Cobalt porphyrin catalyzed reduction of CO2.: Radiation chemical, photochemical, and electrochemical studies
Cobalt porphyrin catalyzed reduction of CO2.: Radiation chemical, photochemical, and electrochemical studies
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DOI：
10.1021/jp9807017
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发表时间：
1998-04-23
影响因子：
2.9
通讯作者：
Fujita, E
中科院分区：
文献类型：
--
作者：
Behar, D;Dhanasekaran, T;Fujita, E
几种钴卟啉（CoP）已被还原的辐射化学，光化学和电化学方法，在水溶液和有机溶剂。在水溶液中，（CoP）-P-1状态在高pH下稳定，但在中性和酸性溶液中寿命较短。在有机溶剂中也观察到稳定的（CoP）-P-1，并且对CO2不反应。（CoP）-P-1的单电子还原导致形成一种物质，该物质在水溶液中通过脉冲辐解被观察为瞬态中间体，并且在四氢呋喃溶液中通过Na还原后被观察为稳定产物。该物种的光谱不是金属卟啉π自由基阴离子的特征光谱，并且归因于（CoP）-P-0。该物种结合并减少二氧化碳。在含有三乙胺作为还原猝灭剂的乙腈溶液中，通过光化学实验证实了CO和HCO 2-的催化形成。在乙腈和丁腈溶液中的循环伏安法也证实了CO2的催化还原，并且显示在（CoP）-P-1还原为（CoP）-P-0的电位下发生。与CoTPP相比，氟化衍生物在较小的负电位下被还原，并催化CO2还原。
Several cobalt porphyrins (CoP) have been reduced by radiation chemical, photochemical, and electrochemical methods, in aqueous and organic solvents. In aqueous solutions, the (CoP)-P-1 state is stable at high pH but is shorter lived in neutral and acidic solutions. Stable (CoP)-P-1 is also observed in organic solvents and is unreactive toward CO2. One-electron reduction of (CoP)-P-1 leads to formation of a species that is observed as a transient intermediate by pulse radiolysis in aqueous solutions and as a stable product following reduction by Na in tetrahydrofuran solutions. The spectrum of this species is not the characteristic spectrum of a metalloporphyrin pi-radical anion and is ascribed to (CoP)-P-0. This species binds and reduces CO2. Catalytic formation of CO and HCO2- is confirmed by photochemical experiments in acetonitrile solutions containing triethylamine as a reductive quencher. Catalytic reduction of CO2 is also confirmed by cyclic voltammetry in acetonitrile and butyronitrile solutions and is shown to occur at the potential at which (CoP)-P-1 is reduced to (CoP)-P-0. As compared with CoTPP, fluorinated derivatives are reduced, and catalyze CO2 reduction, at less negative potentials.