Abstract
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•A novel architecture of Cu/Sn electrode with tunable wettability was proposed.•The hydrophobic electrode shows a Faraday efficiency of 94.17% for HCOOH.•The hydrophobic electrode displays enlarged number of triple-phase active sites.
The aqueous electrochemical reduction of CO2 into hydrocarbon fuels has been considered as a promising route to mitigate environmental problems. However, owing to the limited mass transfer of CO2 and competition with hydrogen evolution reaction in aqueous electrolyte solution, Sn-based catalysts exhibited low current density and low Faraday efficiency (FE), especially at high overpotential. Herein, we introduced a hydrophobic surface on Cu/Sn nanowires by decoration with trimethoxy (1H, 1H, 2H, 2H-heptadecafluorodecyl) silane (FAS). In contrast to the hydrophilic electrode (FEHCOOH-76.44%, at −1.2 V vs. RHE), the hydrophobic electrode achieved a high Faraday efficiency of 94.17% towards HCOOH production at −1.2 V vs. RHE. Remarkably, the synthesized electrode achieved an excellent activity for CO2 conversion even at high overpotential (FEHCOOH-86.39%, jHCOOH-23.95 mA cm−2, at −1.4 V vs. RHE), which far exceeded other most of Sn materials. This observation could be contributed to the rich triple-phase interfaces at the hydrophobic surface, which enhanced the CO2 mass transfer and increased the selectivity of HCOOH, especially at high overpotential. It was demonstrated that increasing CO2 mass transfer flux through the reduction of the wettability of the electrode was a facile and promising approach for the improved electrochemical CO2 reduction.