Electrochemical and Photoelectrochemical Bimodal Sensor Based on Copper Modified g‐C3N4 for Nitrate Detection

Nitrates (NO3-) are crucial in agricultural practices and the food industry, but their excessive presence in water can lead to adverse health effects. Their leaching into water sources necessitates regular monitoring. This study introduces a novel bimodal electrochemical (EC)/photoelectrochemical (PEC) sensor, utilizing copper-modified graphitic carbon nitride (Cu/g-C3N4), designed for precise nitrate determination. The structural morphology and chemical composition of the Cu/g-C3N4 nanocomposite were meticulously examined using Transmission Electron Microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). The optimization of copper loading in g-C3N4 was conducted, and the electrochemical behavior and light irradiation interaction of various Cu/g-C3N4 nanocomposites were systematically studied. The investigation revealed that 20 % Cu/g-C3N4 represented the optimal doping ratio, establishing the most promising candidate for NO3-. Nitrates were consistently measured using both EC and PEC techniques, yielding Limits of Detection (LoD) of 3.75 and 9.60 ppm, respectively. The sensor‘s robust performance was further demonstrated in the presence of possible interferents. The proposed sensors were also successfully used to detect NO3- in commercial water. This bimodal sensor presents a promising approach for accurate nitrate determination, attesting to its potential for effective cross-validation.