Grain boundary density effect for highly selective C2+ production from CO2 reduction: Polycrystalline Cu electrocatalyst as a paradigm

Herein, polycrystalline Cu catalysts (p-Cu) with varying GB densities were fabricated by electrochemical reconstruction of mesoporous Cu2O nanocrystals with different primary particle sizes.

It is discovered that increasing GB density results in correspondingly decreased coordination number (CN) of Cu sites, which in turn contributes to the progressive enhancement of C2+ selectivity over the p-Cu catalysts. Specifically, the determined optimal GB density of 151 μm–1, corresponding to a Cu CN of 6.36, delivers a remarkably augmented C2+ Faradaic efficiency of up to 88.06 % (70.55 % for C2H4) and a C2+ partial current density as high as 722.7 mA cm–2, rendering the p-Cu ranked among the best state-of-art catalysts.