Cu-MOF/rGO-TiO2 nanohybrid for enhanced electrochemical detection of polystyrene microplastics

Polystyrene microplastics (PS-MPs) have emerged as a threat to aquatic environments and human health. Therefore, a reliable and sensitive technique is essential for detecting PS-MPs. In this work, a highly sensitive electrochemical sensor for the analysis of PS-MPs in water samples is presented using a glassy carbon working electrode (GCE) functionalised with a copper metal-organic framework (Cu-M)/reduced graphene oxide-titanium dioxide (Cu-M/RGT) nanocomposite. The Cu-M/RGT nanohybrid was synthesised via a hydrothermal method and characterised by XRD, FTIR, Raman, FE-SEM, XPS, and BET analyses to elucidate its structural, vibrational, morphological, surface chemical and textural properties. Electrochemical tests were conducted using CV, DPV, and EIS to examine the electrochemical performance of the fabricated electrode. The Cu-M/RGT/GCE exhibited a low charge resistance of 153.38 Ω, representing a good rate of electron transfer. The electroactive surface area of 0.186 cm 2 strongly supports increased catalytic activity and conductivity. The sensor provided a broad linear response over the concentration range of 0.001-0.01 mg mL −1 , with a sensitivity of 15.1 mA mL mg −1 cm − ², a detection capability of 0.37 µg mL −1 , an outstanding limit of quantification of 1.13 µg mL −1 , and a remarkable linearity (R² = 0.99). In interference studies, the developed Cu-M/RGT/GCE demonstrated favourable selectivity, notable repeatability, reproducibility, and stability for PS-MP detection. Furthermore, the practical applicability of the developed sensor was demonstrated using a water sample, yielding a recovery of 98-99%. Overall, Cu-M/RGT/GCE is a simple, sensitive and cost-effective tool for trace analysis of PS-MPs in water samples for environmental studies.