A Direct Ammonia Microfluidic Fuel Cell using NiCu Nanoparticles Supported on Carbon Nanotubes as an Electrocatalyst

This work demonstrates the use of a NiCu electrocatalyst prepared by hydrothermal method with different Ni/Cu mass ratios (70:30, 50:50 and 30:70) supported on carbon nanotubes (CNTs), which was studied with regards to its electrochemical behavior in the ammonia oxidation reaction and direct ammonia microfluidic fuel cell (DAMFC) performance. XRD and SEM-EDX showed the formation of NiCu alloy while TEM showed the particles size to be 15–20 nm. Cyclic voltammetry and chronoamperometry showed that NiCu had higher catalytic activity than pure Ni and pure Cu, and that the active species was a NiCu oxyhydroxide. In DAMFC tests, 50 wt % Ni₅₀Cu₅₀/CNTs was found to be the most suitable one since it showed a 43 % higher peak power density and 65 % higher maximum current density than Ni electrode. The improved performance was attributed to the NiCu oxyhydroxides formation, which improved the anodic catalytic activity by increasing amounts of active sites and the combined electronic effect of the Ni-Cu bimetallic catalysts.