Controllable synthesis of core-sheath structured aligned carbon nanotube/titanium dioxide hybrid fibers by atomic layer deposition

Abstract Carbon nanotube (CNT)-inorganic hybrids have been extensively investigated due to their potential to become the next-generation materials for applications in energy and environment. However, the random dispersion of CNTs and the low-quality inorganic phases may hinder their use in flexible and multi-functional devices. Herein, we synthesize the multi-functional aligned CNT/titanium dioxide (TiO 2 ) hybrid fibers involving CNT-based continuous fibers coated by TiO 2 through the atomic layer deposition (ALD). The aligned CNT/TiO 2 hybrid fibers with various thicknesses of TiO 2 layer can be simply obtained by changing the ALD cycles. Microscopic analysis of the surface morphologies and structures of the as-prepared hybrid fibers confirms the conformal oxide coating on the CNT fibers. Furthermore, the tensile strength of the hybrid fiber varies little after the deposition of TiO 2 while its electrical conductivity decreases by 28.3% when the ALD cycle number is increased to 715 cycles. Due to its unique self-limiting characteristic, ALD has precise control in deposition at the atomic level and can facilitate the conformal and uniform coating of TiO 2 on the CNT fibers while preserving the alignment of CNT bundles within the fiber, which may offer a promising solution for fabricating the novel multi-functional fibers.