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

Abstract

This work presents the investigation of the electrochemical oxidation of hydrazine and sodium borohydride ions in alkaline solutions on the Au nanoparticles modified ZnCo coating surface, which was deposited on the titanium substrate (termed as AuZnCo/Ti). The AuZnCo/Ti catalysts were prepared via a facile electrochemical deposition technique followed by a simple and low-cost galvanic displacement. Scanning electron microscopy, energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy were used for characterization of the prepared catalysts surface morphology, structure and composition, whereas their electrocatalytic behaviour was investigated for the electrochemical oxidation of hydrazine and sodium borohydride in an alkaline medium using cyclic voltammetry. 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 the electrochemical oxidation of both hydrazine and sodium borohydride as compared to that of the ZnCo/Ti catalyst.

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

“…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.…”

“…[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. The surface-to-volume ratio was 1.3 dm 2 l -1 .…”

“…In our previous work [45] we have investigated the electrochemical behaviour of ZnCo/Ti and AuZn-Co/Ti catalysts in NaBH 4 and hydrazine (N 2 H 4 ) alkaline solutions and determined that both catalysts are active toward the oxidation reactions of NaBH 4 and N 2 H 4 . However, the stability and durability of the mentioned catalysts have not been thoroughly analysed in an alkaline medium and their activity toward the hydrolysis reaction of NaBH 4 remained short in detail.…”

“…For the sake of simplicity, we briefly overview the SEM images of the as-prepared ZnCo/Ti and AuZnCo/Ti catalysts as was described in detail in Ref. [45] and present them in Fig. 1 under different magnifications.…”

“…In our previous work [45], we have found that an alternative noble metal-free binary system constituted of two non-precious metals such as a ZnCo alloy and modified with negligible amounts of Au nanoparticles shows electrocatalytic activity for the oxidation of NaBH 4 and hydrazine (N 2 H 4 ) in an alkaline medium. Relaying on the necessity of the development of efficient low-cost stable and durable catalysts for DBFCs, in the present study we investigated the electrochemical stability and durability of ZnCo alloy thin layers deposited on the titanium surface (denoted as ZnCo/Ti) and those modified by a small amount of Au nanoparticles (denoted as AuZnCo/ Ti) in the alkaline NaBH 4 solutions.…”