Black TiO₂ nanotube arrays fabricated by electrochemical self-doping and their photoelectrochemical performance

Herein, black TiO₂ nanotube arrays (NTAs) were fabricated using electrochemical self-doping approaches, and characterized systemically by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), UV-visible absorption spectroscopy and photoluminescence spectroscopy (PL). The as-obtained black TiO₂ nanotube arrays (NTAs) exhibited stronger absorption in the visible-light region, a better separation rate of light-induced carriers, and higher electrical conductivity than TiO₂ nanotube arrays (NTAs). These characteristics cause black TiO₂ nanotube array (NTA) electrodes to have higher photoelectrocatalytic activity for degrading anthraquinone dye (reactive brilliant blue KN-R) than the TiO₂ nanotube array (NTA) electrode. Furthermore, a synergetic action between photocatalysis and electrocatalysis was also observed. The black TiO₂ nanotube array (NTA) electrode is considered to be a promising photoanode for the treatment of organic pollutants.