Electrochemical insights into manganese–cobalt doped α-Fe ₂ O ₃ nanomaterial for cholesterol detection: a comparative approach

Herein, a self-assembled hierarchical structure of hematite (α-Fe₂O₃) was synthesized <i>via</i> a one-pot hydrothermal method. Subsequently, the nanomaterial was doped to obtain M _<i>x</i> Fe_2-<i>x</i> O₃ (M = Mn-Co; <i>x</i> = 0.01, 0.05, and 0.1) at precise concentrations. An electrode was fabricated by coating the resulting nanocomposite onto a nickel foam (NF) substrate. Electrochemical characterization demonstrated the excellent performance of cobalt-doped α-Fe₂O₃, among which Co_0.05Fe_0.95O₃ (CF5) exhibited a superior performance, showing a two-fold increase in sensitivity of 1364.2 μA mM^-1 cm^-2 (±0.03, <i>n</i> = 3) in 0.5 M KOH, a limit of detection (LOD) of ∼0.17 mM, and a limit of quantification (LOQ) of ∼0.58 mM. The Density Functional Theory (DFT) was performed to understand the doping prompting in the reduced bandgap. The fabricated electrode displayed a rapid response time of 2 s and demonstrated 95% stability, excellent reproducibility, and selectivity, as confirmed by tests with several interfering species. A comprehensive evaluation of the electrode's performance using human blood serum highlighted its robustness and reliability for cholesterol detection in clinical settings, making it a promising tool for clinical and pharmaceutical applications.