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.
|Proceedings of the National Academy of Sciences of the United States of America
|Published - Dec 31 2020
Bibliographical noteKAUST Repository Item: Exported on 2021-01-04
Acknowledgements: This work was supported by NSF Grant 2029442 and Rice University. H.W. is a Canadian Institute for Advanced Research (CIFAR) Azrieli Global Scholar in the Bio-Inspired Solar Energy Program. C.X. acknowledges support from a J. Evans Attwell-Welch postdoctoral fellowship provided by the Smalley-Curl Institute. This work was performed in part at the Shared Equipment Authority at Rice University. The authors acknowledge the use of Electron Microscopy Center (EMC) at Rice University. Y.L. and H.N.A. acknowledge the support from King Abdullah University of Science and Technology. T.P.S. and C.-Y.L. acknowledge startup funding from Rice University.