Ni- and Co-Based MOF-Derived Ni_<i>x</i>Co_3–<i>x</i>O₄ Materials: As an Efficient Anode for Direct Methanol Fuel Cell Application

Finding inexpensive and efficient anode materials is crucial for the oxidation of methanol in the direct methanol fuel cell (DMFC), which is the key electrode reaction. Herein, we report metal-organic framework (MOF)-derived Co₃O₄, NiO, and Ni_<i>x</i>Co_3-<i>x</i>O₄ (where <i>x</i> = 1.5, 1, and 0.6) materials deposited on nickel foam as efficient anode material for methanol oxidation. Among them, NiCo₂O₄ exhibited the highest methanol oxidation activity, owing to its lowest charge-transfer resistance (0.097 Ω) and high electrochemically active surface area (1950 cm²), resulting in the lowest onset potential of 0.35 V vs Hg/HgO. The optimized Ni-to-Co ratio and synergistic effect between Ni and Co metals enable NiCo₂O₄ to achieve the highest mass activity of 151 mA mg^-1 and geometric current density of 288 mA cm^-2, demonstrating excellent durability over 14 h at 0.6 V. In addition, to optimize methanol concentration, all the electrocatalysts were tested in a range of methanol concentrations, showing 0.5 M methanol as the optimal concentration. This study focuses on optimizing the metal ratio and methanol concentration to achieve the highest catalytic activity. Additionally, this lays the foundation for developing diverse MOF-derived electrocatalysts and advancing DMFCs.