Noncovalent interactions on the electrocatalytic oxidation of ethanol on a Pt/C electrocatalyst

Abstract

Due to their environmentally friendly nature and high energy density, direct ethanol fuel cells have attracted extensive research attention in recent decades. However, the actual Faraday efficiency of the ethanol oxidation reaction (EOR) is much lower than its theoretical value and the reaction kinetics of the EOR is sluggish due to insufficient active sites on the electrocatalyst surface. Pt/C is recognized as one of the most promising electrocatalysts for the EOR. Thus, the microscopic interfacial reaction mechanisms of the EOR on Pt/C were systematically studied in this work. In metal hydroxide solutions, hydrated alkali cations were found to bind with OHad through noncovalent interactions to form clusters and occupy the active sites on the Pt/C electrocatalyst surface, thus resulting in low Faraday efficiency and sluggish kinetics of the EOR. To reduce the negative effect of the noncovalent interactions on the EOR, a shield was made on the electrocatalyst surface using 4-trifluoromethylphenyl, resulting in twice the EOR catalytic reactivity of Pt/C.