Uniformity, Structure, and Photocatalytic Activity of TiO₂ Films Deposited by Atmospheric‐Pressure Linear Cold Plasma

Abstract

Atmospheric-pressure (AP) linear cold plasma CVD is employed to deposit TiO 2 photocatalytic films uniformly on a moving substrate. The in-plane and in-depth uniformities of the as-deposited TiO 2 films are investigated by scanning electron microscopy (SEM) and UV-vis spectroscopy. The chemical binding states and compositions of the as-deposited TiO 2 films are characterized by X-ray photoelectron spectroscopy (XPS). Raman, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectra prove the structures of the as-deposited and calcined TiO 2 films are mainly hydro-oxygenated amorphous (a-TiO x :OH), and exclusively anatase, respectively. The photocatalytic activity of the as-deposited and calcined TiO 2 films is evaluated in a continuous flow reactor for HCHO removal with simulated air. The activity of the as-deposited TiO 2 films increases with film thickness, leveling off at about 780 nm. The activity of the as-deposited TiO 2 film is lower than that of the calcined one.

Gas–Liquid Cold Plasma for Synthesizing Copper Hydroxide Nitrate Nanosheets with High Adsorption Capacity

“…This may be due to the fast gas–liquid plasma preparation process (just 12 min), which is not beneficial to the formation of compact materials. This is consistent with previous work for plasma‐enhanced chemical vapor deposition of TiO 2 films …”

“…The presence of NO 3 − ions between copper hydroxide layers was evidenced by the symmetric and asymmetric stretching modes of NO 3 − at 1417 cm −1 and 1352 cm −1 , respectively. The peaks at 3445 cm −1 , 3417 cm −1 , and 1616 cm −1 correspond to the stretching vibration of the hydroxyl group of water and hydrogen‐bound hydroxyl groups, and the bending mode of water molecules . Furthermore, no peaks corresponding to other copper impurities were detected.…”

Facile and Fast Deposition of Amorphous TiO2 Film under Atmospheric Pressure and at Room Temperature, and its High Photocatalytic Activity under UV‐C Light

“…Based upon the assumption of a pseudo‐first‐order reaction, the apparent rate constant ( k ) of photocatalytic complete oxidation of HCHO was obtained, , where and are the inlet and outlet concentrations of HCHO, respectively, and is the outlet concentration of CO 2 . Thereby, the apparent rate constants of the TiO 2 /glass and TiO 2 /PET films are both 2.2 s −1 , which is larger than those reported in our previous papers . The high photocatalytic activity of the as‐deposited TiO 2 films derives from the following three reasons.…”

“…The crystallinity of the film was investigated by XRD at scanning speeds of 4.0° min −1 (XRD‐6000, Shimadzu) and 0.2° min −1 (Empyrean, PANalytical). Raman spectra of the film were obtained on a DL‐02 Raman spectrometer (home‐made) . The functional group composition of the films was analyzed by a FTIR spectroscopy (Tensor 27, Bruker) equipped with an MCT detector in its transmittance mode.…”

“…To achieve a low‐temperature CVD process, the CVD reaction should occur at such a temperature. With the assistance of plasma activation for gaseous reactants, plasma CVD is an effective method for preparing TiO 2 films at low temperatures . Another strategy is to select a suitable CVD reaction which can start spontaneously at low temperatures.…”