摘要
CO_(2)电化学还原为甲酸(HCOOH)作为可再生氢的液体载体,有助于可再生能源的转变.本文使用密度泛函理论和微观动力学模拟研究了SnO_(2)电极上CO_(2)高效催化还原为HCOOH的要求.表面羟基化是实现高活性的先决条件,预测的电流密度与实验值的趋势相同.所得到的羟基化表面对HCOOH的产生具有高选择性,析氢反应的贡献可以忽略不计.机理研究结果表明,反应首先将吸附的CO_(2)加氢为羧酸盐(COOH),然后进一步加氢获得所需产物.通过采用常用元素(Bi,Pd,Ni和Cu)对表面进行掺杂,确定Bi掺杂可以显著提高电流密度.根据该机理中的两个关键步骤建立了Br?nsted-Evans-Polanyi关系.总之,羧酸盐的形成是速率控制步骤.将两个质子化步骤的自由能作为两个描述符,分析了CO_(2)还原活性,结果表明Bi掺杂SnO_(2)电极具有最高活性.
Electrochemical reduction of CO_(2) to formic acid(HCOOH)can contribute to the renewable energy transition as a liquid carrier of renewably hydrogen.Here,we investigated the catalytic requirements of SnO_(2) electrodes for efficient CO_(2) reduction to HCOOH using density functional theory and microkinetics simulations.Hydroxylation of the surface is a prerequisite to achieve a high activity with predicted current densities in agreement with experiment.The resulting surface is selective to HCOOH production with a negligible contribution of the hydrogen evolution reaction.Mechanistically,it is found that the reaction proceeds via hydrogenation of adsorbed CO_(2) to carboxylate(COOH),which is then further hydrogenated to the desired product.Doping of the surface by commonly used elements(Bi,Pd,Ni and Cu)identifies Bi as the preferred promoter to substantially improve the current density.Brønsted‐Evans‐Polanyi relations are established for the two key steps in the mechanism.Overall,carboxylate formation is the rate‐controlling step.The CO_(2) reduction activity is analyzed in terms of two descriptors,namely the free energies for the two protonation steps,showing that Bi presents the highest activity.
作者
刘赵春
宗雪
Dionisios G.Vlachos
Ivo A.W.Filot
Emiel J.M.Hensen
Zhaochun Liu;Xue Zong;Dionisios G.Vlachos;Ivo A.W.Filot;Emiel J.M.Hensen(Laboratory of Inorganic Materials Chemistry,Department of Chemical Engineering and Chemistry,Eindhoven University of Technology,P.O.Box 513,5600 MB Eindhoven,Netherlands;Department of Chemical and Biomolecular Engineering,The Delaware Energy Institute,University of Delaware,221 Academy St.,Newark,DE 19716,USA)
基金
financial support of the China Scholarship Council
