Additive-Assisted Electrodeposition of Cu on Gas Diffusion Electrodes Enables Selective CO₂ Reduction to Multicarbon Products

Abstract

Incorporating electrocatalysts for CO 2 reduction (CO 2 R) into practically relevant reactor architectures, i.e., gas diffusion electrodes (GDEs), is crucial for the development of future CO 2 electrolyzers. In this work, we investigated the additive effects of Cu electrodeposition onto GDEs and achieved improved performance in the conversion of CO 2 to multicarbon (C 2+ ) products compared to the conventional GDE preparation methods, such as spray coating of Cu nanoparticles onto GDEs. Specifically, we prepared GDEs based on polycrystalline copper (ED Cu), acetic acid (AA)-derived Cu 2 O, and lactic acid (LA)derived Cu 2 O via direct electrodeposition. We compared the CO 2 R of these GDEs with that of a GDE prepared via spray coating of Cu 2 O nanocubes. Under the same testing conditions, LA Cu 2 O demonstrated the highest selectivity toward ethylene (∼60%) and overall C 2+ products (>80%) in a flow cell, outperforming the state-of-the-art Cu 2 O nanocubes. Additionally, LA Cu 2 O also exhibited improved stability at a high current density of 300 mA cm −2 . Experimental results indicate that the enhanced CO 2 R performance is due to the optimized electrochemically active surface area, abundance of grain boundaries/defects, etc., on the electrodeposited Cu surface. We believe that the electrodeposition method developed in this study could be a cost-effective alternative to the expensive sputtering and complicated spray coating processes for practical CO 2 R applications in the future.

Electrocatalytic CO2 Reduction for Dynamic C1, C2, and C3+ Chemistry over Electrodeposited Zn on Cu and CuZn Mesh Supports

“…Among various Cu-based bimetals, the combination of Cu and Zn has been synthesized using a variety of methods to explore new EC CO 2 reduction characteristics. − These fabrication techniques have unveiled a range of properties and high selectivity for products such as formate, CO, CH 4 , C 2 H 4 , and ethanol. Notably, electrodeposition has emerged as a prominent and straightforward method for fine-tuning the properties of overlayer metals. − Meng et al utilized potential step electrodeposition to create a Cu/Zn bimetal catalyst, achieving a Faradaic efficiency (FE) of 40.2% for C 2 H 4 . This success was attributed to the presence of Cu(0)/Cu(I) oxidation states, which facilitated *CO–*CO coupling.…”

“…This success was attributed to the presence of Cu(0)/Cu(I) oxidation states, which facilitated *CO–*CO coupling. Chen et al fabricated Cu-based gas diffusion electrodes using additive-assisted electrodeposition . By tuning crystal facets through the addition of various additives, they achieved an impressive FE of over 80% for C 2+ products, with a notable 60% FE specifically for C 2 H 4 .…”

Enhancing Cu–ligand interaction for efficient CO2 reduction towards multi-carbon products

“…4,5 Several strategies have been employed to further promote the formation of C 2+ products, such as organic modification, [6][7][8][9] alloying 10,11 and introducing a dopant, 12,13 etc. Recently, gas diffusion electrode (GDE) 14,15 based CO 2 R has largely alleviated the severe CO 2 diffusion limitations in conventional H-cells, enabling CO 2 R at an industrially relevant current density. [16][17][18][19] However, a highly alkaline environment is typically necessary for achieving high selectivity towards C 2+ products in GDE reactors.…”