Synthesis and characterization of a coaxial carbon-TiO2 nanotube arrays film with spectral response from UV to NIR and its application in solar energy conversion

Abstract In this paper, a facile one-step vacuum annealing process has been developed to fabricate the coaxial carbon-TiO 2 nanotube arrays (CC-TNAs) film. The obtained composite film is composed of TiO 2 nanotubes self-doped by oxygen vacancies (V . o s), and an ultrathin carbon layer covering on the outer wall of TiO 2 nanotubes. This composite film exhibited high absorbency from UV to NIR wavelength region, high electric conductivity, and photothermal effect. As a photoanode for hydrogen generation, the film showed promising light response in Na 2 S/Na 2 SO 3 aqueous solution under a broad wavelength range from UV to NIR wavelength region. The study of the working mechanism revealed that a unique non-stepped photocurrent was resulted from the photothermal effect of CC-TNAs film in the electrolyte environment. The performance of this photothermo-electrochemical (PTEC) process is determined by the co-existence of the V . o s and the coaxial carbons of TNAs. This study provides new insight into the design, preparation, and correlation between the structure and performance for new semiconductor-carbon nanocomposites.