Gold-Zinc-Cobalt Deposited on Titanium as Electrocatalysts for Borohydride Oxidation

Abstract

Investigation of the electrochemical oxidation of borohydride in alkaline solutions on the ZnCo alloy deposited on the titanium surface and modified with gold nanoparticles (denoted as AuZnCo/Ti) is presented. The ZnCo alloy coatings with the thickness of ~5 µm were deposited on the titanium surface (1 x1 cm) via electrodeposition from the electrolyte described in Ref. [1]. Au crystallites were deposited on the ZnCo/Ti surface via the galvanic displacement technique. The ZnCo/Ti catalysts were immersed into the 1 mM HAuCl4 + 0.1 M HCl solution at 25 oC for 0.5, 1 and 5 min, respectively [2].The morphology, structure and composition of the prepared catalysts were examined by Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray Analysis and Inductively Coupled Plasma Optical Emission Spectroscopy. Electrocatalytic activity of the prepared catalysts was investigated towards the oxidation of borohydride by means of cyclic voltammetry, chronoamperometry and chronopotentiometry.It has been determined that the AuZnCo/Ti catalysts with Au loadings of 31, 63 and 306 µg cm-2 show enhanced catalytic activity towards electro-oxidation of BH4 – ions as compared to that of ZnCo/Ti or Co/Ti catalysts. The chronoamperometry and chronopotentiometry studies also confirmed a high electrocatalytic activity of the AuZnCo/Ti catalysts for the direct electro-oxidation of BH4 – ions as compared to that of ZnCo/Ti and Co/Ti catalysts.