Novel bimetallic graphene-cobalt-nickel (G-Co-Ni) nano-ensemble electrocatalyst for enhanced borohydride oxidation

Electrochemically active bi-metallic nano-ensemble, Graphene-Cobalt-Nickel (G-Co-Ni) is proposed as the electro-catalyst for direct oxidation of BH4- ions. Three nano-hybrid electro-catalysts namely Graphene-Cobalt (G-Co), Graphene-Nickel (G-Ni) and Graphene-Cobalt-Nickel (G-Co-Ni) are synthesized and characterized using XRD, FTIR, Raman's spectroscopy, SEM, HRTEM, EDAX and mass absorption spectroscopy. The electrocatalytic activity of the synthesized catalysts towards the oxidation of BH4- ions was investigated by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Among the different electro-catalysts G-Co-Ni (similar to 4.5:1:1 weight ratio) exhibits the highest value of electroactive surface area (ESA = 518.6 m(2)/gm). G-Co-Ni shows enhanced mass specific activity (msa: 750-900 A g(-1)) towards the direct oxidation of BH4- ions and oxidation of H-2 generated by catalytic hydrolysis of BH4- ions comparing with G-Ni (msa: 130 -160 A g(-1)) and G-Co (msa: 120-130 A g(-1)) catalysts. The enhanced electro-catalytic activity is attributed to the increased number of reaction sites and pathways of electron transfer through graphene supported bimetals. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved,