Codeposition of Palladium and Gold on Nickel Wire Electrodes via Galvanic Replacement Reactions for Ethanol Oxidation

Codeposition of Pd and Au on a Ni wire was explored using a simple treatment of Ni wire electrodes in aqueous solutions containing both K2PdCl4 and HAuCl4, and the electrochemical properties of the thus-prepared electrodes were evaluated by recording cyclic voltammograms (CVs) of 1.0 M ethanol in 1.0 M NaOH aqueous solutions. Compared with the Pd-deposited Ni wire electrodes prepared by treatment in aqueous solutions of K2PdCl4, a remarkable increase in the electrocatalytic current of ethanol oxidation was observed when both the concentrations of K2PdCl4 and HAuCl4 were as low as 0.10 mM and after the treatment for 10 min at 30 degrees C. The results of the EDS elemental mapping analysis show that the distributions of Pd and Au on the Ni surface were not identical and that Au deposited preferentially on Ni. By observing the changes in the CV responses depending on the concentrations of K2PdCl4 and HAuCl4 and performing stepwise modifications, the promotion or acceleration of the codeposition of PdAu was found to be achieved due to the coexistence of K2PdCl4 and HAuCl4 in aqueous solutions. Because the codeposition of PdAu revealed in the present work was significant, it was found that PdAu-modified or PdAu-coated Ni materials could be prepared via simple galvanic replacement reactions without using any reducing reagents and additives.

使用在含四氯钯酸钾（K₂PdCl₄）和四氯金酸（HAuCl₄）的水溶液中对镍丝电极进行简单处理的方法，探索了钯（Pd）和金（Au）在镍丝上的共沉积。通过记录1.0 M乙醇在1.0 M氢氧化钠水溶液中的循环伏安图（CV），对如此制备的电极的电化学性能进行了评估。与在四氯钯酸钾水溶液中处理制备的沉积钯的镍丝电极相比，当四氯钯酸钾和四氯金酸的浓度都低至0.10 mM，并在30℃下处理10分钟时，观察到乙醇氧化的电催化电流显著增加。能谱仪（EDS）元素映射分析结果表明，钯和金在镍表面的分布并不相同，金优先沉积在镍上。通过观察循环伏安响应随四氯钯酸钾和四氯金酸浓度的变化以及进行逐步修饰，发现由于水溶液中四氯钯酸钾和四氯金酸的共存，实现了钯金共沉积的促进或加速。由于本研究中揭示的钯金共沉积现象显著，发现可以通过简单的电置换反应制备钯金修饰或钯金包覆的镍材料，而无需使用任何还原剂和添加剂。