(707c) Highly Ordered Copper Nanowire Array As Active Electrocatalysts for CO2 Reduction Reaction

CO₂ upgrading is one of the key strategies to reduce CO₂ emissions. Utilizing the renewable electricity from wind and solar to electrochemically reduce CO₂, usually know as CO₂ reduction reaction (CO₂RR), shines several advantages, such as mild operation conditions, modular and scalable setups. Copper (Cu) is the unique catalyst for promoting CO₂RR to multi-carbon hydrocarbons (C₂₊) but suffers low activity and selectivity. One approach to enhance the catalytic performance of CO₂RR-to-C₂₊ is to modify the bare Cu catalysts, including oxide-derived Cu, bimetallic Cu-M, N-doped Cu, and nanostructured Cu. However, these modifications frequently require multiple steps to achieve the desired performance of Cu catalysts.

Herein, we report a novel catalyst design, i.e., Cu nanowire (CuNw) electrode with highly ordered vertical alignment, to enhance the catalytic performance of CO₂RR-to-C₂₊. The nanowire was synthesized via the template-assisted electrodeposition method. SEM imaging confirmed the formation of 200-nm diameter nanowire with needle-tip morphology (Figure 1a). We then performed CO₂RR over this CuNw using a H-cell reactor. Linear Sweep Voltammetry (LSV) study indicated a high geometric current density over the CuNw electrode, -47 mA/cm² at -1.4 V_RHE, which is about 4 times higher than that of the bulk Cu (Figure 1b). The electrochemical surface area (ECSA) measurements showed that the roughness of CuNw increased by 20- to 60-fold when compared to the bulk Cu (Figure 1c), suggesting that the high activity might come from the higher surface area of CuNw. In addition, electrochemical impedance spectroscopy (EIS) measurement showed that there is less charge transfer resistance on the CuNw electrode than the bulk Cu electrode (Figure 1d). NMR measurements showed that the partial current of CO₂RR-to-ethanol over the CuNw was 3-fold higher than that of the bulk Cu. Overall, our study provides a novel, convenient, and scalable catalyst design of ordered Cu nanowire array structure for electrocatalysis.