Nickel carbonate (Ni2(CO3)3) as an electrocatalyst and photo-electrocatalyst for methanol electro-oxidation

Abstract

Nickel carbonate was deposited electrochemically on Pt and Pd electrode surfaces by chronoamperometry. The electrodeposited Ni₂(CO₃)₃/Pt was characterized by a variety of techniques. The electrodeposited Ni₂(CO₃)₃/Pt and Ni₂(CO₃)₃/Pd were subsequently used for electrochemical and photoelectrochemical methanol oxidation reactions. The methanol oxidation reaction was studied using cyclic voltammetry and chronoamperometry techniques in the presence of KOH and Na₂CO₃ media. The electrochemically deposited Ni₂(CO₃)₃ on Pt and Pd electrodes showed enhanced activity towards methanol oxidation in KOH and Na₂CO₃ electrolytes. Ni₂(CO₃)₃/Pt displayed the highest forward scan peak current density of 19.8 mA cm⁻² at an anodic potential of 0.08 V vs. NHE, whereas Ni₂(CO₃)₃/Pd displayed the forward scan peak current density of 5.2 mA cm⁻² at an anodic potential of 0.2 V vs. NHE in KOH medium. Additionally, Ni₂(CO₃)₃/Pt and Ni₂(CO₃)₃/Pd demonstrated good photoelectrochemical activity under UV-light irradiation in KOH and Na₂CO₃ media. An anodic peak current density of 24.1 mA cm⁻² was observed for Ni₂(CO₃)₃/Pt and 7.4 mA cm⁻² for the Ni₂(CO₃)₃/Pd electrode. The comparison in activity of the Pt and Pd electrodes and the first-row transition metal carbonates namely cobalt and nickel carbonates was suggestive of the superior activity of Ni₂(CO₃)₃/Pt and Ni₂(CO₃)₃/Pd catalysts for the electrochemical methanol oxidation reaction.