화학공학소재연구정보센터
Journal of the Electrochemical Society, Vol.162, No.9, H571-H578, 2015
Kinetic Study of the Oxygen Reduction Reaction on alpha-Ni(OH)(2) and alpha-Ni(OH)(2) Supported on Graphene Oxide
The kinetics of the oxygen reduction reaction on alpha-Ni(OH)(2) and alpha-Ni(OH)(2) supported on graphene oxide (alpha-Ni(OH)(2)/GO) were investigated using rotating disk linear sweep voltammetry in alkaline solutions of Varying oxygen and hydroxyl concentrations. Over the full hydroxyl concentration range (0.05 M to 0.5M), alpha-Ni(OH)(2)/GO displayed higher activity than unsupported alpha-Ni(OH)(2). The electron transfer numbers were 2.9 +/- 0.2 for alpha-Ni(OH)(2), 3.4 +/- 0.1 for alpha-Ni(OH)(2)/GO at low [OH-], and 3.8-3.9 for alpha-Ni(OH)(2)/GO at high [OH-] Compared to alpha-Ni(OH)(2), alpha-Ni(OH)(2)/GO displayed higher chemical reaction rate constants and higher electron transfer rate constants. These differences suggest that the synergy between the alpha-Ni(OH)(2) catalyst and the graphene oxide support is related to increases in both the speed of the rate determining chemical step and the facility for electron transfer. The order of reaction with respect to oxygen was similar to 1 for alpha-Ni(OH)(2) and alpha-Ni(OH)(2)/GO. The order of reaction with respect to hydroxyl was, similar to 0 for alpha-Ni(OH)(2) and alpha-Ni(OH)(2)/GO. The first order reaction with respect to oxygen is precedented, but the zero reaction order with respect to hydroxyl is particular to the alpha-Ni(OH)(2) catalysts. The zero reaction order is explained by possible decoupling of solution and catalyst surface hydroxyl concentrations. (C) The Author(s) 2015. Published by ECS. All rights reserved.