Catalysis of the D-glucose Oxidation Reaction Using Octahedral, Rhombic Dodecahedral, and Cubic Pd@Pt Core-Shell Nanoparticles

Abstract

Sequential and transient electrocatalysis of d-glucose oxidation reactions (GORs) were studied using core-shell Pd@Pt particles with octahedral (Pd@PtOct, 76.2 nm), rhombic dodecahedral (Pd@PtRD, 79.3 nm), and nanocubic (Pd@PtNC, 62.7 nm) geometries to determine the reaction mechanism. The resulting currents and in situ frequency changes, measured using an electrochemical quartz crystal microbalance, clearly revealed that the molar ratios of electron to d-glucose mass were 1.24 and 1.22 for the sequential catalysis of the glucose oxidation by Pd@PtOct and Pd@PtNC, respectively; however, a higher ratio of 2.22 was observed for Pd@PtRD. The GORs catalyzed by Pd@PtOct and Pd@PtNC occurred via a one-electron pathway to produce gluconate, whereas the GOR catalyzed by Pd@PtRD occurred via a two-electron mechanism to generate δ-gluconolactone. A comparison based on the same electrochemical surface areas suggested that Pd@PtOct and Pd@PtRD have slightly higher activities than that of Pd@PtNC. The amperometric curves of transient catalysis at −0.05 V vs. Ag/AgCl revealed that the oxidative current density of the tested catalysts after 200 s follow the order of Pd@PtOct > Pd@PtNC > Pd@PtRD.