The electrochemical CO2 reduction into useful chemicals and fuels provides a green and sustainable means of storing electrical energy in the form of carbon-containing compounds. To study this problem at the system level, we designed a gas-fed CO2 electrolyzer incorporating a bipolar membrane (BPM) separator. The continuous production of H+ and OH- ions from water autodissociation in the BPM enables the electrolyzer to operate at high current density for over 12 hours without obvious degradation. The observed low CO faradaic efficiency in the electrolyzer may be due to the acidic environment on the cation exchange layer (CEL) side of the BPM. This problem can be partially mitigated by using a BPM with 3D junction and sulfonated poly(ether ether ketone) (SPEEK) CEL. The discovery of efficient and selective CO2 reduction catalysts has been the topic of intensive research efforts. We developed a fluorescent-based combinatorial screening method to search for ternary and quaternary metallic alloy compounds as candidates for electrochemical CO2 reduction. With the help of a carefully chosen fluorescent indicator, the change in the local proton concentration that accompanies CO2 reduction can be converted to a visible fluorescence signal. Catalyst arrays containing binary, ternary and quaternary combinations are being screened to identify active catalysts in new regions of composition space for CO2 reduction.

Electrocatalytic reduction of gaseous CO2 with a bipolar membrane-based electrolyzer and combinatorial screening of ternary and quaternary alloy catalysts

256th National Meeting (2018)

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