Mass Transport Control by Surface Graphene Oxide for Selective CO Production from Electrochemical CO2 Reduction

Electrochemical CO 2 reduction is always accompanied by a competitive hydrogen evolution reaction as water is used as a hydrogen source. In addition to intrinsic activity control, geometrical factors of electrocatalysts such as their porous structure have been demonstrated to affect the reaction selectivity, but understanding its origin is still important. Herein, we demonstrate that reduced graphene oxide layers can effectively control the Faradaic efficiency for CO production of porous zinc nanoparticle electrocatalysts. Simply tuning the coverage of graphene oxide dramatically varies Faradaic efficiency for CO production from 66 to 94% even in the bicarbonate electrolyte at the same biased potential, in which the hydrogen evolution rate was notably suppressed without sacrificing CO 2 reduction to CO production rate unlike many Zn-based electrocatalysts. The graphene oxide layers are r…