Abstract
The electrocatalytic oxygen reduction reaction (ORR) at copper nanopartides (nano-Cu) modified Au(100)-rich polycrystalline gold electrode (nano-Cu/Au-r) in 0.5 M KOH is studied using cyclic and rotating disk voltammetry. The nano-Cu/Au-r with a relatively enriched free Au(100) facet compared with the bare poly-Au electrode is prepared by a controlled electrodeposition of nano-Cu only on the Au(111) facet of the poly-Au electrode the other low-index facets (i.e., Au(100) and Au(110)) of which are previously covered with the self-assembled monolayer of cysteine. The electrocatalytic behavior of the nano-Cu/Au-r is compared with those of the bare Au and the copper nanopartides-modified gold electrodes (nano-Cu/Au) in which the nano-Cu is directly electrodeposited onto the poly-Au electrode. The nano-Cu/Au-r shows a remarkable electrocatalysis, comparable to that of the platinum electrode, toward the ORR i.e., the ORR proceeds exclusively via a 1-step 4-electron reduction pathway at ca. 20-65 mV more positive potentials than at the bare Pt electrode, while the ORR at the nano-Cu/Au proceeds via a two-electron pathway. X-ray diffraction spectra confirms the relative enrichment of nano-Cu/Au-r electrode in Au(100) facet. The relative enrichment in the free Au(100) facet of the nano-Cu/Au-r electrode is thought to be behind the extraordinary electrocatalytic activity. (C) 2012 Elsevier B.V. All rights reserved.