Ultrawide Hydrazine Concentration Monitoring Sensor Comprising Ir−Ni Nanoparticles Decorated with Multi-Walled Carbon Nanotubes in On-Site Alkaline Fuel Cell Operation

A highly sensitive amperometric hydrazine monitoring sensor offering an ultrawide dynamic range of 5 μM to 1 M in alkaline media (e. g., 1 M KOH) was developed via co-electrodepositing iridium-nickel alloy nanoparticles (NPs) functionalized with multi-walled carbon nanotubes (Ir−Ni−MWCNTs) on a disposable screen-printed carbon electrode. The synergistic interaction of MWCNTs with Ir−Ni alloy NPs resulted in enlarged active surface area, rapid electron transfer, and alkaline media stability with an onset potential of −0.12 V (vs. Ag/AgCl) toward hydrazine oxidation. A limit of detection for hydrazine was 0.81 μM with guaranteed reproducibility, repeatability, and storage stability alongside a superb selectivity toward ethanolamine, urea, dopamine, NaBH₄, NH₄OH, NaNO₂, and Na₂CO₃. The sensor was finally applied to on-site monitoring of the carbon-free hydrazine concentration at the anode and cathode of a hydrazine fuel cell, providing more insight into the hydrazine oxidation process during cell operation.