Pulsed Laser-Deposited TiO2-based Films: Synthesis, Electronic Structure and Photocatalytic Activity

Abstract

Abstract"ctive under visible light, photocatalysts based on doped titania were obtained via pulsed laser deposition PLD method. To find out the crystalline structure, optical properties, and electronic structure, the following techniques such as X-ray diffraction, electronic spectroscopy, electrical conductivity measurements, and X-ray photoelectron spectroscopy XPS are used. Photocatalytic activity is monitored by applying the photoreduction of dichromate ions under UV and visible light. The influence of zirconium ions and its content and synthesis conditions on the efficiency of nitrogen incorporation into titania structure that, in turn, determines the electronic structure and photocatalytic ability of the semiconductive materials are discussed. " substitutional nitrogen Ti N rather than an interstitial one Ti O N is mainly responsible for the observed photoactivity. It is pointed that substitutional nitrogen is responsible for bandgap narrowing or formation of intragap localized states within semiconductor bandgap. The bandgap energy values are sharply decreased, while the relative intensity of substitutional nitrogen XPS peaks is increased. Pulsed laser synthesis of TiO films in N /CH atmosphere not only leads to nitrogen incorporation but also to the formation of defects including oxygen vacancies and Ti + states which are all contributing to light absorption. "n appropriate ratio of gas mixture, optimum zirconia content, suitable pressure, and temperature during synthesis was found for the synthesis of highly active semiconductive films. The highest photocatalytic conversion yields are obtained for nitrogen-doped % ZrO /TiO synthesized in N CH = at Pa and at °C under both UV and visible light.

Non-porous Iron Titanate Thin Films Doped with Nitrogen: Optical, Structural, and Photocatalytic Properties

“…XPS values within 396–397 eV are signed to the formation of the bond corresponded to N–Ti–N bonds [27, 28] and O-Ti-N [28, 29], respectively. N1s binding energies of 399.1 and 400.5 eV measured for modified by urea commercially available TiO 2 powder were assigned to carbon nitrides (399–400 eV, C = N-C), graphite-like phases (400.6 eV, N-Csp 2 ) and to polycyanogen (399.0, 400.5 eV, (−C = N−) x ) [30].…”

“…Binding energy positions at 397.2, 398.1, and 399.8 eV provide the assumption about an interstitial nitrogen incorporation with the trace of remained nitrogen-carbon bonds. Analyzing all our previous investigations connected with the nitrogen and metal co-doped titania films, it is concluded that interstitial nitrogen incorporation occurred when urea was applied as the doping agent [31, 32], On the other hand, the substitutional nitrogen incorporation performed by Pulse laser deposition method is responsible for the improvement of photocatalytic performance for nitrogen and zirconia co-doped titania films [28]. …”

The Impact of Side-Selective Laser Tailoring of Titania Nanotubes on Changes in Photoelectrocatalytic Activity

“…Consequently, as the electrons leave the thin, metal oxyhydroxide layer, it depletes, gaining a more positive charge relative to the titania, which in turn allows for a much easier adsorption of the oxygen from the OH − groups ( Figure 14 ). Moreover, laser modification can result in the formation of additional oxygen vacancies within titania, leading to an elevated potential difference in the depleted micro p-n junction [ 69 , 70 ].…”

Surface Topography of Si/TiO2 Stacked Layers on Silicon Substrate Deposited by KrF Excimer Laser Ablation

“…A different approach in creating the buried oxide layers can be provided by a versatile technique, which is pulsed laser deposition (PLD) [9][10][11][12]. This study focuses on the preparation and characterization of silicon-oxide-silicon structures obtained as stacked thin films deposited on silicon wafer by PLD.…”