Nb2O5 Nanosheets Produced via Planar-Confined Growth on GO as a Platform for Electrochemical Sensor for Ibuprofen Detection in Surface Water

This work presents the development of an electrochemical sensor based on a glassy carbon modified with niobium pentoxide (GCE-Nb₂O₅) nanosheets to detect low concentrations of ibuprofen (IBP) in aqueous matrices. IBP is considered an emerging pollutant due to its high consumption and potential to enter water bodies through improper disposal of untreated sewage, posing a risk to marine organisms and human health. Therefore, studying techniques for detecting and removing this contaminant is crucial. The electrode was modified by depositing 10 µL of a 0.2 mg mL⁻¹ ethanol dispersion of Nb₂O₅ nanoparticles and then drying in an oven. Nb₂O₅, as the modifying agent, presented excellent chemical stability, electrical conductivity, durability, and resistance. Differential pulse voltammetry, as carried out, used an amplitude of 0.05 V and a scan rate of 0.020 V s⁻¹, yielding the best results. The supporting electrolyte was evaluated, and the acetate buffer solution 0.2 M with a pH of 4.5 presented the best performance. The obtained response showed an approximately threefold increase in cathodic peak current compared to the unmodified glassy carbon electrode. The achieved detection limit was 0.02 µM and the linear working range was evaluated from 40 to 150 µM, revealing a notable increment in peak current as the IBP concentration increased. In the interfering test, the GCE-Nb₂O₅ nanosheets showed an excellent resolution of simultaneous detection of IBP, dopamine, uric acid, ascorbic acid, and caffeine.