YUNHA JUNG

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• Selective and High Current CO2 Electro-Reduction to Multicarbon Products in Near-Neutral KCl Electrolytes. Journal of the American Chemical Society Zhang, X., Li, J., Li, Y., Jung, Y., Kuang, Y., Zhu, G., Liang, Y., Dai, H. 2021

  Abstract

  Reducing CO2 to value-added multicarbon (C2+) fuels and chemicals using renewable energy is a viable way to circumvent CO2 buildup in the atmosphere and facilitate closing the carbon cycle. To date it remains a challenge to achieve high product selectivity and long-term stability of electrocatalytic carbon dioxide reduction reaction (CO2RR) especially at practically relevant high current levels >100 mA cm-2. Here, we report a simple electrodeposited Cu electrocatalyst on a hydrophobic porous gas-diffusion layer (GDL) electrode affording stable and selective CO2RR to C2+ products in near-neutral KCl electrolytes. By directing the CO2 stream to fully submerged hydrophobic GDLs in a H-cell, high C2+ partial current densities near 100 mA cm-2 were achieved. In a flow-cell setup, the Cu/GDL cathode in 2 M KCl afforded stable CO2RR superior to that in widely used KOH electrolytes. We found that Cu etching/corrosion associated with trace oxygen played a role in the catalyst instability in alkaline media under cathodic CO2RR conditions, a problem largely suppressed in near-neutral electrolyte. A two-electrode CO2 electrolyzer was constructed with a Cu/GDL cathode in KCl catholyte and an anode comprised of nickel-iron hydroxide on nickel foam (NiFe/NF) in a KOH anolyte separated by Nafion membrane. By periodically adding HCl to the KCl catholyte to compensate the increasing pH and remove accumulated (bi)carbonates, we observed little decay over 30 h in flow-cell CO2RR activity and selectivity at 150 mA cm-2 with a high Faradaic efficiency (FE) of 75% and energy efficiency of 40% for C2+ products.

  View details for DOI 10.1021/jacs.0c13427

  View details for PubMedID 33617245