The electrochemical activity of the electrodes for oxidation of 0.5 mM nitrite was tested via the CV between 0 and 1.0 V in 0.1 M PBS (pH 7) at a scan rate of 50 mV/s (Fig. 3B). The obtained current density for nitrite oxidation using bare SPCE is 181 µA cm− 2. Moreover, the SPCE modified with Ni-PDCA demonstrated a current density of 251 µA cm− 2 at 0.72 V, a 39% enhancement in electrochemical performance over the bare SPCE. In addition, a slight reduction in Epa was observed for NiPDCA/SPCE compared to the bare SPCE. Thus, it is clear that Ni-PDCA plays a vital role in the enhancement of electrochemical nitrite oxidation, possibly due to the increased electroactive surface area.