Electrochemical detection of hydrogen peroxide based on silver nanoparticles via amplified electron transfer process

A simple electrochemical sensor platform for hydrogen peroxide (H₂O₂) using silver nanoparticles (Ag NPs) entrenched in silicate matrix (APS(SG)) is reported. The redox molecules such as potassium ferricyanide ([Fe(CN)₆]³⁻), methyl viologen (MV²⁺) and ruthenium hexamine ([Ru(NH₃)₆]³⁺) were utilized to investigate the electron transfer behavior of the APS(SG)–Ag NPs. The glassy carbon (GC) electrode modified with amine-functionalized silicate sol–gel matrix (GC/APS(SG)) exhibited a complete suppression of the electrochemical response toward MV²⁺ and [Ru(NH₃)₆]³⁺. However, GC/APS(SG) electrode displayed a twofold increase in the peak currents and fast electron transfer kinetics toward [Fe(CN)₆]³⁻ in comparison with GC electrode, suggesting that GC/APS(SG) electrode demonstrated an excellent anion exchange property. The GC electrode modified with APS(SG)–Ag NPs (GC/APS(SG)–Ag NPs) showed an improved electron transfer kinetics when neither positive nor negative charge of the electroactive species in the electrolyte. The GC/APS(SG)–Ag NP electrode was effectively further applied for the electrocatalytic and sensor applications toward H₂O₂. The present sensor exhibited the reduction of H₂O₂ at less negative potential and showed the experimental low detection limit of 25.0 µM with the sensitivity of 0.042 µA/µM. In addition, the developed APS(SG)–Ag NP-based amperometric sensor presented fast response, good stability and reproducibility.