Nat. Energy: Enhanced CO2 electroreduction to multi-carbon products in strong acid induced by surface-adsorbed iodide ions

Electrochemical CO₂ reduction (CO₂RR) to multi-carbon (C₂₊) products offers a promising solution for CO₂ valorization under ambient conditions. However, CO₂ reacts within the highly alkaline cathodic microenvironment to form (bi)carbonates, compromising both CO₂ conversion efficiency and device lifespan. Using an acidic electrolyte can mitigate this issue but suffer from competing hydrogen evolution and sluggish C-C coupling, limiting attainable activity and C₂₊ selectivity.

To this end, Prof. Yanguang Li and Prof. Lu Wang from the Institute of Functional Nano and Soft Materials of Soochow University proposed a strategy for modifying copper surfaces with iodide ions introduced via solution, which significantly enhanced CO₂RR to multi-carbon products in strong acids (pH < 1). This approach exploited the strong interaction between iodide ions and copper surface to form an iodide‑modified copper interface, markedly altering its electrochemical properties. In a strongly acidic environment, this modified interface induced a unique asymmetric *CO-*COOH coupling pathway. Compared with the conventional *CO-*CO coupling pathway, this new mechanism substantially reduced the reaction energy barrier, leading to a doubling of ethylene selectivity and, more importantly, a reduction in overpotential by ~300 mV. Furthermore, by alloying copper with a small amount of silver and optimizing the electrolyte composition, the bimetallic Cu-Ag delivered an unprecedented C₂₊ partial current density of 940 mA cm^-2 and a C₂₊ Faradaic efficiency of 75.3% at -1.08 V. This work overcomes the bottleneck of low production efficiency in acidic CO₂RR toward C₂₊ products and provides a new strategy for designing efficient and stable CO₂ electroreduction systems. Relevant results have been published in the journal of Nature Energy (DOI: 10.1038/s41560-025-01924-4).

Figure 1. Promoting effect of iodide on copper for CO₂RR to ethylene in an acid-fed flow cell.

Figure 2. Iodide-enhanced CO₂RR to C₂₊ products on bimetallic Cu-Ag.

Link to paper: https://www.nature.com/articles/s41560-025-01924-4

Title: Enhanced CO₂ electroreduction to multi-carbon products in strong acid induced by surface-adsorbed iodide ions.

Authors: Xue Ding, Binbin Pan, Baojie Fan, Qinghan Yu, Jie Xu, Yuchen Yan, Yuqing Luo, Lu Wang*, Yanguang Li*.

Editor: Guo Jia