Electrochemically reconstructable CuMn-bimetal-based metal-organic framework encapsulated CoO composite for selective methanol electrooxidation.

In this work, a CuMn-bimetal-based metal-organic framework (MOF) encapsulated CoO composite (CuMn-MOF@CoO) with a three-dimensionmal hierarchical structure formed by interwoven nanosheets was in-situ grown on nickel foam (NF) through a three-step fabrication method for the electrochemical methanol oxidation reaction(MOR). The characterizations revealed the phase transformation of CuMn-MOF during the electrochemical activation generated abundant hydroxides/hydroxyoxides (Cu(OH), Mn(OH), MOOH), which provided optimal architecture and real active sites for MOR. At the same time, the combination of CoO with the generated CuMn(OH) effectively enhanced the synergistic interactions between them, greatly hindering high-valent hydroxides formation, lowering methanol and intermediate adsorption energy barriers, thereby ensuring highly selective electrooxidation of methanol to formate with high activity. As a result, the electrochemically reconstructable CuMn-MOF@CoO composite exhibited excellent performance, achieving a high MOR current density of 500 mA cm at 1.41 V vs. RHE, with a Faradaic efficiency (FE) of near 100 % and long-term stability. Moreover, in a two-electrode electrolysis system with MeOH-water solution, only 1.60 V of cell voltage was required to maintain a current density of 100 mA cm for MOR-HER, which significantly reduced energy consumption compared to the conventional OER-HER system. It opens a novel avenue for the design of advanced electrochemically reconstructable MOF-based composites for elecrooxidation process.