A Single CeO₂/Polydopamine/Multiwalled Carbon Nanotube Hybrid Sensing Platform for Concurrent Voltammetric Monitoring...

Achieving concurrent detection of high-priority polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM) using a single sensing platform remains challenging due to their low abundance, structural similarity, and coexistence in complex environmental matrices. Herein, we present a first voltammetric sensing platform, enabling simultaneous determination of benzo[a]pyrene (BaP), pyrene (Pyr), and fluorene (Fluo) using a single-chip screen-printed carbon electrode (SPCE) modified with polydopamine (PDA)-functionalized multiwalled carbon nanotubes (MWCNTs) decorated with CeO₂ nanospheres. Structural and compositional features of the composite were investigated using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The MWCNT/PDA/CeO₂/SPCE exhibited excellent electrocatalytic activity toward the direct oxidation of BaP, Pyr, and Fluo in a methanol/water electrolyte containing LiClO₄. This enhanced performance arises from the synergistic effects, including hydrophobic interactions, π-π stacking, efficient PAH adsorption, and improved electron-transfer kinetics. The sensor enabled simultaneous determination of BaP, Pyr, and Fluo with wide linear ranges (0.5-12, 0.1-10, and 7-60 μM, respectively), high sensitivities (6.99, 9.17, and 1.24 μA/μM, respectively), and low detection limits (0.22, 0.08, and 5.55 μM, respectively), along with excellent reproducibility (RSD < 4%) and selectivity against structurally similar PAHs. The practical applicability of the sensor was demonstrated by applying it to PM samples collected from on-road and different urban environments, which were fortified with known concentrations of the target analytes, yielding recoveries of 91.4-107.5% and confirming reliable performance in complex airborne matrices. Overall, the MWCNT/PDA/CeO₂/SPCE platform enables a robust, sensitive, and selective strategy for simultaneous monitoring of multiple PAHs in environmental samples.