Sequential and Transient Electrocatalysis of Glucose Oxidation Reactions by Octahedral, Rhombic Dodecahedral, and Cubic Palladium Nanocrystals

Palladium octahedrons (Octs), nanocubes (NCs), and rhombic dodecahedrons (Rds) bounded by (111), (100), and (110) planes, respectively, were synthesized and used as catalysts for the D-glucose oxidation reaction (GOR) in alkaline media. The specific activities of these catalysts were systematically studied to assess their performance under sequential and transient conditions. For sequential oxidation (supposedly leading to gluconolactone formation) driven by cyclic voltammetry, the activity followed the order NCs >> Octs > Rds, attributable to the preferential binding of OH to the (100) plane. Furthermore, cyclic voltammetry tests indicated high D-glucose tolerance of the catalysts and the dependence of their stability on the bounding crystalline planes. For catalysis under transient conditions at an applied fixed potential (-0.05 V vs. Ag/AgCl (3 M KCl)), Octs showed a higher current density response upon the addition of D-glucose than did NCs. However, the above response for Octs decreased upon the addition of uric acid. Comparative electrochemical analysis showed that NCs show better activity, sensitivity, and a lower D-glucose detection limit than the other nanocatalysts, and are thus the most suitable for the GOR. (C) 2016 Elsevier Ltd. All rights reserved.