Research Information System
ELECTROCHIMICA ACTA, vol.560, 2026 (SCI-Expanded, Scopus)
Broadband impedance spectroscopy (20 Hz-10 MHz, 300-420 K, Delta T = 5 K) was used to probe charge transport and relaxation in pure fibroin and fibroin-TiO2 nanocomposites (0.1-1 wt%) containing pristine (non-irratiated) and neutron-irradiated nanoparticles. Pure fibroin shows a single non-Debye relaxation with a temperature-shifted Z ''(f) loss peak and depressed Nyquist semicircles that contract on heating. Bombyx mori cocoons were degummed by boiling in deionized water containing 0.2 g Na2CO3 (1 L, 30 min), rinsed, and dried. The extracted fibroin was dissolved in 10.5 M LiBr (60 degrees C, 4 h) and purified by dialysis against deionized water (40 degrees C, 48 h) to obtain an aqueous fibroin solution. Adding pristine TiO2 lowers Z ', shifts dispersion knees and Z '' peaks to higher frequencies, and reduces Nyquist arc diameters. At matched loading, neutron-irradiated TiO2 yields a further right-shift of Z '' peaks, smaller arcs, and shorter Cole-Cole times (up to similar to 2x at 1 wt% near 420 K), indicating accelerated interfacial and bulk equilibration. The enhancement arises from two parallel defect channels in TiO2: neutron-transmutation vanadium (Ti -> V) dopants and Ti3+/oxygen-vacancy states, which lower activation barriers and interfacial resistance. The spectra are captured by a single Cole-Cole element or an [R-b parallel to CPEb]+[R-int parallel to CPEint] circuit. Neutron-modified TiO2 offers a materials-efficient lever to tune dielectric dispersion and conductivity in fibroin composites for flexible bio-dielectrics, sensing, and frequency-selective components.