Highly Efficient CO 2 Reduction at Steady 2 A cm -2 by Surface Reconstruction of Silver Penetration Electrode.

Electroreduction of CO 2 to CO is a promising route for greenhouse gas resource utilization, but it still suffers from impractical current density and poor durability. Here, a nanosheet shell (NS) vertically standing on the Ag hollow fiber (NS@Ag HF) surface formed by electrochemical surface reconstruction is reported. As-prepared NS@Ag HF as a gas penetration electrode exhibited a high CO faradaic efficiency of 97% at an ultra-high current density of 2.0 A cm -2 with a sustained performance for continuous >200 h operation. The experimental and theoretical studies reveal that promoted surface electronic structures of NS@Ag HF by the nanosheets not only suppress the competitive hydrogen evolution reaction but also facilitate the CO 2 reduction kinetics. This work provides a feasible strategy for fabricating robust catalysts for highly efficient and stable CO 2 reduction.