Iron(III)-Doped Cuprous Oxide Nanoparticles Are Used for Nonenzymatic Glucose-Sensitive Detection

Nonenzymatic glucose sensors utilizing Cu₂O as the active material are characterized by low cost, nontoxicity, and environmental friendliness, yet they suffer from limited electrical conductivity. In this work, a series of iron(III)-doped cuprous oxide (Fe_x-Cu₂O) nanomaterials, where "x" refers to the nominal doping amount, were synthesized via a mild solution-based approach within a metal ion slow-release system constructed with sodium citrate. The performance of these materials as enzyme-free glucose sensors was systematically investigated. Characterization results indicate that Fe doping effectively modulates the crystal growth of Cu₂O, leading to a morphological evolution from well-defined cubes to truncated cubes with roughened surfaces and abundant edges, accompanied by a shift in partially exposed crystal facets from (100) to (111). Regulated by sodium citrate, the particle size was significantly reduced to approximately 250 nm, with Fe uniformly incorporated into the Cu₂O lattice in the form of Fe³⁺. Electrochemical analyses reveal that an optimal level of Fe doping (Fe_0.1-Cu₂O) markedly enhances the electron transfer capability and electrochemical active surface area of the material, which can be attributed to the introduction of impurity energy levels and the establishment of complementary redox couples involving Fe³⁺/Fe²⁺ and Cu⁺/Cu²⁺. The optimized sample exhibits an extensive linear detection range (0.05-9.65 mM), superior sensitivity (1486 μA·mM^-1·cm^-2), and remarkable stability. This study offers an effective strategy for precisely tailoring the microstructure and enhancing the electrochemical properties of metal oxides through transition metal doping, thereby facilitating the development of high-performance sensing materials.