Preparation of Gold Modified Nickel Wire Electrodes for Electroanalysis via a Galvanic Replacement Reaction

Gold modified nickel (Ni) electrodes were prepared via a simple galvanic replacement reaction between chloroauric acid (AuCl4-) and Ni base materials. Au nano- or micro-structures were deposited on the Ni surface by immersing Ni disk/wire electrode in an aqueous solution of AuCl4-. The concentration of AuCl4- and the immersion time were systematically varied, and the surfaces of Ni wire were characterized by scanning electron microscopy (SEM). Furthermore, electrochemical responses of ferrocyanide, uric acid and glucose were observed with Au modified Ni wire electrodes prepared at lower concentrations of AuCl4- (below 1.0x10(-4) M) after fixing some conditions. Consequently, reversible electrochemical responses of ferrocyanide could be observed even for Ni wire treated with 1.0x10(-6)M AuCl4-, though no deposition was observed in the SEM measurements. Also, control of electrocatalytic activity was possible below 1.0x10(-4)M AuCl4- for uric acid and glucose. Judging from the tunable electrocatalytic performance, simplicity of preparation, and the cost of electrode materials, we believe that Au modified Ni electrodes holds promise for applications in electroanalysis. On the other hand, in our preliminary trials, the properties of deposited Au nano- or micro-particles were found to be sensitive to several factors. Further work is needed to achieve quantitative Au deposition over individual electrodes.