Preparation of hydrogen, fluorine and chlorine doped and co-doped titanium dioxide photocatalysts: a theoretical and experimental approach

Abstract

Titanium dioxide (TiO2) has a strong photocatalytic activity in the ultra-violet part of the spectrum combined with excellent chemical stability and abundance. However, its photocatalytic efficiency is prohibited by limited absorption within the visible range derived from its wide band gap value and the presence of charge trapping states located at the band edges, which act as electron–hole recombination centers. Herein, we modify the band gap and improve the optical properties of TiO2 via co-doping with hydrogen and halogen. The present density functional theory (DFT) calculations indicate that hydrogen is incorporated in interstitial sites while fluorine and chlorine can be inserted both as interstitial and oxygen substitutional defects. To investigate the synergy of dopants in TiO2 experimental characterization techniques such as Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray and ultra-violet photoelectron spectroscopy (XPS/UPS), UV–Vis absorption and scanning electron microscopy (SEM) measurements, have been conducted. The observations suggest that the oxide’s band gap is reduced upon halogen doping, particularly for chlorine, making this material promising for energy harvesting devices. The studies on hydrogen production ability of these materials support the enhanced hydrogen production rates for chlorine doped (Cl:TiO2) and hydrogenated (H:TiO2) oxides compared to the pristine TiO2 reference.

Impact of boron and indium doping on the structural, electronic and optical properties of SnO2

“…The bandgap is seen to increase to the value of 3.72 eV. As it is discussed in previous studies, the formation of energy states in the middle of the bandgap is highly beneficial for photocatalytic applications, but still, they can be a crucial disadvantage for PV and LED devices as they work as “traps” which reduce the device photocurrent and the photogenerated charge carriers 30 , 31 . Although B i :SnO 2 has not been examined theoretically, Zhi et al .…”

Adsorption and Mechanism of Glycine on the Anatase with Exposed (001) and (101) Facets

“…3.1. Synthesis of Anatase (TiO2) with Exposed (001) Facets and Characterization of the S Figure 1 shows the XRD spectra of anatase (TiO2) with two different crysta The dominant planes of anatase (TiO2) are the (101), (001), (010), and (100) planes, o the (101) facets is the most common [41]. The two kinds of anatase (TiO2) were co with the standard PDF cards in the Jade 6.0 search database (JCPDS No.…”

Synthesis and Characterization of Fe2+ Ion-Exchanged TiO2 Materials and Their Supported V2O5 Catalysts for a Great Depression of the Formation of N2O in the Selective Reduction of NO by NH3

“…Based on the textual properties according to the surface hydroxylation and sublimation temperature, we think that their changes are associated not only with the surface protonation of TiO 2 , but also gaseous HCl that has been generated during the solid-state reaction between the Fe precursor (FeCl 2 ·4H 2 O) and surface OH groups on the HT as for that between FeCl 3 and H-ZSM-5 . Although TiO 2 after drying can be protonated to Ti–H and Ti–OH, this would be predominantly formed since the surface of TiO 2 dried at 110 °C was hydroxylated in an aqueous solution of NH 4 OH at ambient conditions in this study. Introduction of such Ti–OH species onto the pristine TiO 2 surface could result in a small decrease in S BET and V t , as seen for the HT.…”