Zinc-Cobalt Alloy Deposited on the Titanium Surface as Electrocatalysts for Borohydride Oxidation

Abstract

The present work is focused on the investigation of the oxidation of BH 4 − ions in an alkaline solution on a low-cost ZnCo alloy deposited on the Ti surface. The Co and ZnCo alloy coatings were deposited on the Ti surface via electrodeposition. The morphology, structure and composition of the prepared catalysts were examined by FESEM and EDX. The activity of the fabricated catalysts was investigated toward the oxidation of BH 4 − ions by means of cyclic voltammetry and chronoamperometry. It has been determined that Co/Ti and ZnCo/Ti catalyze the oxidation of H 2 generated by the catalytic hydrolysis of BH 4 − and direct oxidation of BH 4 − ions. The H 2 oxidation current densities measured on both the catalysts are rather close and reach up to 60 mA cm −2 , whereas the borohydride oxidation current densities are ∼3-4 times higher at −0.2 V on ZnCo/Ti than those obtained on Co/Ti and Zn/Ti.

Investigation of stability of gold nanoparticles modified zinc–cobalt coating in an alkaline sodium borohydride solution

“…3a-c). The nature of anodic peak A0 recorded at AuZnCo/Ti could be ascribed to the oxidation of H 2 generated by the catalytic hydrolysis of NaBH 4 as well as to the oxidation of NaBH 4 , similarly as at the ZnCo/Ti catalyst [44]. It should be noted that anodic peak A0 at the Zn/Ti catalyst occurs at ca.…”

“…In this study, the ZnCo/Ti and AuZnCo/Ti catalysts were prepared in the same manner as described in Refs. [43][44][45]. Briefly, prior to the electrodeposition of ZnCo alloy coating on the Ti, the Ti plates with a geometric area of 2 cm 2 were degreased with acetone, pre-treated with SiC emery paper (grade 2500) and MgO powder and rinsed with deionized water.…”

“…After that, the ZnCo coatings with a thickness of ~5 μm were electroplated on the Ti surface using an electrolyte as described in Refs. [43,44]. Then, Au nanoparticles were deposited on the as-prepared ZnCo/Ti surface via the galvanic displacement technique [45] by dipping of the latter catalyst into a solution containing 1 mM HAuCl 4 + 0.1 M HCl at 25°C temperature for 0.5, 1 and 5 min, respectively.…”

Investigation of sodium borohydride and hydrazine oxidation on gold nanoparticles modified zinc–cobalt coating

“…Prior to ZnCo coating deposition, the titanium plates (1 × 1 cm) were pre-treated with SiC emery paper (grade 2500) and MgO powder, degreased with acetone, then etched in diluted H 2 SO 4 (1:1 vol) at 90°C temperature for 10 s and finally rinsed with deionized water. Then, the ZnCo coatings with a thickness of ~5 μm were deposited on the Ti surface via electrodeposition from the electrolyte containing 20 g l -1 CoSO 4 , 100 g l -1 NaOH, 40 g l -1 N-(2-Hydroxyethyl) ethylenediamine, 10 g l -1 ZnO (denoted as the ZnCo plating bath) [54][55][56]. The plating bath operated at 20 ± 2°C temperature.…”

“…Based on a strong demand for an efficient and relatively inexpensive catalyst, here we present a simple approach for fabrication of the multiple-component catalyst system containing nonprecious transition metals, such as ZnCo coating and a negligible amount of Au nanoparticles with the aim to use it as the anode in direct borohydride and hydrazine fuel cells. The ZnCo coating was electroplated on the titanium surface (denoted as ZnCo/Ti) and followed by its modification with Au nanoparticles using the galvanic displacement technique [19,24,27,28,30,54]. This electrode is termed as AuZnCo/Ti.…”