| In this study, because of the low separation efficiency of photo-electrons and holes that leads to the low rate of oxygen evolution and difficult to match the rate of hydrogen evolution in the "Double-Bed" splitting water system, modified rutile TiO2 was synthesised by being treated using semiconductor doping, semiconductor compounding and reducing atmosphere. The photocatalytic-activities for oxygen evolution were firstly compared in the "Double-Bed" splitting water system using rutile TiO2 catalysts compounded different semiconductors or the same semiconductor with different compounding concentration. Rutile TiO2 and 2% WO3-TiO2 were treated by reducing atmosphere and the photocatalytic activity of TiO2 and 2% WO3-TiO2 with oxygen vacancies were firstly investigated in the "Double-Bed" splitting water system. Quantum chemistry calculations for different oxygen vacancies content of TiO2 were carried out and the results can reasonablely explain experimental results.WO3 compounding can improve the rate of O2 evolution of the photodecomposition of water. It reaches to 151.8μmol·L-1·h-1 when the concentration of compounding WO3 is 2% which is the concentration of monolayer for WO3 on the surface of TiO2/Nb2O5. Besides, the concentration of the electron acceptor Fe3+ and the second calcination temperature also can effect the rate of O2 evolution. When the concentration of Fe3+ is 16·10-3mol·L-1 and the second calcination temperature is 600℃the maximum rate of O2 evolution of 2%WO3-TiO2/Nb2O5 photocatalyst is 191.7μmol·L-1·h-1.From the result of LRS, the concentration of monolayered WO3 on the surface of TiO2 is 2 mol%. The rate of O2 evolution for TiO2 compounded with WO3 as photocatalyst is larger than that of the TiO2 within 12 hours. With the increase of the quantity of loaded WO3, the rate of O2 evolution also increases. It reaches to the maximum rate of 420μmol·L-1·h-1 with the UV-light irradiation when the concentration of loaded WO3 is 2%. When the concentration of compounding WO3 is above 2.67%, the rate of O2 evolution decreased gradually. There is no response to visible light for WO3-TiO2. According to its transmitted spectrum, the band gap energy of WO3 is about 2.78eV by extrapolation. The concentration of monolayer for V2O5 on the surface of TiO2 is 8%. The maximum rate of O2 evolution is 110μmol·L-1·h-1 when the concentration of compounding V2O5 is 8% with the UV-light irradiation and 80μmol·L-1·h-1 with the visible light irradiation. According to its transmitted spectrum, the band gap energy of V2O5 is about 2.14eV by extrapolation and 3.08eV for rutile TiO2. As for Fe2O3- TiO2, there is no gas evolution with the UV-light or visible light irradiation. The FL spectrum and the rate of O2 evolution show that the photocatalytic activity of the catalyst is influenceed by several factors and the FL intensity is not the pacing one.Appropriate oxygen vacancies could obviously improve the photocatalytic activity of rutile TiO2 with minute quantity Ti3+ and hydroxyl group (OH). The maximum rate for O2 evolution of rutile TiO2 with oxygen vacancies was 222μmol·L-1·h-1. The theoretical calculation shows that oxygen vacancies can reduce the band-gap energy of rutile TiO2 and introduce middle energy level in its forbidden band.The maximum rate for O2 evolution of 2.0%WO3-TiO2 with oxygen vacancies is 803μmol·L-1·h-1 which matches the H2 evolution speed in "Double-Bed" water splitting.
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