The manuscript by Li et al. carries out a thorough literature survey to evaluate the catalytic performance, the economic potential and environmental impact of CO2R to C1 products with ionic liquids (ILs) as (co)-electrolytes. Representative target C1 products, including CO, syngas, CH4, and CH3OH, are specifically discussed and comprehensively compared, where ILs can enhance the CO2 absorption and stability of the intermediate and reconstruct the electrode interface. The paper is well-organized and systematic, displaying the visionary discussions, which can guide the researchers to further optimize the CO2R system to increase the economic benefit and minimize the environmental hazard. Therefore, I would like to recommend a minor revision before acceptance to address the some potential concerns listed below.
1. I would suggest giving some concise description or summarization on the structure design of ILs toward efficient and highly-selective CO2R. This part might be placed in Outlook, or Section 2.5, or as an individual Section.
2. As we all know, the stability is also a crucial factor for consideration of industrial implementation of CO2R technology, while in Table 1, mainly FE, current density and cell voltage (energy efficiency) are inspected for different C1 products. Therefore, how does the ILs-assisted CO2R system behave in terms of stability? Are the summarized researches in this review preformed in H-cell or GDE (gas-diffusion-electrode) based electrolyzer? What are the impacts of ILs-containing electrolyte on stability of GDE, and the impacts of ILs-induced reconstruction on the stability of electrocatalyst?
3. In Section 4 Conclusions, while the remaining challenges have been proposed, the authors are suggested to give some future directions or strategies to address these problems, especially for promoting the economic and environmental properties of other C1 products.
4 The authors should carefully check the whole manuscript to address those possible errors in expression. For instance, in table 1, the unit of Current density is spelled wrongly. In Paragraph 2, Cu is not a noble metal. The electrocatalyst research also covers the molecular catalyst and single-atom catalyst. Etc. In addition, I suggest incorporating more related literatures to enrich the background and discussions (e.g., Energy Environ. Sci., 2022, 15, 3603-3629; J. Am. Chem. Soc., 2021, 143,3808-3816; etc.).