Optimized Reduction of a Graphene Oxide-MWCNT Composite with Electrochemically Deposited Copper Nanoparticles on Screen Printed Electrodes for a Wide Range of Detection of Nitrate

In this report, we demonstrate the capability of electrochemically deposited copper (Cu) nanoparticles on electrochemically reduced graphene oxide (ERGO)-multiwalled carbon nanotubes (MWCNT) composite on screen printed carbon electrodes (SPCE) for electrochemical detection of nitrate. Prior to the detection, extensive fundamental investigations on the electrochemical reduction of GO on SPCE and role of MWCNT in the reduction process and the degree of reduction have been carried out which has not been previously reported. Profiting from the complementary information obtained from electrochemical impedance spectroscopy, Raman spectroscopy, and cyclic voltammetry (CV), the role of MWCNT and optimal number of scans in CV (15 scans) for the reduction was obtained. The determination of nitrate on Cu/ERGO-MWCNT/SPCE was performed by square wave voltammetry and shows a wide linear range from 10 to 750 mu M and low limit of detection of 3.3 mu M, thereby enhancing the applicability of the developed electrode in the regions of low and high concentrations as well. The electrode was tested in tap water and the analytical capability was compared using F-test and matrix effect (4.8 %), which highlights excellent analytical ability of the Cu/ERGO-MWCNT modified electrodes to detect nitrate.