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Molecular Electrochemical Catalysis of the CO2-to-CO Conversion with a Co Complex: A Cyclic Voltammetry Mechanistic Investigation
Organometallics ( IF 2.5 ) Pub Date : 2018-09-18 , DOI: 10.1021/acs.organomet.8b00555 Claudio Cometto 1 , Lingjing Chen 2 , Elodie Anxolabéhère-Mallart 1 , Claire Fave 1 , Tai-Chu Lau 3 , Marc Robert 1
Organometallics ( IF 2.5 ) Pub Date : 2018-09-18 , DOI: 10.1021/acs.organomet.8b00555 Claudio Cometto 1 , Lingjing Chen 2 , Elodie Anxolabéhère-Mallart 1 , Claire Fave 1 , Tai-Chu Lau 3 , Marc Robert 1
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The electrochemical catalytic reduction of CO2 into CO could be achieved with excellent selectivity and rate in acetonitrile in the presence of phenol with cobalt 2,2′:6′,2″:6″,2‴-quaterpyridine complex [CoII(qpy)(H2O)2]2+ (Co) acting as a molecular catalyst. Upon using cyclic voltammetry at low and high scan rate (up to 500 V/s) two catalytic pathways have been identified. At a low concentration of phenol (<1 M), catalysis mainly occurs after the reduction of Co with three electrons. In that case, the selectivity for CO production is ca. 80% with 20% of H2 as by product, along with a turnover frequency of 1.2 × 104 s–1 for CO production at an overpotential η of ca. 0.6 V. The triply reduced active species binds to CO2 and the C–O bond is cleaved thanks to the acid. At very large concentration of phenol (3 M), another pathway becomes predominant: the doubly reduced species binds to CO2, while its reductive protonation leads to CO formation. As already shown, this later process is endowed with fast rate at low overpotential (turnover frequency of 3 × 104 s–1 at η = 0.3 V) and 95% selectivity for CO production. By varying the phenol concentration and the scan rate in voltammetry experiments, it was thus possible to identify, activate, and characterize several pathways for the CO2-to-CO conversion and to decipher Co electrochemical reactivity toward CO2.
中文翻译：
与钴配合物的CO 2到CO转化的分子电化学催化：循环伏安法机理研究
电化学催化还原的CO 2为CO可以具有优良的选择性和速率在乙腈中苯酚的存在下与钴2,2来实现'：6'，2“：6”，2'''-quaterpyridine复杂[CO II（QPY ）（H 2 O）2 ] 2+（Co）作为分子催化剂。在低和高扫描速率（高达500 V / s）下使用循环伏安法时，已经确定了两种催化途径。在低浓度苯酚（<1 M）下，催化主要发生在三电子还原Co之后。在那种情况下，CO生产的选择性为约。80％的产品为H 2的副产品为20％，周转频率为1.2×10 4s –1，用于在约η的超电势η下生产CO。0.6V。三重还原的活性物质与CO 2结合，并且由于酸而使C–O键断裂。在非常高浓度的苯酚（3 M）下，另一种途径变得占优势：双重还原的物质与CO 2结合，而其还原性质子化导致形成CO。如已经显示的，此后一过程具有低过电势的快速速率（η= 0.3 V时的转换频率为3×10 4 s –1）和95％的CO选择性。通过改变伏安法实验中的苯酚浓度和扫描速率，可以确定，激活和表征CO 2的几种途径-CO转化和破译Co对CO 2的电化学反应性。
更新日期：2019-02-06
中文翻译：
与钴配合物的CO 2到CO转化的分子电化学催化：循环伏安法机理研究
电化学催化还原的CO 2为CO可以具有优良的选择性和速率在乙腈中苯酚的存在下与钴2,2来实现'：6'，2“：6”，2'''-quaterpyridine复杂[CO II（QPY ）（H 2 O）2 ] 2+（Co）作为分子催化剂。在低和高扫描速率（高达500 V / s）下使用循环伏安法时，已经确定了两种催化途径。在低浓度苯酚（<1 M）下，催化主要发生在三电子还原Co之后。在那种情况下，CO生产的选择性为约。80％的产品为H 2的副产品为20％，周转频率为1.2×10 4s –1，用于在约η的超电势η下生产CO。0.6V。三重还原的活性物质与CO 2结合，并且由于酸而使C–O键断裂。在非常高浓度的苯酚（3 M）下，另一种途径变得占优势：双重还原的物质与CO 2结合，而其还原性质子化导致形成CO。如已经显示的，此后一过程具有低过电势的快速速率（η= 0.3 V时的转换频率为3×10 4 s –1）和95％的CO选择性。通过改变伏安法实验中的苯酚浓度和扫描速率，可以确定，激活和表征CO 2的几种途径-CO转化和破译Co对CO 2的电化学反应性。
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