Though efficient C₂₊ production from CO₂ electrocatalytic reduction reaction (CO₂ERR) has become a promising approach to mitigate CO₂ emissions and store intermittent renewable energy, it suffers from low selectivity and undesired side reactions.

Recent studies have shown that serial hollow-fiber penetration electrodes (HPEs) can improve the CO₂ERR performance by forcing CO₂ to disperse and penetrate through the abundant pores on HPE wall, which boosts CO₂ERR kinetics.

To promote the selectivity and current density for C₂₊ products simultaneously, a research team led by Profs. CHEN Wei and WEI Wei from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences has developed a stepwise CO₂ERR strategy using Ag and Cu HPEs to reach high-rate C₂₊ production.

The results were published in Applied Catalysis B: Environmental on May 30.

In the stepwise CO₂ electroreduction, CO₂ was firstly reduced into CO over chloride ion-regulated Ag hollow-fiber penetration electrodes with a 3.2 A cm^-2 partial current density and a 90.3% faradaic efficiency of CO. Then, the chloride ion-regulated Cu hollow-fiber penetration further converted CO into C₂₊ products with 1.8 A cm^-2 partial current density and 90.5% faradaic efficiency of C₂₊ products. Both steps were steadily conducted under total current density of 2 A cm^-2 for 200 hours.

Experimental results and density functional theory calculations showed that synergetic combination of the unique penetration effect and the regulated electronic structures resulted in the superior performance toward C₂₊ production.

This work sheds light on designing electrocatalytic systems with exceedingly efficient CO₂ electroreduction of high current density and selectivity as well as good durability, which might contribute to the scalable CO₂ electroreduction applications towards high-value C₂₊ chemicals.

Schematic diagram for highly efficient ampere-level CO₂ reduction to multicarbon products via stepwise hollow-fiber penetration electrodes (Image by SARI)