Electrophoretic Co-Deposition of Graphene/Metal Oxide Platelets for Composite Electrode Fabrication

Abstract

Graphene-metal oxide composites have been recently introduced as promising materials for energy storage and heterogeneous catalysis. The synergy between graphene and metal oxide enhances the performance of these composite materials in comparison to their individual components.1 Improved electrochemical properties such as high capacity and cycling stability makes graphene-NiCo2O4 composite a promising supercapacitor electrode.2 In this work, we assemble the composite electrode by electrophoresis on graphite electrode. We firstly disperse graphene sheets in the electrolyte solution by electrochemical exfoliation3 of the graphite electrode. NiCo2O4 platelets, separately prepared from Ni and Co salts by chemical synthesis route4, were then added into the electrolyte solution to form graphene sheet-NiCo2O4 platelet mixture suspension. Finally, graphene sheets and NiCo2O4 platelets are assembled on the exfoliated surface of the original graphite electrode in one electrophoretic deposition step. Deposition parameter-composite microstructure relationship was studied in detail. Controlled parameters include nominal input mass ratio of the two components, magnitude of the electrical field, and electrolyte solution composition. The final composite electrode were characterized using cyclic voltammetry and electrochemical impedance spectroscopy to estimate its functionality for supercapacitor application. Wu, Zhong-Shuai et al., Nano Energy 1, 107 (2012).Wang, Huanlei et al., Nano Research 5, 605 (2012).Parvez, Khaled et al., J. Am. Chem. Soc. 136, 6083 (2014).Joshi, Nirav et al., RSC Advances 6, 92655 (2016).