Dielectric–Electrochemical Coupling in Ag@Cu-Modified Chitosan–Silica Conductive Hydrogels for H2O2 Detection

Abstract This study reports the design and synthesis of a multifunctional chitosan–silica/Ag@Cu bimetallic conductive hydrogel nanocomposite prepared via an integrated sol–gel/polymerization approach, ensuring uniform nanoparticle dispersion within the polymer matrix. Structural, morphological, and optical analyses (XRD, TEM, FTIR, and UV–Vis spectroscopy) confirmed the successful formation of a homogeneous chitosan–silica/Ag@Cu hybrid network with enhanced interfacial interactions and tunable electronic structure. Broadband dielectric spectroscopy revealed a remarkable increase in interfacial polarization and electrical double-layer formation, leading to enhanced charge transport and capacitance. The optimized ChSAg/0.6Cu nanocomposite exhibited the highest electroactive surface area, a low charge-transfer resistance of 13.2 Ω, and a high specific capacitance of 8513.3 F g⁻¹. The nanocomposite exhibits efficient electrocatalytic activity toward non-enzymatic electrochemical hydrogen peroxide (H 2 O 2 ) sensors with high sensitivity, a wide linear range from 0.01 µM to 1300 µM, and low detection limit of 0.002 µM. These results demonstrate the strong correlation between dielectric behavior and electrochemical performance, highlighting the potential of the developed hydrogel for biosensing and energy-storage applications.