Competition between the oxygen evolution reaction and the electrooxidation of alcohols on heteroatom-functionalized multi-walled carbon nanotubes-supported Ni oxide catalysts

Hybrid water electrolysis is a prominent route for hydrogen production that circumvents issues related to the oxygen evolution reaction (OER), the anode process in conventional water electrolysis, by integrating an alternative anode reaction. Herein, samples of nickel oxide nanoparticles supported on oxygen and nitrogenfunctionalized multi-walled carbon nanotubes were evaluated as electrocatalysts for the OER and the electrooxidation of methanol (MOR), ethanol (EOR) and glycerol (GOR). The trend of overpotentials measured at a current of 0.1 mA was OER > MOR > EOR > GOR, with slightly lower overpotentials observed for the nitrogendoped sample, which is attributed to differences in nanoparticle size and distribution, support defectiveness, and nitrogen-induced electronic effects. The production of oxygen was monitored by Differential Electrochemical Mass Spectrometry (DEMS), indicating that the competition between OER and alcohol electrooxidation can be modulated by the support properties as well as by the nature and concentration of the alcohol.