Xie Yunxiang, Dimitrov Nikolay
Department of Chemistry, Binghamton University-SUNY, Binghamton, New York 13902, United States.
ACS Omega. 2018 Dec 18;3(12):17676-17686. doi: 10.1021/acsomega.8b02148. eCollection 2018 Dec 31.
Cu Au bimetallic ultrathin-film catalysts for nitrate electroreduction have been synthesized using electrochemical atomic layer deposition by surface-limited redox replacement of Pb underpotentially deposited layer. Controlled by the ratio of [Cu] ions and [AuCl ] complex in the deposition solution, the alloy film composition (atomic fraction, in the range of 0.5-1) has been determined by X-ray photoelectron spectroscopy and indirectly estimated by anodic stripping voltammetry. The catalytic activity and durability of Cu Au thin films, Cu thin film, and bulk Cu have been studied by one- and multiple-cycle voltammetry. The synthesized Cu Au thin films feature up to two times higher nitrate electroreduction activity in acidic solution compared to bulk and thin-film Cu counterparts. Highest activity has been measured with a CuAu catalyst. Durability tests have demonstrated that Cu thin films undergo rapid deactivation losing 65% of its peak activity for 92 cycles, whereas CuAu catalysts lose only 45% of their top performance. The significantly better durability of alloy films can be attributed to effective resistance to poisoning and/or hindered dissolution of Cu active centers. It has been also found that both Cu Au and pure Cu thin films show best electroreduction activity at lowest pH.
通过在欠电位沉积的Pb层表面进行受限氧化还原置换的电化学原子层沉积法，合成了用于硝酸盐电还原的CuAu双金属超薄膜催化剂。通过沉积溶液中[Cu]离子与[AuCl]络合物的比例控制，利用X射线光电子能谱确定了合金膜的组成（原子分数，范围为0.5 - 1），并通过阳极溶出伏安法进行了间接估算。通过单循环和多循环伏安法研究了CuAu薄膜、Cu薄膜和块状Cu的催化活性和耐久性。合成的CuAu薄膜在酸性溶液中的硝酸盐电还原活性比块状和薄膜状Cu高出两倍。使用CuAu催化剂测得的活性最高。耐久性测试表明，Cu薄膜在92个循环后迅速失活，其峰值活性损失65%，而CuAu催化剂仅损失其最高性能的45%。合金膜显著更好的耐久性可归因于对中毒的有效抗性和/或Cu活性中心溶解的受阻。还发现，CuAu和纯Cu薄膜在最低pH值下均表现出最佳的电还原活性。
