Effect of hydrogen doping on the loading of titania nanotube films with copper selenide species via alternating current deposition

Abstract

Fabrication of TiO2 nanotube (TiNT) films nicely decorated with lower band gap semiconducting nanoparticles remains a challenging issue for photocatalytic and solar cell applications active under visible light irradiation. In this study, TiNT films were decorated with copper selenide species via alternating current deposition method. For the first time, to achieve uniform loading of copper selenide species inside the TiNT film, as-grown and calcined TiNT films before depositions were subjected to hydrogen doping in various solutions under DC and AC pretreatments as well as by treating TiNT in H2 atmosphere. Different pretreatments resulted in different architectures of Cu x Se-in-TiNT formed by subsequent AC deposition from the acidic Cu(II)-H2SeO3 solution allowing predictable to encase Cu2Se3, Cu2Se, CuSe, or Cu2−x Se species in nm-scaled size. Field-emission scanning electron microscopy with EDS and X-ray mapping, low-angle X-ray diffraction, and diffuse reflectance spectroscopy were applied to characterize the morphology, composition, uniformity of loading, and optical properties of the fabricated heterostructures. Except light absorption, characteristic for anatase TiO2, the additional absorption edge in the visible region is formed in the TiNT films decorated with copper selenide.