A sensitive nonenzymatic hydrogen peroxide sensor using cadmium oxide nanoparticles/multiwall carbon nanotube modified glassy carbon electrode

A simple sensing scheme for hydrogen peroxide has been described by electrochemical deposition of cadmium oxide (CdO) nanoparticles with ∼50 nm in diameter on a glassy carbon (GC) electrode modified with multiwall carbon nanotubes (MWCNT). The CdO/MWCNT modified sensor, with a surface coverage of 1.13 × 10^-8 mol/cm², displayed high synergistic electrocatalytic activity for H₂O₂. The sensor was capable of reducing H₂O₂ at -1.2 V vs. Ag/AgCl (H ₂O₂ + 2H⁺ + 2e^- → 2H ₂O) in a broad pH range. At the optimal pH 7, the sensor exhibited a detection limit of 0.1 μM, broad linearity from 0.5 to 200 μM, good reproducibility (RSD of 5.9%), and long-term stability. Uric acid, ascorbic acid and dopamine up to 100 μM provoked no signal response, attesting selectivity of the CdO/MWCNT modified electrode for hydrogen peroxide.