Ultrafast Spray of Tio2 Self-Cleaning Films in Tubular Substrates

Currently, atmospheric pressure cold plasma has been proven to be an effective technique for preparing TiO
2
coating on planar substrates
¹
. However, few studies have focused on spraying TiO
2
on the interior of a tubular substrate. In this study, we developed an ultrafast process for spraying TiO
2
self -cleaning films inside tubular substrates using an atmospheric pressure air plasma jet generated by a dielectric barrier structu -re with hollow electrodes (HEDBS), and the total processing time was less than 20s. During the spraying process, using TiCl
4
as precursor and air as working gas, the HEDBS plasma jet was inserted into a substrate tube and moved under control. The as-sprayed materials were characterized by various methods, such as SEM, Raman and XRD. Additionally, the self-cleaning properties of the prepared thin TiO
2
films were in -vestigated using oleic acid and n-heptane as target pollutants. Importantly, SEM images showed that the TiO
2
particles were dispersed evenly in the tubular substrates, and the spraying rate was estimated as 5 μm/s. Furthermore, Raman and XRD pattern indicated the anatase structure of the HEDBS-spayed TiO
2
coating after heating for 9 min. Further results of the self cleaning test suggested that the proposed cost- and timesaving HEDBS approach with air working gas could provide a feasible way for synthesizing thin TiO
2
nanofilms.