(707e) Ligand-Assisted Electrodeposition of Copper Catalyst: Towards Electrochemical Carbon Dioxide Reduction to Multi-Carbon Products

Electrochemical CO₂ reduction powered by renewable electricity is a promising approach to mitigate the pressing CO₂-emission issues. However, rational design of electrocatalysts for CO₂ reduction has been extremely difficult due to the complex reaction networks, and the unusual high-sensitivity of this reaction to the dynamic-changes at the catalyst-electrolyte interface. Extensive efforts have been spent to design Cu-based electrocatalysts with improved activity/selectivity, including surface decoration, alloying, and particularly nano-structuring. Despite the notable progress, it is still desirable to develop efficient electrocatalysts by scalable procedures to steer the reaction pathways toward desired products and reduce reaction overpotential.

Here, we investigated CO₂ reduction on copper-electrocatalysts prepared through facile electrodepositions. Particularly, different capping-ligands were employed as additives during copper-electrodeposition, then the effects of the capping-ligands on the crystalline-structure of the deposited copper, and consequently on the performance of CO₂ electroreduction were explored. We found that the copper-electrode prepared with additive of organic-acid exhibited excellent selectivity (>45%) and activity (partial-current-density >30mA cm^-2) towards ethylene at -1.0 V vs.RHE in H-cell. Under the same conditions, electrodeposited-copper prepared with other added-ligands and additive-free copper both show much lower selectivity (~30%) towards ethylene under the same current-densities. Similar trends were observed for other multi-carbon-products. The electrochemical-active-surface-areas of these electrodes were similar, we thus conclude that the organic-acid-derived-copper is intrinsically more selective/active for CO₂ to multi-carbon conversion. We further extended our catalyst-preparation-method to gas-diffusion-electrode which can be operated under practical-relevant current-densities. Encouragingly, high ethylene selectivity (>60%) were observed with high partial-current-density (>300 mA cm^-2). Later, we will conduct detailed kinetic-analysis and physical characterizations to reveal the origin of the effect of additive-ligands on the copper catalyst structure, and further on the CO₂ reduction performance. Overall, we believe the new insights obtained in this work provide effective catalyst design principles that can guide the development of selective and active CO₂-reduction-electrolyzer.