Photocatalytic Investigation of Aerosol-Assisted Atmospheric Pressure Plasma Deposited Hybrid TiO2 Containing Nanocomposite Coatings

Abstract

We report on the aerosol-assisted atmospheric-pressure plasma deposition onto a stainless-steel woven mesh of a thin nanocomposite coating based on TiO2 nanoparticles hosted in a hybrid organic–inorganic matrix, starting from nanoparticles dispersed in a mixture of hexamethyldisiloxane and isopropyl alcohol. The stainless-steel mesh was selected as an effective support for the possible future technological application of the coating for photocatalytically assisted water depollution. The prepared coatings were thoroughly investigated from the chemical and morphological points of view and were demonstrated to be photocatalytically active in the degradation of an organic molecule, used as a pollutant model, in water upon UV light irradiation. In order to optimize the photocatalytic performance, different approaches were investigated for the coating’s realization, namely (i) the control of the deposition time and (ii) the application of a postdeposition O2 plasma treatment on the pristine coatings. Both strategies were found to be able to increase the photocatalytic activity, and, remarkably, their combination resulted in a further enhancement of the photoactivity. Indeed, the proposed combined approach allowed a three-fold increase in the kinetic constant of the degradation reaction of the model dye methylene blue with respect to the pristine coating. Interestingly, the chemical and morphological characterizations of all the prepared coatings were able to account for the enhancement of the photocatalytic performance. Indeed, the presence of the TiO2 nanoparticles on the outmost surface of the film confirmed the accessibility of the photocatalytic sites in the nanocomposite and reasonably explained the enhanced photocatalytic performance. In addition, the sustained photoactivity (>5 cycles of use) of the nanocomposites was demonstrated.

Atmospheric Pressure Plasma Deposition of Hybrid Nanocomposite Coatings Containing TiO2 and Carbon-Based Nanomaterials

“…Such aggregates appear characterized by a more regular spheroidal shape in the case of ncTiO 2 _C 60 . Conversely, the CNM-free nanocomposite coating, ncTiO 2 , do not exhibit such features, as it can be observed in the SEM micrographs reported in Figure S2 , in agreement with what was previously reported [ 9 ]. Hence, such submicrometric cylindrical features can likely be ascribed to the presence of CNM in the coating; however, further investigations would be needed to account for the different morphology observed upon the addition of rGO or C 60 as fillers, respectively.…”

“…Indeed, the deposition of homogeneous films can be achieved in a one-step procedure, starting from a monomer or its solution, while nanocomposite coatings can be obtained from a suspension/solution of the nanofiller and the use of an auxiliary feed of the monomer as a gas or as an aerosol [ 8 ]. In particular, deposition onto different solid supports of nanocomposite coatings containing TiO 2 nanoparticles in an organic polymeric matrix has been recently described for addressing photocatalytic applications [ 9 ].…”