Enhanced electrochemical glucose sensing performance of CuO:NiO mixed oxides thin film by plasma assisted nitrogen doping

Abstract

In this study plasma-assisted nitrogen doping of a CuO–NiO mixed oxide thin film was presented. The as prepared film was also applied as a glucose sensor. The nitrogen species generated during plasma ignition resulted in a beneficial phase transformation of CuO to Cu2O. Characterisation techniques such as XRD, SEM, EIS and Hall Effect etc. measurements were utilized to study the morphology, structural features, doping profile and electrical properties of the sensing material. Device performance electrochemical testing showed that the as-developed sensor (labelled as N–CuO/Cu2O:NiO) showed an ultra-fast response time of 2.5 s with high sensitivity (1131 μA/mM.cm2). The linear range of the sensor was calculated to be up to 2.74 mM of glucose and excellent selectivity towards glucose at an applied potential of +0.67 V vs Ag/AgCl in 0.1 M NaOH electrolyte solution. The limit of detection was calculated to be 20 μM for the N–CuO/Cu2O:NiO sensor. The N–CuO/Cu2O:NiO have smaller Tafel slope compared to pristine CuO and CuO:NiO mixed oxides. Enhanced electrochemical performance of the N–CuO/Cu2O:NiO originates from the improved electronic properties of the thin film.