Electrochemical and spectroelectrochemical analyses of hydrothermal carbon supported nickel electrocatalyst for ethanol electro-oxidation in alkaline medium

This paper presents the study of a simple and fast method to prepare an activated hydrothermal carbon supported nickel electrocatalyst (Ni/aHC) for ethanol oxidation reaction (EOR) in alkaline medium. The cyclic voltammogram obtained for the Ni/aHC sample in a 1.0 mol L-1 NaOH solution shows an anodic and a cathodic peak. These redox couple reaction peaks can be related to the reversible formation of (NiO)OH. The catalytic activity of the Ni/aHC sample regarding the EOR is clearly evident from the cyclic voltammogram obtained in presence of ethanol, where a significant increase in the current density from 0.55 V vs. Hg/HgO is observed. This potential value, related with the onset potential (E-onset) of the EOR, is very close to the corresponding (NiO)OH formation potential, confirming that this species is directly involved in the EOR on the Ni/aHC electrocatalyst. The in-situ Attenuated Total Reflectance FTIR (in-situ ATR-FTIRS) spectra of this sample show two intense peaks related with acetate ion formation. Based on the ATR-FTIRS and electrochemical analyses, and in the literature information, a reaction pathway of the EOR on Ni/aHC in alkaline medium is proposed. (C) 2016 Elsevier B.V. All rights reserved.