Microwave irradiated nickel nanoparticles on Vulcan XC-72R carbon black for methanol oxidation reaction in KOH solution

Ni/C electrocatalysts were prepared by chemical deposition of nickel nanoparticles on Vulcan XC-72R carbon black using microwave irradiation technique. The time of microwave irradiation during the reduction step and nickel weight percentage were varied. This was found to affect the morphology of formed Ni/C powder as shown by TEM analysis. Increasing nickel weight percentage results in the formation of more aggregated deposits. The electrocatalytic activity of different Ni/C samples towards methanol oxidation reaction in KOH solution was studied by applying cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopic techniques. Ni/C electrocatalyst containing 30 wt.% Ni [Ni/C-30] shows 5.2 times higher electrocatalytic activity than that with 10 wt.% Ni [Ni/C-10]. Heating Ni/C powder into microwave oven using the pulse mode of 30 s on/10 s off forms the most stable electrocatalyst for prolonged oxidation reaction. Electrochemical impedance measurements show that Ni/C-30 electrocatalyst has the lowest impedance value of 0.022k Omega cm(2), while the highest one is for Ni/C-10 [0.331 k Omega cm(2)] in (0.4 M methanol + 0.5 M KOH) solution at 500 mV. It confirms that Ni/C-30 has the highest electrocatalytic activity towards methanol oxidation reaction. (C) 2014 Elsevier B.V. All rights reserved.