Electrochemical Sensing of Hydrogen Peroxide Using Composite Bismuth Oxide/Bismuth Oxyselenide Nanostructures: Antagonistic Influence of Tungsten Doping

This study investigates the underlying mechanisms of hydrogen peroxide (H₂O₂) sensing using a composite material of bismuth oxide and bismuth oxyselenide (Bi2OxSey). The antagonistic effect of tungsten (W)-doping on the electrochemical behavior was also examined. Undoped, 2 mol%, 4 mol%, and 6 mol% W-doped Bi2OxSey nanostructures were synthesized using a one-pot solution phase method involving selenium powder and hydrazine hydrate. W-doping induced a morphological transformation from nanosheets to spherical nanoparticles and amorphization of the bismuth oxyselenide phase. Electrochemical sensing measurements were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). H₂O₂ detection was achieved over a wide concentration range of 0.02 to 410 µM. In-depth CV analysis revealed the complex interplay of oxidation-reduction processes within the bismuth oxide and Bi2O2Se components of the composite material. W-doping exhibited an antagonistic effect, significantly reducing sensitivity. Among the studied samples, undoped Bi2OxSeγ demonstrated a high sensitivity of 83 μA μM⁻1 cm⁻2 for the CV oxidation peak at 0 V, while 6 mol% W-Bi2OxSey became completely insensitive to H2O2. Interestingly, DPV analysis showed a reversal of sensitivity trends with 2 and 4 mol% W-doping. The applicability of these samples for real-world analysis, including rainwater and urine, was also demonstrated.