Silkworm Cocoon-Templated Hierarchical Co3O4 for Non-Enzymatic Electrochemical Detection of H2O2

Abstract

Hydrogen peroxide (H₂O₂) is ubiquitous in food disinfection, environmental matrices, and biological systems. Therefore, rapid, sensitive, and reliable determination of H₂O₂ is essential for risk surveillance and quality control. Herein, spinel Co₃O₄ with a hierarchical porous architecture was prepared via a biomass-templated impregnation-calcination strategy using natural silkworm cocoons and subsequently employed to fabricate an enzyme-free electrochemical H₂O₂ sensing electrode (Co₃O₄/glassy carbon electrode (GCE)). Morphological and structural characterizations confirm the formation of phase-pure, polycrystalline Co₃O₄ with a uniform nanoscale texture, which provides abundant accessible active sites and efficient mass-transport pathways. Under the optimized working potential of −0.4 V, chronoamperometric measurements reveal fast, stable, and highly reproducible stepwise current responses toward H₂O₂. The steady-state current exhibits a good linear relationship with H₂O₂ concentration over 4–3160 μM, delivering a sensitivity of 0.284 μA μM⁻¹·cm⁻² and a detection limit of 1.6 μM. The sensor shows strong tolerance to common inorganic salts and biologically relevant interferents, retaining 90.34% of its initial response after 18 d. Excellent repeatability and electrode-to-electrode reproducibility are achieved with relative standard deviations (RSDs) of 4.11% and 3.64%, respectively, and satisfactory recoveries of 99.7%–104.6% (RSD < 2.5%) are obtained in spiked tap-water samples. Kinetic analysis yields an apparent diffusion coefficient (D_app) of 1.2 × 10⁻⁵ cm²·s⁻¹ and an apparent catalytic rate constant (k_cat) of 3.2 × 10⁵ M⁻¹·s⁻¹, indicating favorable mass transfer coupled with fast interfacial reaction kinetics. Overall, the biomass-templated Co₃O₄/GCE achieves a balanced performance in terms of a wide linear range, low detection limit, and high reliability without resorting to complicated compositing or conductive additives, offering a green and straightforward enzyme-free electrochemical platform for H₂O₂ monitoring in food safety and water analysis.