Some interesting properties of black hydrogen-treated TiO2 nanowires and their potential application in solar energy conversion

Abstract

Hydrogen treatment has been proposed as a simple and effective strategy to enhance the performance of TiO 2 nanostructures for applications such as photocatalysis and photoelectrochemical (PEC) water splitting. While some studies have suggested that the black color can be ascribed to surface disorder, other reports have suggested that it is caused by the "oxygen vacancy" states associated with Ti 3+ within the bandgap of the TiO 2 . The chemical nature and potential use of the bandgap states responsible for the black color of increased visible absorption is not yet well understood and subject of strong interest. Here we briefly review current understanding of the possible mechanisms behind the black color of hydrogen-treated TiO 2 nanowires and its relevance to photocatalysis and solar water splitting for hydrogen generation. One important conclusion to date is that while hydrogen treatment enhances photocurrent of TiO 2 with UV excitation, no noticeable photocurrent can be detected with visible light, which seems to be due to the very short lifetimes of the bandgap oxygen vacancy states arising from hydrogen treatment.black TiO 2 , photoelectrochemical water splitting, TiO 2 nanowires, hydrogen treatment, oxygen vacancy

Photocatalytic Overall Water Splitting by SrTiO3 with Surface Oxygen Vacancies

“…Herein, the photocurrent density of SrTiO 3 -C950 shows a slow decrease with the following cycles, which may be due to the destruction of surface oxygen vacancies under the presence of external electric fields during a photocurrent test. It is proposed that, besides the aforementioned two factors, the higher charge separation efficiency is ascribed to the temporary storage capacity of surface oxygen vacancies for photogenerated carriers [ 21 , 45 ]. Moreover, according to the previous reports, the formed surface oxygen vacancies and SrO species are proposed to be more favorable for the adsorption and decomposition of water molecules [ 30 ].…”

Sulfur Confined in Sub‐Nanometer‐Sized 2 D Graphene Interlayers and Its Electrochemical Behavior in Lithium–Sulfur Batteries

“…Increasing demands for high efficient energy storage techniques have triggered special interest in diverse energy storage devices and related electrode materials . Li−S batteries, which have extremely high energy density (up to 2600 Wh kg −1 ), have become a promising battery system and have received wide and intense attention during the past few years .…”

“…Increasingd emands for high efficient energy storaget echniques have triggered special interestindiverseenergy storage devices and related electrode materials. [1][2][3][4][5][6][7][8][9][10][11] LiÀSb atteries, which have extremelyh igh energy density (up to 2600 Wh kg À1 ), have become ap romising battery system and have received wide and intense attention during the past few years. [12][13][14][15][16][17][18][19] AlthoughL i ÀSb atteries present many advantages mainly in terms of high energy density,e nvironmental friendliness as well as cost-effectiveness, [20,21] severali ssues have hin-dered their commercial applications.…”

Angstrom Thick ZnO Passivation Layer to Improve the Photoelectrochemical Water Splitting Performance of a TiO2 Nanowire Photoanode: The Role of Deposition Temperature

“…From optical perspective, elemental doping using metal and non-metal particles 12 – 24 , hydrogen treatment 25 – 30 , semiconductor sensitization 31 – 37 , dye sensitization 38 – 45 , and plasmonic metal incorporation 46 – 54 are examples of the ideas on the development of PEC performance of the TiO 2 . As discussed above, the ultimate goal of these studies is further improvement in light absorption toward longer wavelengths as visible (Vis) and near infrared (NIR) regimes.…”