Unlocking direct CO2 electrolysis to C3 products via electrolyte supersaturation

Abstract

The electroreduction of CO2 has recently achieved notable progress in the formation of C2 products such as ethylene and ethanol. However, the direct synthesis of C3 products is considerably limited by the C2-C1 coupling reaction and the Faradaic efficiency has remained low. Here, we present a supersaturation strategy for the electrosynthesis of 2-propanol from CO2 in highly carbonated electrolytes. By controlling the CO2 concentration above the saturation limit, we developed a co-electrodeposition method with suppressed galvanic replacement to obtain a Cu-Ag alloy catalyst. In supersaturated conditions, the alloy achieved high performance for the production of 2-propanol with a Faradaic efficiency of 56.7 % and j2-propanol of 59.3 mA cm -2 . Our investigations revealed that the presence of dispersed Ag atoms in Cu weakens the surface binding of intermediates in the middle position of the alkyl chain and strengthens the C-O bonds, which favours the formation of 2-propanol over 1-propanol.

Acidic Media Impedes Tandem Catalysis Reaction Pathways in Electrochemical CO2 Reduction

“…Narrow scan X‐ray photoelectron spectroscopy (XPS) measurements of the Cu 2p and Ag 3d peaks (Figure 1b–1c) show that the peak binding energies do not shift even when the Cu/Ag composition is varied. This is consistent with the notion that Cu and Ag exist as phase separated components, because the alloyed case should result in binding energy shifts for both Cu 2p and Ag 3d peaks [36,37] . Figure 1d–1g show scanning transmission electron microscopy (STEM) imaging results of both 75CuAg and 25CuAg catalysts.…”

Acidic Media Impedes Tandem Catalysis Reaction Pathways in Electrochemical CO2 Reduction

“…This is consistent with the notion that Cu and Ag exist as phase separated components, because the alloyed case should result in binding energy shifts for both Cu 2p and Ag 3d peaks. [36,37] Figure 1d-1g show scanning transmission electron microscopy (STEM) imaging results of both 75CuAg and 25CuAg catalysts. Energy-dispersive X-ray spectroscopy (EDX) mapping confirms that Ag and Cu are indeed phase separated, with high-angle annular dark-field (HAADF) imaging showing lattice fringes that belong to specific orientations of Cu or Ag.…”

Unveiling the effects of ions in the electric double layer on the carbon dioxide reduction reaction

“…15–22 The FEs for CO 2 reduction to multi-carbon products (C 2+ ) are now above 70% on copper. 23–29 Besides, the electrodes and reactors also play significant roles in the CO 2 RR. 30,31 Generally, there are two kinds of reactors, a conventional H-type reactor and a gas diffusion electrode (GDE) based flow-cell reactor.…”