Fabrication of a novel gold nanospheres/activated carbon nanocomposite for enhanced electrocatalytic activity toward the detection of toxic hydrazine in various water samples

We report the preparation of a novel nanocomposite viz. gold nanoparticles (Au) decorated activated carbon (AC) modified glassy carbon electrode by a simple electrochemical approach to trace level detection of hydrazine. The morphology and chemical composition of the resultant AC/Au nanocomposite were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopic (EDX) method. The amounts of carbon, hydrogen, nitrogen and oxygen functional groups with highly porous nature of the AC may greatly inhibit the Au nanospheres on carbon surface. The electro-oxidation of hydrazine has been assessed by cyclic voltammetry, linear sweep voltammetry and amperometry method. Notably, the AC/Au nanocomposite modified GCE exhibits with a sharp peak at a very lower oxidation potential (0.13 V) with 3-fold current than the AC/GCE and Au/GCE. We obtained two linear ranges by using amperometric sensor (i) 0.44-208 μM with the sensitivity of 4.936 μA μM^-1 cm^-2 and (ii) 5-390 nM with the sensitivity of 15.18 nA μM^-1 cm ^-2. Remarkably, we achieved a very lower detection limit of 6.3 nM for the detection of hydrazine. The results reveal that AC/Au nanocomposite could be employed for the detection of hydrazine with simplicity, low cost, repeatability and stability. In addition, the proposed method was applied to determine the hydrazine in various water samples with acceptable results.