Photocatalytic activity of pulsed laser deposited TiO2 thin films

Abstract

Nanostructured TiO 2 thin films were prepared by pulsed laser deposition (PLD) on indium doped tin oxide (ITO) substrates. Results from X-ray photoelectron spectroscopy (XPS) show that Ti 2p core level peaks shift toward the lower binding energy with decrease in the buffer gas pressure (O 2 :Ar = 1:1). This suggests that oxygen vacancies are created under insufficient oxygen conditions. Anatase to rutile ratio is also found to be system pressure dependent. Under deposition pressure of 750 mTorr only anatase phase was observed even at 1073 K substrate temperature which is much higher that the bulk anatase to rutile phase transformation temperature. The deposited TiO 2 thin films were fabricated as photoanodes for photoelectrochemical (PEC) studies. PEC measurements on TiO 2 photoanodes show that the flatband potential (V fb ) increases by 0.088 eV on absolute vacuum energy scale (AVS) with decrease in the deposition pressure, from 750 to 250 mTorr at 873K. The highest incident photon to current conversion efficiency [IPCE(λ)] of 2.5 to 6 % was obtained from the thin films prepared at substrate temperature of 873K.Combining the results from XPS and PEC studies, we conclude that the deposition pressure affects the concentration of the oxygen vacancies which changes the electronic structure of the TiO 2 . With reference to photoelectrochemical catalytic performance, our results suggest that it is possible to adjust the Fermi energy level and structure of TiO 2 thin

Effect of Annealing Temperature on the Optical Properties of TiO₂ Thin Films Prepared by Pulse Laser Deposition

“…The anatase phase is especially adequate for those applications due to its crystal structure and a higher band gap of 3.2 eV compared to the 3 eV in rutile. Anatase and rutile have properties of interest for sensing applications [5]. In principle, transition metal with proper oxidation state replace some of the Ti (IV) from lattice producing an impurity state that reduces the band gap of TiO 2 .…”

Synthesis and characterization of mixed phase anatase TiO2 and sodium-doped TiO2(B) thin films by low pressure chemical vapour deposition (LPCVD)

“…In the case of self-cleaning materials, TiO 2 thin films have been prepared by a wide range of deposition methods such as sol-gel, 8 sputtering, 9 pulsed laser deposition (PLD), 10 physical vapour deposition (PVD) 11 and chemical vapour deposition (CVD) 12 . CVD is a low-cost process, which is easy to set up and subsequently adjust; it permits a high degree of compatibility with a wide range of substrates and also has the potential for mass production.…”

Sol-Jel Yöntemiyle Hazırlanan TiO2 Filmlerin Optik ve Elektrokromik Özellikleri

“…TiO 2 ince filmler hazırlanırken RF saçtırma [20], ultrasonik sprey piroliz [21], kimyasal buhar depolama [22], darbeli lazer biriktirme [23], DC magnetron [24], sol-jel [25,26] gibi birçok ince film kaplama yöntemi kullanılmaktadır. Bu yöntemlerden biri olan sol-jel yöntemi, homojen yapı elde edilmesi, her aşamanın kontrol altında tutulabilmesi, basit cihazlar gerektirmesi ve düşük sıcaklıklarda uygulanabilir olması sebebiyle metal oksit kaplamalar hazırlamak için kullanışlı bir yöntemdir [27].…”