Electrooxidation of ethanol to acetate on mix-phase nickel–manganese composites in alkaline environments

Abstract

Electrochemically oxidizing ethanol to acetate at the anode represents a promising alternative to the oxygen evolution reaction, enabling energy-efficient hydrogen evolution at the cathode. Herein, bimetallic NiMnO_x composites were synthesized via a hydrothermal method using nickel nitrate and potassium permanganate as precursors. Detailed electrochemical tests showed that 5NiMnO_x exhibited optimal ethanol oxidation reaction (EOR) activity (net current density: 8.8 mA cm⁻²) and a maximum acetate faradaic efficiency (FE) of 81.4% at 1.6 V vs. RHE, with stable performance over 12 h. DFT calculations demonstrated Ni doping modulates electronic structures, shifting Mn 3d bands toward the Fermi level and reducing the EOR rate-determining step barrier from 4.95 eV (pristine MnOOH) to 3.10 eV. Together, these insights highlight the potential of nickel–manganese oxides as cost-effective and stable catalysts for integrated hydrogen production and biomass-derived chemical manufacturing.