Li Yongxian, Chen Jia-Yi, Zhang Xinchao, Peng Zhiqiang, Miao Qiyi, Chen Wang, Xie Fei, Liao Rong-Zhen, Ye Shengfa, Tung Chen-Ho, Wang Wenguang
College of Chemistry, Beijing Normal University, Beijing 100875, China.
School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
J Am Chem Soc. 2023 Dec 13;145(49):26915-26924. doi: 10.1021/jacs.3c09824. Epub 2023 Nov 29.
Exploring bidirectional CO/HCO catalysis holds significant potential in constructing integrated (photo)electrochemical formate fuel cells for energy storage and applications. Herein, we report selective CO/HCO electrochemical interconversion by exploiting the flexible coordination modes and rich redox properties of a versatile iron-thiolate platform, Cp*Fe(II)L (L = 1,2-PhPCHS). Upon oxidation, this iron complex undergoes formate binding to generate a diferric formate complex, [(L)Fe(III)(μ-HCO)Fe(III)], which exhibits remarkable electrocatalytic performance for the HCO-to-CO transformation with a maximum turnover frequency (TOF) ∼10 s and a Faraday efficiency (FE) ∼92(±4)%. Conversely, this iron system also allows for reduction at -1.85 V (vs Fc) and exhibits an impressive FE ∼93 (±3)% for the CO-to-HCO conversion. Mechanism studies revealed that the HCO-to-CO electrocatalysis passes through dicationic [(L)Fe(III)(μ-HCO)Fe(III)] generated by unconventional oxidation of the diferric formate species taking place at ligand L, while the CO-to-HCO reduction involves a critical intermediate of [Fe(II)-H] that was independently synthesized and structurally characterized.
探索双向CO/HCO催化在构建用于能量存储和应用的集成（光）电化学甲酸盐燃料电池方面具有巨大潜力。在此，我们报道了通过利用通用的铁硫醇盐平台Cp*Fe(II)L（L = 1,2-PhPCHS）的灵活配位模式和丰富的氧化还原性质实现选择性CO/HCO电化学相互转化。氧化时，该铁配合物与甲酸盐结合生成双铁甲酸盐配合物[(L)Fe(III)(μ-HCO)Fe(III)]，其对HCO到CO的转化表现出卓越的电催化性能，最大周转频率（TOF）约为10 s⁻¹，法拉第效率（FE）约为92(±4)%。相反，该铁体系在 -1.85 V（相对于Fc）时也能进行还原反应，并且对于CO到HCO的转化表现出令人印象深刻的FE约为93 (±3)%。机理研究表明，HCO到CO的电催化过程通过配体L处双铁甲酸盐物种的非常规氧化生成的二价阳离子[(L)Fe(III)(μ-HCO)Fe(III)]进行，而CO到HCO的还原涉及独立合成并进行结构表征的关键中间体[Fe(II)-H]。
