Nature 2008,452(7190):975–978.CrossRef Competing interests The authors declare that they have no competing interests. Authors’ contributions AI wrote GDC-0994 mw the manuscript. HA and AI designed the experiment and analyzed the data with support from MT. HA acquired the ARPES data with support from AI, MA, and HN. High-quality single-crystalline samples were grown by MI, KF, SI, and SU. All authors discussed the results and commented on the manuscript.
All authors read and approved the final manuscript.”
“Background Among various oxide semiconductor photocatalysts, TiO2 has been studied extensively and considered to be the most appropriate for applications in the environmental field because of its biological and chemical inertness, cost effectiveness, strong oxidizing power, and long-term stability against chemical corrosion and photocorrosion . The photocatalytic ability of TiO2 is strongly affected by morphologies, phase structures, macroscopic structures, and so on [2–10].
In addition, the surface property is a key factor influencing the photocatalytic activity . The surface density for the 001 facets has been demonstrated to be higher than that for other facets with undercoordinated Ti atoms . The exposed 001 facets of anatase TiO2 have been proven to possess high surface energy, which induces high reactivity [12, 13]. Therefore, photocatalysts with higher reactivity can be obtained by controlling the exposed crystal facets of TiO2. Moreover, to improve the photocatalytic BX-795 in vitro activity of titania, reducing the band gap has been proven as a valid approach. An effective way to red shift the absorption edge can be achieved by doping one kind of element, such as F, Nb, and Mn [15–18]. After doping, Ti3+ states in TiO2 increase effectively. The existence of Ti3+ plays an important role on the enhancement of the photocatalytic activity . Thus, the use of codoping by two or more elements is reported to result in a significant improvement for increasing the photocatalytic activity, such as Nb and N [19, 20], Zr and Y , and F, B, and Si . In our previous work, titania micron
beads codoped with Nb and F were synthesized and used in DSSCs with beneficial result . In this paper, the Nb, F-codoped TiO2 hollow spheres (NFTSs) were synthesized via a facile hydrothermal process using niobium oxide and hydrofluoric Gemcitabine supplier acid as codoping source. The phase structure, morphology, chemical composition, band gap energy, and photocatalytic activity of the obtained product were investigated. Methods Preparation of NFTSs All chemicals, including tetrabutyl titanate, niobium oxide (Nb2O5) powder, hydrofluoric acid, and lactic acid, were of analytical grade and used as received without further purification. Nb2O5 was dissolved using hydrofluoric acid to obtain a clear and transparent solution. The Ti precursor was prepared using tetrabutyl PF299 cost titanate chelated with lactic acid.