Silkworm Cocoon‐Templated Hierarchical Co ₃ O ₄ for Non‐Enzymatic Electrochemical Detection of H ₂ O ₂

Hydrogen peroxide (H 2 O 2 ) is ubiquitous in food disinfection, environmental matrices, and biological systems. Therefore, rapid, sensitive, and reliable determination of H 2 O 2 is essential for risk surveillance and quality control. Herein, spinel Co 3 O 4 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 H 2 O 2 sensing electrode (Co 3 O 4 /glassy carbon electrode (GCE)). Morphological and structural characterizations confirm the formation of phase‐pure, polycrystalline Co 3 O 4 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 H 2 O 2 . The steady‐state current exhibits a good linear relationship with H 2 O 2 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 cm 2 ·s −1 and an apparent catalytic rate constant ( k cat ) of 3.2 × 10 5 M −1 ·s −1 , indicating favorable mass transfer coupled with fast interfacial reaction kinetics. Overall, the biomass‐templated Co 3 O 4 /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 H 2 O 2 monitoring in food safety and water analysis.