Development of the Morphology and the Band Gap Energy of Co–Si Nanofibers by Inserting Zirconium and Titanium with Dual Anions Intercalation Process

The plate-like structure is the most familiar morphology for conventional layered double hydroxides (LDHs) in case their structures consist of divalent and trivalent cations in their layers. In this study, nanofibers and nanoneedles of Co–Si LDHs were prepared for the first time. By the inclusion of zirconium inside the nanolayers of LDH structures, their plates were formed and transformed to nanofibers. These nanofibers were modified by the insertion of titanium to build again plate-like morphology for the LDH structure. This morphology controlling was studied and explained by a dual anions intercalation process. The optical properties of Co–Si LDHs indicated that the incorporation of zirconium within their nanolayers decreased the band gap energy from 4.4 eV to 2.9 eV. Following the same behavior, the insertion of titanium besides zirconium within the nanolayers of Co–Si LDHs caused a further reduction in the band gap energy, which became 2.85 eV. Although there is no data for the optical properties of Co–Si LDHs in the literature, it is interesting to observe the low band gap energy for Co–Si LDHs to become more suitable for optical applications. These results concluded that the reduction of the band gap energy and the formation of nanofibers introduce new optical materials for developing and designing optical nanodevices.