The suitability of ZnO film-coated glassy carbon electrode for the sensitive detection of 4-nitrophenol in aqueous medium

Abstract

The performance of a ZnO nanoparticle-based electrochemical sensor, fabricated by different treatments of ZnO on glassy carbon electrode, was evaluated for the determination of 4-nitrophenol (4-NP) in aqueous medium. The sensing performance of ZnO film-coated GCE (ZnO/F/GCE) was compared with a variety of electrodes, which included GCEs modified with ZnO powder, RGO (reduced graphene oxide), and RGO-Nafion® composite. Among the fabricated electrodes, the ZnO film-coated electrode, prepared by dispersing the well-sonicated chloroform suspension of ZnO on the GCE, showed excellent response toward the sensitive detection of 4-NP in aqueous medium, and a significant enhancement in the reduction peak current predicted the suitability of the developed sensor. Square wave voltammetry (SWV) detection mode was applied for the determination of 4-NP. The reproducibility and accuracy of ZnO/F/GCE were evaluated in the linear concentration ranges of 0.035 μM to 1.4 μM and 2.1 μM to 6.3 μM. Appreciably low SWV detection limits of 0.008 μM and 0.02 μM were estimated. Minimal influence was observed from the interfering species, added into the sample solution, on the determination of 4-NP. The performance of the developed electrode was initially optimized for 4-NP samples prepared in-house and finally tested against two real samples collected from municipality wastewater. The recovery of the ZnO/F/GCE varied from 96.8% to 105.7%.