Comparative analysis of pH sensing performance of nitrogen-doped ZnO on screen-printed silver and carbon electrodes

This paper presents a comparative study of the electrochemical pH sensing characteristics of N-ZnO on a carbon screen-printed electrode (N-ZnO/C) and a silver screen-printed electrode (N-ZnO/Ag). The surface-morphological properties of the film were evaluated using scanning electron microscopy. Electrochemical evaluation was carried out in the presence of common salts present in physiological fluids like NaCl and KCl. Cyclic voltammetry (CV) and chronoamperometry (CA) were carried out to evaluate the response characteristics of the solution under different pHs. Electrochemical impedance spectroscopy (EIS) was carried out to determine the interfacial parameters ruling the pH sensing mechanism for different electrode configurations. The studies revealed that the carbon-based electrodes exhibit stable behavior, with a sensitivity of 17.8 nA·cm⁻²/pH and a linear correlation (r² = 0.996) across a range of acidic to basic conditions, thereby enhancing the sensor’s performance. The carbon electrodes demonstrated superior sensing properties, attributed to their improved stability and conductivity. This advancement in sensor technology offers promising potential for applications requiring reliable and precise measurements.