Hollow Sodium Nickel Fluoride Nanocubes Deposited MWCNT as An Efficient Electrocatalyst for Urea Oxidation

- Hollow nanocubes of sodium nickel fluoride on MWCNTs are used for urea oxidation.
- SNF-MWCNT catalysts showed much better catalytic activity than commercial Ni-C.
- SNF-MWCNT-5 ml IL yields a maximum current density of 3.12 A cm−2 mg−1.
- Direct urea/air unit fuel cell showed a promising performance at very low loading of SNF.
- Ni3+ rich surface and electronic effect between Ni and F promoted urea oxidation.

Hollow nanocubes of sodium nickel fluoride deposited on multiwall carbon nanotubes (SNF-MWCNT) have been synthesized by a facile microwave assisted process using in situ templated mechanism. Ionic liquid (IL) played an important role in synthesizing the catalysts. Physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalysts were analyzed for urea electrooxidation using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) tests. The SNF-MWCNT electrocatalyst exhibited a very high current density of 3.12 A cm−2 mg−1 at 20 mV s−1 in 0.33 M urea and 5 M KOH solution aided by their Ni3+ rich surfaces, a porous and hollow structure and a favorable electronic effect of fluorine. The catalytic activity of SNF-MWCNT for urea oxidation was found superior than the commercially available Ni-C catalyst. The direct urea/air unit fuel cell showed a very promising performance by using SNF-MWCNT-5 mL IL as anode catalyst with a low amount of loading.

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