Studies of Cobalt-Mediated Electrocatalytic CO2 Reduction Using a Redox-Active Ligand

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• 作者：David C. Lacy ; Charles C. L. McCrory ; Jonas C. Peters
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 19, 2014
• 年：2014
• 卷：53
• 期：10
• 页码：4980-4988
• 全文大小：379K
• 年卷期：v.53,no.10(May 19, 2014)
• ISSN：1520-510X

文摘

The cobalt complex [Co^IIIN₄H(Br)₂]⁺ (N₄H = 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]-heptadeca-1(7),2,11,13,15-pentaene) was used for electrocatalytic CO₂ reduction in wet MeCN with a glassy carbon working electrode. When water was employed as the proton source (10 M in MeCN), CO was produced (f_CO= 45% 卤 6.4) near the Co^I/0 redox couple for [Co^IIIN₄H(Br)₂]⁺ (E_1/2 = 鈭?.88 V FeCp₂^+/0) with simultaneous H₂ evolution (f_H2= 30% 卤 7.8). Moreover, we successfully demonstrated that the catalytically active species is homogeneous through the use of control experiments and XPS studies of the working glassy-carbon electrodes. As determined by cyclic voltammetry, CO₂ catalysis occurred near the formal Co^I/0redox couple, and attempts were made to isolate the triply reduced compound (鈥淸Co⁰N₄H]鈥?. Instead, the doubly reduced (鈥淐o^I鈥? compounds [CoN₄] and [CoN₄H(MeCN)]⁺ were isolated and characterized by X-ray crystallography. Their molecular structures prompted DFT studies to illuminate details regarding their electronic structure. The results indicate that reducing equivalents are stored on the ligand, implicating redox noninnocence in the ligands for H₂ evolution and CO₂ reduction electrocatalysis.