Ternary Ni–Co–Se Nanostructure for Electrocatalytic Oxidative Value Addition of Biomass Platform Chemicals

Abstract

Electrocatalytic hydrogen (H2) generation became a prime research topic in the last decade since H2 is a clean source of energy and combustion as it does not produce CO2. Conventional electrolysis is associated with the formation of oxygen via the oxygen evolution reaction (OER) at the anode. This kinetically sluggish multistep four-electron transfer OER process needs additional energy to split water. Substitution of the OER process by the easily oxidizable substrate oxidation reaction could be a lucrative way to get H2 at a much lower potential budget than the conventional one. Biomass-derived chemicals like bioalcohols (methanol, ethanol, glycerol (GlyOH), butanol, 5-hydroxymethylfurfural (HMF) obtained from hydrolysis or fermentation of biomass) could be easily oxidized to value-added commodity chemicals like formic acid, acetic acid, propionic acid, acetone, and 2,5-furandicarboxylic acid (FDCA) at the anode part of the electrolyzer. Thermodynamically, the bond dissociation energy of “C–H” and “O–H” bonds of these organic substrates is much lower than the “O–H” bond dissociation energy of water. So, to make the overall substrate oxidation reaction kinetically more feasible, an efficient electrocatalyst needs to be developed. Herein, we present a noble metal-free Ni1–xCoxSe electrocatalyst for efficient and selective conversion of alcohol molecules to value-added commodity chemicals. Particularly, Ni0.9Co0.1Se composition showed the best substrate oxidation activity compared to pristine NiSe, CoSe, and other state-of-the-art catalysts. The substrate scope is verified with methanol, ethanol, isopropanol, ethylene glycol (EGOH), GlyOH, and malic acid. Both experimental and theoretical understanding (DFT) established the fact that Co doping manipulates the NiII → NiIII OOH redox chemistry and accelerates the formation of active hypervalent Ni(Co)OOH species at a lower potential budget than NiOOH. For all catalyses, Ni0.9Co0.1Se shows superior activity with 80–100% product conversion along with a Faradaic yield of 80–95%.