Ultra-sensitive 2-nitrophenol detection based on reduced graphene oxide/ZnO nanocomposites

Polyethylene glycol mediated reduced graphene oxide/zinc oxide (r-GO/ZnO) nanocomposites were synthesized by simple and cost-effective chemical reduction method using graphene oxide and zinc acetate as the precursors. The crystalline structure, morphology and thermal decomposition of the as-prepared r-GO/ZnO nanocomposites were characterized by X-ray diffraction, transmission electron microscopy and thermogravimetric analysis, respectively. Elemental composition was analyzed by energy dispersive spectra and mapping. A selective 2-nitrophenol (2-NP) sensor onto glassy carbon electrode (GCE) was fabricated with a thin-layer of synthesized r-GO/ZnO composites. Improved electrochemical responses with high sensitivity including large dynamic range and long-term stability towards the selective 2-NP were acquired using the fabricated r-GO/ZnO/GCE sensor. The calibration curve was found linear (r²: 0.9916) over a wide range of 2-NP concentrations (10.0 nM–10.0 mM). The detection limit and the sensitivity were calculated as 0.27 nM and 5.8 μA·mM^− 1 cm^− 2 respectively based on 3 N/S (Signal-to-Noise ratio). In this approach, 2-NP was detected by I-V method using r-GO/ZnO composites modified GCE electrode with very high sensitivity compared to various nanocomposites reported earlier. The synthesis of r-GO/ZnO composites using chemical reduction process is a good way of establishing sensor based r-GO/ZnO composites for toxic and carcinogenic chemicals.