Photocatalytic Anatase TiO₂ Thin Films on Polymer Optical Fiber Using Atmospheric-Pressure Plasma

Abstract

Due to the undeniable industrial advantages of low-temperature atmospheric-pressure plasma processes, such as low cost, low temperature, easy implementation, and in-line process capabilities, they have become the most promising next-generation candidate system for replacing thermal chemical vapor deposition or wet chemical processes for the deposition of functional coatings. In the work detailed in this article, photocatalytic anatase TiO thin films were deposited at a low temperature on polymer optical fibers using an atmospheric-pressure plasma process. This method overcomes the challenge of forming crystalline transition metal oxide coatings on polymer substrates by using a dry and up-scalable method. The careful selection of the plasma source and the titanium precursor, i.e., titanium ethoxide with a short alkoxy group, allowed the deposition of well-adherent, dense, and crystalline TiO coatings at low substrate temperature. Raman and XRD investigations showed that the addition of oxygen to the precursor's carrier gas resulted in a further increase of the film's crystallinity. Furthermore, the films deposited in the presence of oxygen exhibited a better photocatalytic activity toward methylene blue degradation assumedly due to their higher amount of photoactive {101} facets.

Insights into the Role of Plasma in Atmospheric Pressure Chemical Vapor Deposition of Titanium Dioxide Thin Films

“…2 . The Ti2p core level spectra shows two components, Ti2p 3/2 and Ti2p 1/2 , spaced 5.7 eV apart at 459 eV and 464.7 eV respectively, corresponding to Ti 4+ state in TiO 2 as reported in the literature 3 . The O1s peak comprises three contributions at 530.6, 532.1 and 533.3 eV.…”

“…Nowadays, titanium dioxide (TiO 2 ) is being intensively studied notably because of its chemical stability, optical and photocatalytic properties 1 – 8 . TiO 2 , especially under thin film form, was synthesized and demonstrated potential for applications such as anti-reflection coatings 1 , 2 , photocatalytic coatings for air and water purification 3 , 4 , self-cleaning surfaces 5 , anti-bacterial coatings 6 , 7 and anti-corrosion thin films 8 . Various TiO 2 thin film deposition methods have been studied and employed in literature 9 – 15 .…”

“…In order to reach high deposition rate and to form anatase at room temperature, Plasma Enhanced CVD methods are investigated in literature. Indeed, Atmospheric-Pressure Plasma Enhanced Chemical Vapor Deposition (AP-PECVD) has been reported as a promising method for TiO 2 thin films deposition thanks to several advantages such as simple in-line implementation in roll-to-roll systems because of no vacuum requirement, high deposition rate and low temperature processing 3 , 15 , 21 – 31 . In order to avoid potentially dangerous precursors such as titanium tetrachloride TiCl 4 22 , 23 , 31 , titanium-containing precursors such as titanium tetraisopropoxide (TTIP) 21 , 30 , titanium ethoxide (TEOT) 3 , or titanium bis-(acetylacetonate) diisopropoxide (TIPO) 29 are currently favored.…”

Atmospheric plasma oxidative polymerization of ethylene dioxythiophene (EDOT) for the large‐scale preparation of highly transparent conducting thin films

“…Plasma‐enhanced chemical vapor deposition (PECVD) processes have been shown as excellent alternatives for the formation of a wide variety of thin films at both low temperature and atmospheric pressure (AP) . In addition, plasma, which is composed of a wide range of reactive species, including electrons, ions, electronically excited atoms and molecules, radicals and photons, allow the formation of materials that might be difficult to obtain from other technics .…”

Room‐Temperature Plasma‐Assisted Inkjet Printing of Highly Conductive Silver on Paper

“…In many chemical reactions, plasmas provide an alternative to thermal heating, allowing the deposition of a wide range of materials at much lower substrate temperature than conventional CVD . The most common examples being the atmospheric‐plasma‐enhanced (AP‐PE)CVD of SiO 2 thin films at room temperature or the significantly lower temperatures observed for the AP‐PECVD of anatase TiO 2 layers . In recent times, several groups have proposed the use of low‐pressure plasmas to produce conductive silver on polymer or glass substrates from NPs and MOD inks .…”