Metal-Organic Framework-Derived Ni-Co@C Catalysts for Urea Oxidation in Urea/H₂O₂ Fuel Cells

Low-cost Ni-based catalysts have been widely used for urea oxidation in direct urea fuel cells. However, they suffer from issues such as high overpotential, poor stability, and low activity. Herein, we demonstrate the synthesis of a highly porous nanostructured Ni-Co@C catalyst for efficient electrooxidation of urea, via the calcination of Co-doped Ni-based metal-organic framework (Ni/Co-MOF). The porosity of the MOF-derived particles is considerably higher than the Ni/Co-MOF precursor. Furthermore, the Co doping at 30 mol% significantly increases the peak current density and reduces the overpotential of the electro-oxidation of urea. A urea/H₂O₂ fuel cell with Ni_0.7Co_0.3@C as the anode exhibits maximum power density of 3.4 and 20.0 mW cm^-2 with 0.5 M urea in 5 M KOH as anolyte at 25 and 80 °C, respectively. Thus, this work suggests that the highly porous Ni-Co@C catalysts derived from MOF templates can be used for urea oxidation and as efficient anode materials for urea-based fuel cells.