Han Sang Myeong, Park Minyoung, Kim Jiyoung, Lee Dongil
Department of Chemistry, Yonsei University, Seoul, 03722, Republic of Korea.
Angew Chem Int Ed Engl. 2024 Jul 29;63(31):e202404387. doi: 10.1002/anie.202404387. Epub 2024 Jun 25.
The electrochemical CO reduction reaction (CORR) has been widely studied as a promising means to convert anthropogenic CO into valuable chemicals and fuels. In this process, the alkali metal ions present in the electrolyte are known to significantly influence the CORR activity and selectivity. In this study, we report a strategy for preparing efficient electrocatalysts by introducing a cation-relaying ligand, namely 6-mercaptohexanoic acid (MHA), into atom-precise Au nanoclusters (NCs). The CORR activity of the synthesized Au(MHA) NCs was compared with that of Au(HT) NCs (HT=1-hexanethiolate). While both NCs selectively produced CO over H, the CO-to-CO conversion activity of the Au(MHA) NCs was significantly higher than that of the Au(HT) NCs when the catholyte pH was higher than the pK of MHA, demonstrating the cation-relaying effect of the anionic terminal group. Mechanistic investigations into the CORR occurring on the Au NCs in the presence of different catholyte cations and concentrations revealed that the CO-to-CO conversion activities of these Au NCs increased in the order Li<Na<K<Cs, and are gated by the cation-coupled electron transfer step. These results were confirmed by the Nernstian shifts of the polarization curves at different cation concentrations.
电化学CO还原反应（CORR）作为一种将人为产生的CO转化为有价值的化学品和燃料的有前景的方法，已得到广泛研究。在这个过程中，已知电解质中存在的碱金属离子会显著影响CORR活性和选择性。在本研究中，我们报告了一种通过将阳离子中继配体，即6-巯基己酸（MHA），引入原子精确的金纳米团簇（NCs）中来制备高效电催化剂的策略。将合成的Au（MHA）NCs的CORR活性与Au（HT）NCs（HT = 1-己硫醇盐）的CORR活性进行了比较。虽然两种NCs在H之上都选择性地产生CO，但当阴极电解液pH高于MHA的pK时，Au（MHA）NCs的CO-to-CO转化活性显著高于Au（HT）NCs，这证明了阴离子端基的阳离子中继效应。对在不同阴极电解液阳离子和浓度存在下Au NCs上发生的CORR的机理研究表明，这些Au NCs的CO-to-CO转化活性按Li<Na<K<Cs的顺序增加，并且受阳离子耦合电子转移步骤的控制。这些结果通过不同阳离子浓度下极化曲线的能斯特位移得到了证实。
