Amorphous cobalt–nickel borides boost electrocatalytic ethanol oxidation coupled with energy-saving hydrogen production

Abstract

The thermodynamically more advantageous ethanol oxidation (EOR) can replace anodic oxygen evolution (OER) in electrolysis, offering a practical way to produce energy-efficient hydrogen and simultaneously upgrade biomass. Here, we design an amorphous heterogeneous catalyst composed of boride (NiCoB) and tungstate (NiCoWO₄) by a simple one-step chemical reduction method. Benefiting from the amorphous structure and interactions between multiple components, the NiCoB@NiCoWO₄ catalyst shows superb EOR performance. Combined with a high efficiency hydrogen evolution catalyst (Pt/C), the NiCoB@NiCoWO₄-assisted EOR electrolysis achieves a 19-fold increase in the H₂ production rate compared to water electrolysis at 1.50 V (cell voltage). Meanwhile, the catalyst oxidizes ethanol to acetic acid at the anode as a value-added by-product, which has a high Faraday efficiency surpassing 97%. The energy efficiency of chemical hydrogen production is improved by the NiCoB@NiCoWO₄-catalyzed EOR, which has a 206 mV lower input voltage than the standard OER and achieves a current density of 20 mA cm⁻² in a three-electrode system. The present research paves the way for designing and developing efficient transition metal boride electrocatalysts for oxidative upgrading of organic molecules as well as energy-saving H₂ production.