Oxygen reduction at platinum- and gold-coated copper deposits on glassy carbon substrates

Oxygen reduction has been studied on glassy carbon rotating disc substrates modified by platinum- and gold-coated copper particles. The deposits have been formed by a two-step process, whereby controlled amounts of Cu were electrodeposited onto the substrate and were subsequently coated with a thin Pt or Au layer upon immersion of the Cu/GC electrode into chloroplatinic or chlorolauric acid solutions. The spontaneous surface replacement of Cu by Pt or Au resulted in Pt(Cu)/GC or Au(Cu)/GC electrodes which consisted of dispersed Pt(Cu) or Au(Cu) particles and displayed typical Pt and Au surface electrochemistry. Based on mass transfer-corrected Tafel plots, the oxygen reduction catalytic activity in acid of platinum- and gold-coated copper deposits has been compared to that of bulk Pt and Au respectively.