Efficient CO2 conversion to fuels and chemicals using polymer-modified Cu electrodes

This study is led by Prof. Shaohua Shen (International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University). Both experiments including catalyst preparation, structural characterizations and catalytic performance evaluation and DFT calculations were performed.

Electrochemical CO₂ reduction reaction (eCO₂RR) that produces valuable fuel or chemical provides a sustainable and carbon-neutrality approach to address the critical issues of global warming and renewable electricity storage. However, achieving high selectivity in eCO₂RR towards economically desirable multicarbon (C₂₊) products (e.g., C₂H₄, C₂H₅OH, n-C₃H₇OH, etc.) remains challenging. Among the developed metallic catalysts that enable eCO₂RR to generate C₂₊ products, metallic copper (Cu) is the most promising, and yet the polycrystalline Cu electrode suffers from the poor selectivity, due to the various reaction intermediates and the versatile reaction pathways. Currently, designing a facile and low-cost Cu catalyst with high selectivity for CO₂RR is still challenging.

To address these challenges, the research team led by Prof. Shaohua Shen from Xi’an Jiaotong University has proposed a facile surface modification to the Cu electrode with poly (α-ethyl cyanoacrylate) (PECA) featured with electron-accepting cyano (-C≡N) and ester (-COOR) groups, derived by the anionic polymerization of surface adhered ECA, to stabilize the key intermediates for high selective C₂₊ production during eCO₂RR. In comparison to the Cu electrode, the obtained PECA decorated Cu (Cu-PECA) electrode exhibits a superior selectivity toward C₂₊ products, with FE reaching 72.6% as high at −1.1 V vs. RHE. In a flow cell, stable C₂₊ production with a high FE of 76.3% and a high current density of −145.4 mA cm⁻² could be achieved at −0.9 V vs. RHE over the Cu-PECA electrode. As revealed by electrochemical and in-situ spectral investigations as well as theoretical calculations, PECA featured with -C≡N and -COOR groups, decorated on the Cu electrode, is believed to distribute the interfacial electron density and raise the central energy level of the d-band (E_d) of Cu active sites, which inhibits the *H adsorption and stabilizes the *CO adsorption, facilitating the subsequent C-C coupling and ultimately leading to the selective generation of C₂₊ products. This work should be guidable to the design of surface decorated electrocatalysts or electrodes to steer the surface adsorption behaviors of reaction intermediates for eCO₂RR towards C₂₊ production with high activity and selectivity.

See the article:

Polyacrylate modified Cu electrode for selective electrochemical CO₂ reduction towards multicarbon products

https://doi.org/10.1016/j.scib.2024.06.014