Stepped surface-rich copper fiber felt as an efficient electrocatalyst for the CO2RR to formate

Copper (Cu) electrocatalysts for the carbon dioxide reduction reaction (CO2RR) attract immense interest by virtue of their low cost, environmental suitability and the ability to produce diverse reduction products. However, to date, realizing high selectivity for formate on Cu electrocatalysts in water-based electrolytes remains a significant challenge. Herein, we first synthesized Cu fiber felt as an efficient and stable electrocatalyst for the CO2RR through a novel biomass carbon-templated route. Remarkably, the Cu fibers expose rich nano-scale stepped surfaces with the preferred {111} facets, endowing the Cu fiber felt with high catalytic activity for formate formation, whose faradaic efficiency reaches 71.1 +/- 3.1% in aqueous potassium hydrogencarbonate solution. Meanwhile, the Cu fiber felt exhibits good stability over 390 min of electrolysis. The present work potentially provides a new avenue of surface nanostructure design for more efficient and selective Cu electrocatalysts for the CO2RR.