Highly sensitive detection of hydrogen peroxide based on nanoporous Fe₂O₃/CoO composites

Nanoporous (NP) Fe₂O₃/CoO composites were straightforwardly fabricated by a simple dealloying strategy. Electron microscopy characterization demonstrates that selectively etching FeCoAl ternary alloy in a low concentration of NaOH solution generates a nanoparticle structure with a typical diameter around 80 nm. Interestingly, these nanoparticles consist of open three-dimensional bicontinuous nanosponge structure with uniform pore and ligament distribution around 10 nm. The resulted sample is confirmed to be a mixture of Fe₂O₃ and CoO species based on X-ray photoelectron spectroscopy and X-Ray diffraction analysis. Without any activation pretreatment, NP-Fe₂O₃/CoO composites exhibit excellent electro-oxidation activity toward H₂O₂, such as an excellent sensing performance in a wide linear sensing region from 0.05 to 4.85 mM H₂O₂, fast amperometric response (<2s), and a lower detection limit to 0.1 μM. Along with these attractive features, the as-made composites also behave as a good anti-interference towards glucose, uric acid, dopamine, and ascorbic acid during H₂O₂ detection. Furthermore, the H₂O₂ biosensor based on NP-Fe₂O₃/CoO composites also exhibits excellent long-term stability and reproducibility.