Optimizing the activity and selectivity of glycerol oxidation over core-shell electrocatalysts

Abstract

High-performance electrocatalysts with excellent activity and selectivity hold the key to the electrochemical conversion of glycerol. Herein, well-defined bimetallic Au@Ag and trimetallic PdAu@Ag core-shelled nanoparticles were fabricated using a seed-mediated growth process and further examined as electrocatalysts for glycerol oxidation in both alkaline and acidic solutions. The activity of the catalysts was evaluated via cyclic voltammetry, linear sweep voltammetry and chronoamperometric measurements. The Au@Ag and PdAu@Ag nanoparticles are highly active in alkaline solutions, but inactive in acidic solutions. In alkaline solutions, the PdAu@Ag and Au@Ag nanoparticles show current densities of 3.94 and 2.57 mA cm−2, which are 4.3 and 25.7 times those of the commercial Pd/C and Au/C catalysts, respectively. The products of glycerol electro-oxidation were analyzed by high performance liquid chromatography (HPLC). Three major products, namely dihydroxyacetone (DHA), glyceric acid, glyceraldehyde and five minor products including oxalate acid, tartronic acid, formic acid, glycolic acid (GA) and glyoxylic acid were detected. Notably, a remarkable DHA selectivity of 70.1% was obtained from the PdAu@Ag catalyst at 0.9 V. The Au@Ag yields the largest GA selectivity of 31.6% at 1.1 V. The PdAu@Ag tends to yield more C3 products at high applied potentials.