Copper Aluminum Layered Double Hydroxides with Different Compositions and Morphologies as Electrocatalysts for the Carbon Dioxide Reduction Reaction

Abstract

Electrochemical CO 2 reduction (CO 2 RR) is a key technology to convert greenhouse gas CO 2 to value-added products, such as CO and formic acid (HCOOH). In the present study, twodimensional Cu-and Al-based layered double hydroxides (CuÀ Al/LDHs) were applied as CO 2 RR catalysts. The catalysts were synthesized using a simple co-precipitation method employing sodium carbonate solutions with different pH and synthesis temperatures. The elemental ratio of Cu and Al, and sheet size were controlled. The most active CuÀ Al/LDH showed a faradaic efficiency for CO generation of 42 % and one for formate generation of 22 % at the current density of 50 mA using a gas diffusion electrode system under galvanostatic conditions. Our result indicates that the sheet size of the LDH sheet is a critical parameter for determining CO 2 RR activity.

Electrochemical Reduction of CO2 With Good Efficiency on a Nanostructured Cu-Al Catalyst

“…The selectivity for C 2 H 4 production is suppressed on all Cu 2 O-Al samples with respect to that on Cu 2 O electrode, remaining below 2.1%. This outcome is in good agreement with the results reported by Honma et al (Iwase et al, 2022), while it is inconsistent with those observed by Sargent et al (Zhong et al, 2020) potentials are shown in Supplementary Figure S3. All Cu 2 O-Alx samples show similar j total at each potential, which is much higher than the one obtained on Cu 2 O electrode at the same potential.…”

“…The selectivity for C 2 H 4 production is suppressed on all Cu 2 O-Al samples with respect to that on Cu 2 O electrode, remaining below 2.1%. This outcome is in good agreement with the results reported by Honma et al ( Iwase et al, 2022 ), while it is inconsistent with those observed by Sargent et al ( Zhong et al, 2020 ). Honma et al synthesized two-dimensional Cu- and Al-based layered double hydroxides (Cu−Al/LDHs) using a simple co-precipitation method employing sodium carbonate solutions with different pH and synthesis temperatures.…”

“…It is also observed that the selectivity for C 2 H 4 production remains below 3.0% in 2.0 M KHCO 3 . Compared with the results reported by Honma et al ( Iwase et al, 2022 ) and by Sargent et al ( Zhong et al, 2020 ), it is likely that the employed electrolyte plays a vital role on the selectivity. To understand better this aspect, the Cu 2 O-Al-3 was further tested in a flow cell with 1.0 M KOH electrolyte.…”

“…On contrast, Cu-Al materials are scarcely studied for the electrochemical CO 2 RR. Honma et al ( Iwase et al, 2022 ) studied two-dimensional Cu- and Al-based layered double hydroxides with different Cu/Al ratios and sheet sizes, and obtained the best CO faradaic efficiency (FE) of 42% and the highest formate selectivity of 22% at 50 mA cm −2 under galvanostatic conditions. Sargent et al ( Zhong et al, 2020 ) identified a Cu-Al catalyst using density functional theory calculations in combination with active machine learning, which efficiently reduced CO 2 to C 2 H 4 with a high FE over 80%.…”

Activity switching of Sn and In species in Heusler alloys for electrochemical CO2 reduction

“…The CO 2 RR activity of Heusler alloy catalysts was evaluated using a CO 2 -saturated 1 M KHCO 3 solution under galvanostatic conditions with a custom-made gas diffusion electrode cell setup. 26,27 First, Heusler alloy catalysts, Ni 2 MnIn and Ni 2 MnSn, and pure In and Sn particles were measured at 25 mA. The pure In and Sn particles were measured since they are known to generate formate (or HCOOH) via the CO 2 RR.…”