Graphitic carbon nitride-tungsten oxide nanocomposite for electro-oxidation of diclofenac in wastewater

The presence of pharmaceuticals, such as diclofenac (DFC), in water resources is a significant issue for the environment, human health, and other ecosystems. Monitoring pharmaceuticals in water is a crucial step in ensuring the sustainability of water resources and preventing further pollution, along with the associated risks. Herein, an electrochemical sensor consisting of a nanocomposite, namely exfoliated graphitic carbon nitride (g-C 3 N 4 ) incorporated with tungsten oxide (WO 3 ), was designed for detecting DFC in water and wastewater samples. The nanocomposite was prepared using the precipitation and calcination method. Characterization using FTIR, XPS, SEM, EDX, and elemental mapping confirmed that the CNWO nanocomposite exhibits a robust interfacial connection between g-C 3 N 4 and WO 3 . The glassy carbon electrode modified with CNWO exhibited improved properties, including enhanced redox abilities, the ability to efficient oxidize DFC in water, and reduced fouling on the electrode surface. The oxidation potential peak of DFC in phosphate buffer on the modified electrode was 0.59 V in cyclic voltammetry and was 0.45 V in differential pulse voltammetry. In addition, the electrode exhibited a good response, with a detection limit of 0.114 μM and a sensitivity of 1.205 μA μM −1 cm −2 in the linear range of 0.1–100 μM. The GC/CNWO demonstrated remarkable repeatability and reproducibility at various concentrations, including 20 and 100 μM. Modifying a GC electrode with CNWO nanoparticles has proven to be another reliable and efficient method in sensor designs for monitoring DFC in water and wastewater. • WO 3 and g-C 3 N 4 were synthesized and integrated to form a nanocomposite (CNWO). • The nanocomposite modified glassy carbon electrode to improve performance in detecting diclofenac. • The electrooxidation of diclofenac on GC/CNWO was controlled by diffusion- adsorption. • The limit of detection was 0.114 μM in the linear range of 0.1–100 μM. • The sensitivity was 1.205 μAμM −1 cm −2 .