In situ construction of N/Ti3+ codoped triphasic TiO2 layer on TiO2 nanotube arrays to improve photoelectrochemical performance

Different numbers of N/Ti3+ codoped triphasic TiO2 layer are deposited on TiO2 nanotube arrays by hydrothermal reaction of TiN and TiO2 nanotube arrays. The crystal structure, morphology, and composition of the as-prepared samples and their photoelectrochemical properties are investigated and discussed. There are obviously red shift of the optical edge and enhanced visible light absorption for the resulting samples in the ultraviolet-visible diffuse reflectance spectroscopy. Besides, the photoelectrochemical tests indicate that the N/Ti3+ codoped triphasic TiO2-TiO2 nanotube array samples exhibit an enhanced photocurrent density and photovoltage under visible light irradiation. The maximum photoconversion efficiency of N/Ti3+ codoped triphasic TiO2-TiO2 nanotube array sample is 2.1 times higher than that of pristine TiO2 nanotube arrays. In addition, reduced impedance, higher carrier density, and excellent stability of photoelectrochemical performance of N/Ti3+ codoped triphasic TiO2-TiO2 nanotube array samples are also demonstrated. Finally, a plausible mechanism for the charge migration and separation on N/Ti3+ codoped triphasic TiO2-TiO2 nanotube array samples is proposed. This study provides a novel strategy to design and fabricate visible-light-driven TiO2 based composites and promote their applications in the field of solar energy utilization. (c) 2018 Elsevier Ltd. All rights reserved.