Employing a MoO2@NiO heterojunction as a highly selective and efficient electrochemical ethanol-to-acetaldehyde conversion catalyst†

The electrochemical manipulation of organic compounds offers a promising alternative for the synthesis of valuable organic materials under mild conditions. In this study, the MoO₂@NiO heterostructure was successfully synthesized as an efficient thin-film electrode material for electrochemical ethanol oxidation, using amorphous Ni(OH)_x nanosheets as the precursor. During electrocatalytic ethanol oxidation, this electrode exhibited a significantly reduced overpotential, achieving a value of only 1.41 V at a current density of 50 mA cm⁻². Additionally, product analysis revealed that the heterojunction electrode demonstrated high faradaic efficiency (70%) and selectivity (80%) for acetaldehyde. The outstanding performance of this electrode can be attributed to the in situ transformation of MoO₂ species during the catalytic process. In the electrolyte, MoO₂ exists as MoO₄²⁻ and undergoes a series of processes including precipitation, dissolution, and redeposition on the electrode surface. These processes lead to the formation of a novel molecular outer layer, significantly enhancing the activity and stability of the electrode material. This study provides valuable insights into the potential replacement of anodes in the electrocatalytic oxidation of ethanol in aqueous solutions, thereby contributing to the development of more efficient and sustainable electrochemical systems.