Fig. 6. (a) Sixteen repeated CVs measurements of the NiCo2O4 nanoneedle-modified/GCE sensor in 0.1 M urea to monitor the stability and reproducibility. (b) Influence of potential interferents on the voltammetry response in 0.1 M urea. (c) Calibration plot (peak current versus urea concentration) in the concentration range 0.01–5 mM.
