Department of Materials Science and Engineering, and ‡Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH) , Pohang 790-784, Korea.
ACS Appl Mater Interfaces. 2017 Dec 20;9(50):43575-43582. doi: 10.1021/acsami.7b10308. Epub 2017 Dec 8.
Nanostructured metal catalysts to convert CO to formate, which have been extensively studied over decades, have many problems such as durability, lifetime, high process temperature, and difficulty in controlling the morphology of nanostructures. Here, we report a facile method to fabricate monolithic nanoporous In-Sn alloy, a network of nanopores, induced by electroreduction of indium tin oxide nanobranches (ITO BRs). The electroreduction process concentrated a local electric field at the tip of the nanostructure, leading to current-assisted joule-heating to form a nanoporous In-Sn alloy. Scanning electron microscopy images showed that the nanopore size of In-Sn alloy could be controlled from 1176 to 65 nm by tuning the electroreduction condition: the applied potential and the time. As a result, formate Faradaic efficiency could be improved from 42.4% to 78.6%. Also, current density was increased from -6.6 to -9.6 mA/cm at -1.2 V, thereby resulting in the highest HCOO production rate of 75.9 μmol/(h cm). Detachment of catalysts from the substrate was not observed even after a long-term (12 h) electrochemical measurement at high potential (-1.2 V). This work provides a design rule to fabricate highly efficient and stable oxide-derived electrocatalysts.
几十年来，人们广泛研究了将 CO 转化为甲酸盐的纳米结构金属催化剂，但这种催化剂存在许多问题，如耐久性、使用寿命、高工艺温度以及纳米结构形态控制困难等。在这里，我们报告了一种简便的方法来制备整体式纳米多孔 In-Sn 合金，这是一种由氧化铟锡纳米枝晶（ITO BRs）电还原诱导的纳米孔网络。电还原过程在纳米结构的尖端集中局部电场，导致电流辅助焦耳加热形成纳米多孔 In-Sn 合金。扫描电子显微镜图像显示，通过调整电还原条件（施加的电势和时间），可以将 In-Sn 合金的纳米孔尺寸从 1176nm 控制到 65nm。结果，甲酸盐法拉第效率从 42.4%提高到 78.6%。此外，在-1.2V 的高电势下进行长时间（12 小时）电化学测量时，电流密度从-6.6mA/cm 增加到-9.6mA/cm，从而产生了最高的 HCOO 生成速率为 75.9μmol/（h·cm）。即使在高电势（-1.2V）下进行长时间的电化学测量，催化剂也没有从基底上脱落。这项工作为制备高效稳定的氧化物衍生电催化剂提供了设计规则。
