An Iron Electrocatalyst for Selective Reduction of CO2 to Formate in Water: Including Thermochemical Insights
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- 作者：Atefeh Taheri ; Emily J. Thompson ; James C. Fettinger ; Louise A. Berben
- 刊名：ACS Catalysis
- 出版年：2015
- 出版时间：December 4, 2015
- 年：2015
- 卷：5
- 期：12
- 页码：7140-7151
- 全文大小：714K
- ISSN：2155-5435
文摘
C鈥揌 bond formation with CO2 to selectively form products such as formate (HCOO鈥?/sup>) is an important step in harnessing CO2 emissions as a carbon-neutral or carbon-negative renewable energy source. In this report, we show that the iron carbonyl cluster, [Fe4N(CO)12]鈭?/sup>, is an electrocatalyst for the selective reduction of CO2 to formate in water (pH 5鈥?3). With low applied overpotential (230鈥?40 mV), formate is produced with a high current density of 4 mA cm鈥? and 96% Faradaic efficiency. These metrics, combined with the long lifetime of the catalyst (>24 h), and the use of the Earth-abundant material iron, are advances in catalyst performance relative to previously reported homogeneous and heterogeneous formate-producing electrocatalysts. We further characterized the mechanism of catalysis by [Fe4N(CO)12]鈭?/sup> using cyclic voltammetry, and structurally characterized a key reaction intermediate, the reduced hydride [HFe4N(CO)12]鈭?/sup>. In addition, thermochemical measurements performed using infrared spectroelectrochemistry provided measures of the hydride donor ability (hydricity) for [HFe4N(CO)12]鈭?/sup> in both MeCN and aqueous buffered solution. These are 49 and 15 kcal mol鈥?, respectively, and show that the driving force for C鈥揌 bond formation with CO2 by [HFe4N(CO)12]鈭?/sup> is very different in the two solvents: +5 kcal mol鈥? in MeCN (unfavorable) and 鈭?.5 kcal mol鈥? in water (favorable).