s has been developed. This catalytic electrode when screened for methanol oxidation electrocatalysis in 1 M KOH with 0.5 M methanol, delivered a current density as high as 70 ± 10 mA cm–2 at 0.65 V versus Hg/HgO which is superior to the performance of many related catalysts reported earlier. The observed activity enhancement is attributed to the formation of both Cu(OH)2–CuO nanoneedle arrays of high active surface area over the metallic Cu foil. In addition, the Cu(OH)2–CuO/Cu electrode had also exhibited excellent stability upon prolonged potentiostatic electrocatalytic oxidation of methanol while retaining the charge-transfer characteristics. Growth of such highly ordered assembly of Cu(OH)2–CuO nanoneedles within a minute has never been achieved before. When compared to its oxygen evolution reaction activity, the addition of 0.5 M methanol has lowered the overpotential at 10 mA cm–2 by 334 mV, which is significant. This encourages the use of methanol as a sacrificial anolyte for energy-saving production of H2 from water electrolysis.