Palladium Nanoparticle-Modified Graphite Electrode: A Simple and Cost-Effective Voltammetric Sensor for Micromolar Nitrite Detection in Wastewater

Nitrite concentrations >28.3 μM pose significant risks to human health and the environment. A simple, selective, and cost-effective nitrite sensor was fabricated by electrodeposition of palladium nanoparticles onto the surface of a graphite electrode (nano-Pd/GE). Palladium nanoparticles were characterized using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer, revealing an average particle diameter of ∼75 nm. For fabrication of nano-Pd/GE, electrodeposition of palladium nanoparticles onto a bare graphite electrode was carried out via cyclic voltammetry (CV). Nano-Pd/GE showed a remarkable electrocatalytic activity towards nitrite oxidation with excellent repeatability and stability. Differential pulse voltammetry (DPV) was employed under optimized conditions of pH and scan rate for determination of nitrite and exhibited a wide linear response range of 10–2430 μM, high sensitivity of 0.42 μA μM⁻ 1 cm⁻ 2 , and a low detection limit of 2.0 μM. Selectivity of the nano-Pd/GE electrode for nitrite detection was confirmed, as the presence of common interfering species resulted in only minimal changes in current response. Surface modification of the graphite electrode does not require complex procedures, indicating ease of fabrication. The optimized (nano-Pd/GE) was successfully applied for determination on nitrite in industrial wastewater samples without pretreatment steps, showing high precision and strong agreement with standard methods.