Highly porous self-assembled nanostructured Ni@C and NiO@C were synthesized via calcination of a Ni-based metal–organic framework. The morphology, structure, and composition of as synthesized Ni@C and NiO@C were characterized by SEM, FIB-SEM, TEM, and XRD. The electro-catalytic activity of the Ni@C and NiO@C catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the Ni@C had a higher residual carbon content and a higher specific surface area than NiO@C, thus exhibiting an enhanced electrochemical performance for urea oxidation. A direct urea fuel cell with Ni@C as an anode catalyst featured an excellent maximum power density of 13.8 mW cm⁻² with 0.33 M urea solution in 1 M KOH as fuel and humidified air as oxidant at 50 °C, additionally showing excellent stability during continuous 20-h operation. Thus, this work showed that the highly porous carbon-supported Ni catalysts derived from Ni-based metal–organic framework can be used for urea oxidation and as an efficient anode material for urea fuel cells.

Ni-based catalysts have been considered as an efficient anode material for urea fuel cells due to the low cost and high activity in alkaline media. Herein, we demonstrate that Ni-Co bimetallic nanoparticles decorated carbon nanotube aerogels as catalysts for urea oxidation reaction (UOR) can be synthesized by a polyol reduction and sol-gel method. The morphology, structure, and composition of the Ni-Co/MWCNT aerogels were characterized by scanning electron microscopy and X-Ray diffraction. The electro-catalytic activity of the Ni-Co/MWCNT aerogels towards UOR was investigated using cyclic voltammetry. It was found that the Co-doping at 25% (Co/Ni) significantly increased the oxidation peak current and reduced the overpotential of the UOR. Furthermore, the MWCNT aerogel support also remarkably enhanced electro-catalytic activity by providing a high surface area and fast mass transport for the UOR owing to the porous 3D network structures with uniform distribution of Ni-Co nanoparticles. Urea/O₂ fuel cell with Ni-Co/MWCNT aerogel as anode material exhibited an excellent performance with maximum power density of 17.5 mWcm⁻² with an open circuit voltage of 0.9 V. Thus, this work showed that the highly porous three-dimensional Ni-Co/MWCNT aerogel catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.