Electronic role of biosemiconductors with C=O bonds

In this study, the electrical conducting properties of six types of biomaterials, comprising cellulose and chitosan derived from terrestrial plants and marine products, respectively, were investigated using electron spin resonance (ESR) and Schottky junction characteristics. Kenaf, chitosan, conifer, and RCH2OH (R = C11H17O9) exhibited ESR spectra showing unpaired electrons at 295 K, demonstrating rectifying effects at room temperature. In contrast, RCOONa (C12H17O11Na) and α-chitin, which did not exhibit observable ESR spectra, showed ohmic conduction behavior. The ESR g value was used to determine the organic radical species, suggesting that electrons originate from the glycosidic C1–O1•–C4 radical in cellulose and the aminyl N•–H radical in chitosan. RCOONa and α-chitin, which possess C=O bonds, suppress electron-induced effects and consequently inhibit the transport of free radicals, resulting in ohmic conduction.