Md Ahsan Habib, Breedlove Brian K, Cosquer Goulven, Yamashita Masahiro
Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aza-Aoba, Aramaki, Sendai, 980-8578, Japan.
Chemistry Discipline, Science, Engineering and Technology School, Khulna University, Khulna-9208, Bangladesh.
Dalton Trans. 2021 Oct 5;50(38):13368-13373. doi: 10.1039/d1dt02318g.
Tethering metal complexes, like [Ru(bpy)Cl] (bpy = 2,2'-bipyridine), which are redox-active at low reduction potentials and have the ability to transfer electrons to another complex, to a [Ni(cyclen)] electrocatalyst enhanced the reduction of CO to CO at low overpotentials. The [Ni(cyclen)] electrocatalyst was modified by tethering redox-active metal complexes 4-methylpyridyl linkers. The redox-active metal complexes were reduced after CO bound to the active site. In controlled potential electrolysis (CPE) experiments in 95 : 5 (v/v) CHCN/HO, [{([Ru]pic)cyclen}NiCl] ([Ru] = {Ru(bpy)Cl}; pic = 4-methylpyridyl) could be used to reduce CO into CO at a turnover frequency (TOF) of 708 s with a faradaic efficiency (FE) of 80% at an onset potential of -1.60 V . NHE. At the same time, this electrocatalyst was active at an onset potential of -1.25 V . NHE, which is the reduction potential of one of the bpy ligands of the [Ru] moieties, with FE = 84% and TOF = 178 s. When the electrocatalysis was performed using [bncyclenNiCl]Cl (bn = benzyl) without tethered redox-active metal complexes, the TOF value was determined to be 8 s with FE = 77% at an onset potential of -1.45 V . NHE. The results show that tethering redox-active metal complexes significantly improves the electrocatalytic activities by lowering the potential needed to reduce CO.
将诸如[Ru(bpy)Cl]（bpy = 2,2'-联吡啶）之类的金属配合物连接到[Ni(环烯)]电催化剂上，这些金属配合物在低还原电位下具有氧化还原活性，并且能够将电子转移到另一种配合物上，从而在低过电位下增强了将CO还原为CO的能力。通过连接氧化还原活性金属配合物4-甲基吡啶基连接体对[Ni(环烯)]电催化剂进行了修饰。在CO与活性位点结合后，氧化还原活性金属配合物被还原。在95∶5（v/v）的CHCN/H₂O的控制电位电解（CPE）实验中，[{([Ru]pic)环烯}NiCl]（[Ru] = {Ru(bpy)Cl}；pic = 4-甲基吡啶基）可用于在起始电位为 -1.60 V（相对于标准氢电极，NHE）时，以708 s⁻¹的周转频率（TOF）和80%的法拉第效率（FE）将CO还原为CO。同时，这种电催化剂在起始电位为 -1.25 V（相对于NHE）时具有活性，该电位是[Ru]部分的一个bpy配体的还原电位，FE = 84%，TOF = 178 s⁻¹。当使用没有连接氧化还原活性金属配合物的[bn环烯NiCl]Cl（bn = 苄基）进行电催化时，在起始电位为 -1.45 V（相对于NHE）时，TOF值确定为8 s⁻¹，FE = 77%。结果表明，连接氧化还原活性金属配合物通过降低还原CO所需的电位，显著提高了电催化活性。
