Excellent hydrogen evolution by a multi approach via structure–property tailoring of titania

Abstract

Titania as a doped and coupled semiconductor with Fe and Fe2O3, respectively, allows favorable alignment of band edges for remarkable hydrogen evolution.

Insight into the Fabrication and Characterization of Novel Heterojunctions of Fe2O3 and V2O5 with TiO2 and Graphene Oxide for Enhanced Photocatalytic Hydrogen Evolution: A Comparison Study

“…All of the PL spectra contain sharp narrow peaks instead of broad ones, suggesting the existence of various sub energy levels and a multiband gap within the system due to the presence of midband formation by Fe 3+ by the incorporation of Fe onto the TiO 2 matrix in g-FTMO, which is evident from the PL emission peaks around 462 nm. The presence of surface defects can be authenticated by emissions at 390, 413, and 434 nm due to recombination of trapped charge carriers . Thus, these vacancies, lattice defects, and midbands trap the electrons and later detrap them, facilitating electron migration to active sites and enhancing the HER, which is in good agreement with the UV–vis DRS results.…”

Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatment

“…Therefore, Fe 3+ and Co 2+ ions substitute Ti 4+ ions in TiO 2 matrix and cause a change in the band gap by forming their mid gap energy levels in the respective samples along with the formation of Ti 3+ and oxygen vacancies. The electronic transition from valance band to dopant level and then from dopant level to conduction band, and/or from valance band to oxygen level and then form oxygen level to Ti 3+ level/dopant level effectively cause a red shift in the absorption edge, showing reduced band gap 46 47 48 . In many cases, the localized level of t 2g state of the doping element even lies in the middle of band gap (in case of, Cr, Mn or Fe as the doping materials), and at the top of the valance band (when Co is used as a dopant) 49 .…”

Photo-active float for field water disinfection

“…A lower fluorescence emission intensity implies delay in the electron-hole recombination rate and high availability of the excitons for the photocatalytic reaction. 19 The graph shows a decrease in emission for NFTiO 2 nanoparticles in comparison with TiO 2 , indicating reduced recombination of e − /h + in doped TiO 2 . Titanium dioxide shows a broad and featureless emis- ), which further disproportionately form more HO • radicals 39 and holes in the valence band to react with H 2 O or hydroxide ions adsorbed on the surface to produce reactive hydroxyl radicals (OH • ).…”

“…[14][15][16] However, recently several modifications have been made to extend the light absorption capability of TiO 2 into the visible light region by coupling with a narrow band gap semiconductor, 17,18 doping with transition metals (Fe, Co, Ag, Cr and Mo), 19 codoping with two or more foreign ions, surface sensitization by organic dyes or metal complexes, surface fluorination, addition of a sacrificial agent (SA), different preparation techniques 20 and noble metal deposition which induces a substantial influence in modifying the electronic band structure and construction of favorable surface structure resulting in higher visible light absorption. 19,[21][22][23][24] Introduction of anionic dopants, especially nitrogen, to TiO 2 makes it possible to achieve band gap narrowing. 25 Doping of two types of nonmetal atoms such as C and N atoms, S and N atoms, B and N atoms, and F and N atoms shows more efficiency in contrast to a single nonmetal dopant.…”