Hydroxyethyl cellulose-based ZnCe _0.3 Ti _0.7 O ₃ nanocomposites for sustainable applications in supercapacitors and hydrogen peroxide sensors

We report the fabrication of multifunctional nanocomposites <i>via</i> integrating ZnCe_0.3Ti_0.7O₃ nanoparticles into a hydroxyethyl cellulose (HEC)-based matrix to enhance electrical, charge storage, and sensing capabilities for sustainable energy, electronics, and biosensing applications. The dielectric and conductivity behaviors of the HEC@ZnCe_0.3Ti_0.7O₃ composites were investigated over a broad frequency (4 Hz-8 MHz) and temperature range (30-140 °C). Results showed a considerable increase in the dielectric constant at low frequencies due to interfacial and dipolar polarization, with higher values achieved upon nanoparticle incorporation. Relaxation peaks in the loss tangent shifted with temperature, indicating thermally activated dipolar processes. Composites with 1.5-3 wt% ZnCe_0.3Ti_0.7O₃ exhibited superior conductivity, attributed to enhanced ionic conduction pathways. Electrochemical analysis demonstrated strong pseudocapacitive behavior and rapid electron transfer. The optimized (S2) nanocomposite exhibited exceptional sensitivity for non-enzymatic hydrogen peroxide detection, with a wider linear range (0.05-2000 µM), higher sensitivity (0.998 µA µM^-1), and a low detection border of 0.02 µM. These results highlight the potential of HEC-based ZnCe_0.3Ti_0.7O₃ nanocomposites for high-performance energy storage, optoelectronic, and sensing devices.