Local environment-mediated efficient electrocatalysis of CO2 to CO on Zn nanosheets

Abstract

Nowadays, the goal of carbon peaking and carbon neutrality has become a global consensus, and electrochemical CO₂ reduction to provide high-value power fuel is one of the major technical approaches attracting significant research interests and application prospects. However, the inevitable hydrogen evolution reaction in water-based electrolyte systems crowds out the reactive sites of active metals, causing a low CO₂ conversion efficiency. In this work, Zn nanosheets were prepared via electrodeposition on the surface of carbon paper and then modified with polytetrafluoroethylene (PTFE) to tune the wetting angle of the electrolyte. A CO faradaic efficiency of 90.2% was achieved for Zn NS-8% PTFE (contact angle: 136.8°) at the electrolytic voltage of −1.0 V vs. RHE along with an overall current density of −7.9 mA cm⁻². Experimental results and molecular dynamics simulation revealed that PTFE weakened the aggregation of H₂O molecules and was more beneficial for capturing and adsorbing CO₂ molecules near the electrode surface. The active sites of hydrogen production were transformed into the reaction center for electrocatalytic CO₂ reduction due to the hydrophobicity of the electrode, and the accumulation of the local CO₂ concentration accelerated the kinetic activity for electrochemical conversion (CO₂ to CO). This strategy of tuning the local environment offers an alternative approach for effective electrode manufacturing in liquid electrolytes.