Black TiO₂ nanotube arrays for high-efficiency photoelectrochemical water-splitting

Abstract

Black titania nanotube arrays are prepared for the first time, which exhibit an excellent photoelectrochemical water-splitting performance.

Optimization of boron-doping process of titania nanotubes via electrochemical method toward enhanced photoactivity

“…In the case of doped material, the significant increase in photocurrent compared to pristine titania nanotubes is observed in the wide potential range from −0.6 up to +0.9 V vs. Ag/AgCl/0.1 M KCl. This increase in resulting from electrode illumination is significantly higher than reported by others [15,22,61] , indicating that proposed experimental approach could be regarded as an attractive alternative for other doping methods. The improved photoelectrochemical properties could be assigned to the boron doping which lead to bandgap narrowing, conductivity improvement, and inhibition of charge carrier recombination processes.…”

Black Titanium Dioxide Nanomaterials in Photocatalysis

“…The typical crystalline/amorphous core/shell structure was observed in almost all Al-reduced black TiO 2 [9,32,37,38,41], except for the black TiO 2 nanotubes [53]. Also, Ti 3+ and oxygen vacancy defects were commonly detected in Al-reduced black TiO 2 [9,32,37,38,41,53]. In a typical synthesis of the Alrecued black TiO 2 , aluminum and pristine TiO 2 (Degussa P25) were placed separately in a two-zone tube furnace (Figure 8(a)); the pressure in the tube was controlled at a base pressure below 0.5 Pa, and then in order to trigger the reduction reaction, aluminum was heated at 800°C while TiO 2 was heated at 300-500°C for 6 h [32].…”

“…Huang's group has reported on the synthesis of a series of black TiO 2 nanomaterials by aluminum reduction [9,32,37,38,41,53]. The typical crystalline/amorphous core/shell structure was observed in almost all Al-reduced black TiO 2 [9,32,37,38,41], except for the black TiO 2 nanotubes [53]. Also, Ti 3+ and oxygen vacancy defects were commonly detected in Al-reduced black TiO 2 [9,32,37,38,41,53].…”

“…It was proposed that improved photocatalytic performance of slightly hydrogenated TiO 2 could be attributed to the higher ratio of trapped holes (O − centers) and a lower recombination rate induced by the increase of surface defects, while the highly concentrated bulk defects in gray and black (overhydrogenated) TiO 2 acted as charge recombination centers, leading to worse photoactivity [57]. Huang's group has reported on the synthesis of a series of black TiO 2 nanomaterials by aluminum reduction [9,32,37,38,41,53]. The typical crystalline/amorphous core/shell structure was observed in almost all Al-reduced black TiO 2 [9,32,37,38,41], except for the black TiO 2 nanotubes [53].…”

“…Oxygen vacancies are undetectable in most white TiO 2 nanomaterials, while oxygen vacancy is considered to be one of the feature defects in most black TiO 2 nanomaterials. Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscope [37][38][39][40]52], Raman spectroscope [9,16,32,[53][54][55], and X-ray diffractometer [23,32,55] [30,33,37,41,52,55,57,59,60].…”