A research team led by Profs. WEI Wei and CHEN Wei from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences have reported a hierarchical micro/nanostructured silver hollow-fiber electrode to boost CO₂ electroreduction. 

The electrode reduces CO₂ to CO with CO₂ conversions exceeding 54% at a high space velocity of 31,000 mL g_cat^-1·h^-1 under ambient conditions, maintaining stable large current densities (~1.26 A·cm^-2) and high CO faradaic efficiencies (~93%). 

The results were published in Nature Communications on June 2. 

The electrochemical conversion of CO₂ into carbon-based fuels and valuable feedstocks by renewable electricity is an attractive strategy for CO₂ abatement and renewable energy consumption that can help achieve the goal of carbon neutrality.

CO is the key component of syngas, a mixture of CO and H₂ that can be directly converted into various value-added chemicals via well-developed industrial processes such as Fischer-Tropsch synthesis, methanol synthesis, etc. Therefore, CO₂ electroreduction to CO is considered one of the most promising means of obtaining cost-competitive products. However, highly efficient CO₂ conversion with high space velocity under mild conditions remains a challenge. 

The hollow-fiber electrode with hierarchical micro/nanostructures in this study is composed of only metallic silver (Ag) for electroreducing CO₂ to CO. Such a porous, hollow-fiber Ag electrode acting as a CO₂ disperser not only enhances three-phase interface reactions but also guides mass transfers during electrolysis. 

Electrochemical results and time-resolved operando Raman spectra demonstrate that enhanced three-phase interface reactions and oriented mass transfers synergistically boost CO production. 

This result provides new opportunities for heightening three-phase interface reactions and mass transfer kinetics simultaneously. In addition, it demonstrates that the micro/nanostructured Ag hollow fiber can be an ideal industrial electrode with excellent durability, representing an encouraging advancement in CO₂ electroreduction that may lead to scalable applications.