Cobalt-doped cerium oxide nanocrystals shelled 1D SnO₂ structures for highly sensitive and selective xanthine detection in biofluids

In this study, we prepared a three-dimensional self-supported electrocatalyst based on a thin layer of cerium oxide nanocrystals doped with cobalt heteroatoms (CeO₂-Co) and then uniformly shelled over one-dimensional tin oxide (SnO₂) nanorods supported by carbon cloth substrate. The material was used as a binder-free sensor that could nonenzymatically detect xanthine (XA) with an excellent sensitivity of 3.56 μA μM⁻¹, wide linear range of 25 nM to 55 µM, low detection limit of 58 nM, and good selectivity. A screen-printed electrode based on the material accurately detected XA in food samples as well. The achievements were resulted from synergistic effects coming from the unique core@shell formation and Co-doping strategy, which efficiently modified electronic structure of the material to expose more electroactive site numbers/types and fast charge transfer, thereby producing intrinsic catalytic properties for XA oxidation. These results suggested that the SnO₂@CeO₂-Co is potential for developing efficient sensor to detect XA with good sensitivity and accuracy in food-quality monitoring.