In situ precipitation of Nickel-hexacyanoferrate within multi-walled carbon nanotube modified electrode and its selective hydrazine electrocatalysis in physiological pH

Hybrid nickel-hexacyanoferrate-functionalized multiwalled carbon nanotube modified glassy carbon electrode (GCE/Ni-NCFe@f-MWCNT) has been prepared using electrodeposited Ni on functionalized MWCNT modified GCE (GCE/Ni@f-MWCNT) as a template and [ Fe ( CN ) 6 ] 3 - as an in-situ chemical precipitant, without any additional linker. Characterization of the GCE/Ni-NCFe@f-MWCNT by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy and cyclic voltammetry (CV) collectively revealed that the functionalized MWCNT is effective to uptake large amount of Ni species and, in turn, substantial quantity of Ni-NCFe units within its internal structure. Cyclic voltammetry of the GCE/Ni-NCFe@f-MWCNT showed non-stoichiometric K+/e− and insertion/exertion behavior (∂Epa/∂log [KCl] = 42.9 and (∂Epc/∂log [KCl] = 117 mV/decade) due to some kinetic limitation to the insertion of K+ ion through the hydrophobic basal planes of the hybrid electrode. A quantitative model has been proposed to estimate the influencing components (underlying support, surface functional groups, basel plane, impurities, and insertion into edge-plane defects) in the formation of the hybrid Ni@f-MWCNT and, in turn, the Ni-NCFe@f-MWCNT. Electrocatalytic hydrazine oxidation on the GCE/Ni-NCFe@f-MWCNT showed 33 times enhancement in the current signal over GCE/f-MWNT in a pH 7 phosphate buffer solution. Amperometric i–t method of hydrazine detection yielded current sensitivity and calibration range of 120.2 μA/μM and 20–200 μM, respectively. The hybrid GCE/Ni-NCFe@f-MWCNT material is tolerable to other co-existing interferences such as oxalic acid, citric acid and nitrite. Finally, three different water real sample analyses were successfully demonstrated with appreciable recovery values.