Direct and continuous generation of pure acetic acid solutions via electrocatalytic carbon monoxide reduction
Direct and continuous generation of pure acetic acid solutions via electrocatalytic carbon monoxide reduction
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DOI：
10.1073/pnas.2010868118
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发表时间：
2020-12
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通讯作者：
Peng Zhu;Chuan Xia;Chun-Yen Liu;Kun Jiang;G. Gao;Xiao Zhang;Yang Xia;Yongjiu Lei;H. Alshareef;T. Senftle;Haotian Wang
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作者：
Peng Zhu;Chuan Xia;Chun-Yen Liu;Kun Jiang;G. Gao;Xiao Zhang;Yang Xia;Yongjiu Lei;H. Alshareef;T. Senftle;Haotian Wang
利用电力将二氧化碳或一氧化碳还原为有价值的液体燃料可以彻底改变我们生产化学品/燃料的方式。然而，存在两种类型的杂质挑战：不同的液体产物通常在Cu催化剂上共生;此外，这些生成的液体燃料不可避免地与液体电解质中的离子杂质混合。通过合理设计Cu纳米立方体催化剂和多孔固体电解质反应器，我们报道了一种通过电化学CO还原直接连续生成高纯乙酸溶液的方法。电化学CO2或CO还原为高价值C2+液体燃料是理想的，但其实际应用受到来自共生液体产物和液体电解质中溶质的杂质的挑战，这需要成本和能量密集的下游分离工艺。通过合理的设计耦合在铜催化剂和多孔固体电解质（PSE）反应器，在这里，我们证明了直接和连续生成纯乙酸溶液通过电化学CO还原。通过优化的边-面比，Cu纳米立方体催化剂在中性pH下呈现出前所未有的醋酸盐性能，其他液体产物得到极大抑制，最大醋酸盐法拉第效率为43%，分电流为200 mA·cm−2，相对纯度高达98 wt%，连续运行150 h以上的稳定性极佳。密度泛函理论模拟揭示了阶梯网站沿着立方边缘在促进乙酸途径的作用。此外，PSE层，而不是传统的液体电解质，被设计为分离阴极和阳极，以有效的离子传导，同时不引入任何杂质离子到所产生的液体燃料。纯乙酸溶液，浓度高达2重量%（0.33 M），可以连续生产通过采用乙酸选择性铜催化剂在我们的PSE反应器。
Significance Using electricity to reduce CO2 or CO back into valuable liquid fuels can revolutionize the way we produce chemicals/fuels. However, there are two types of impurity challenges involved: Different liquid products were typically cogenerated on Cu catalysts; in addition, those generated liquid fuels were inevitably mixed with ion impurities in liquid electrolytes. By integrating the rational design of Cu nanocube catalyst and porous solid electrolyte reactor, we report a direct and continuous generation of high-purity acetic acid solutions via electrochemical CO reduction. Electrochemical CO2 or CO reduction to high-value C2+ liquid fuels is desirable, but its practical application is challenged by impurities from cogenerated liquid products and solutes in liquid electrolytes, which necessitates cost- and energy-intensive downstream separation processes. By coupling rational designs in a Cu catalyst and porous solid electrolyte (PSE) reactor, here we demonstrate a direct and continuous generation of pure acetic acid solutions via electrochemical CO reduction. With optimized edge-to-surface ratio, the Cu nanocube catalyst presents an unprecedented acetate performance in neutral pH with other liquid products greatly suppressed, delivering a maximal acetate Faradaic efficiency of 43%, partial current of 200 mA⋅cm−2, ultrahigh relative purity of up to 98 wt%, and excellent stability of over 150 h continuous operation. Density functional theory simulations reveal the role of stepped sites along the cube edge in promoting the acetate pathway. Additionally, a PSE layer, other than a conventional liquid electrolyte, was designed to separate cathode and anode for efficient ion conductions, while not introducing any impurity ions into generated liquid fuels. Pure acetic acid solutions, with concentrations up to 2 wt% (0.33 M), can be continuously produced by employing the acetate-selective Cu catalyst in our PSE reactor.