Effect of Synthesis Conditions of Nitrogen and Platinum Co-Doped Titania Films on the Photocatalytic Performance under Simulated Solar Light

Abstract

Platinum and nitrogen co-doped titania films of different surface morphologies obtained via a sol-gel process have been tested for tetracycline hydrochloride photocatalytic decomposition under simulated solar light. Titania crystallization to anatase is shown by XRD for all films. A shift of the bandgap edge toward the visible region in absorption spectra and, consequently, a narrowing of the bandgap is observed for some films doped with nitrogen and/or exposed to UV pretreatment. The surface peculiarities of the samples are presented by an SEM and TEM investigation. The surface saturation by Pt and N with a homogeneous distribution of Pt ions on the surface as well as bulk as established by XPS and EDS data can be achieved with a certain synthesis procedure. The influence of the platinum content and of the pretreatment procedure on the state and atomic surface concentration of incorporated nitrogen and platinum is studied by XPS analysis: substitutional and interstitial nitrogen, non-metal containing fragments, Pt0, Pt2+ and Pt4+ ions. The photocatalytic activity of the films is ruled by the presence of Pt2+ ions and N rather than Pt0. The formation of the polycrystalline titania structure and Pt0 nanoparticles (NPs) is confirmed by TEM and electron diffraction images. The mechanism of primary photocatalytic processes is proposed.

Platinum-Decorated TiO2: One Step Fast Monometallic Impregnation and Plasma Effect on Nanoparticles

“…The shift to a lower binding energy of Ti 2P 3/2 detected for N-TiO 2−x /Pt can be caused by nitrogen doping, as shown in the N 1s XPS spectra (Figure 5b). This observation has been confirmed by other research groups who correlate the shift to a lower binding energy with substitutional and interstitial nitrogen atoms into the TiO 2 matrix [28].…”

Photoelectrochemical, photocatalytic and electrocatalytic behavior of titania films modified by nitrogen and platinum species

“…The decreased E g value (3.10 eV) and a shift of E fb potential for N-TiO 2 compared to TiO 2 , shown in Fig. 1, can be explained by the crystallization of the mixture of anatase and brookite (Ihnatiuk et al 2020) in the approximated composition of 23% and 77%, respectively. As the synthesis of pure crystalline brookite form (without anatase and rutile) is quite difficult, there are numerous uncertainties related to its bandgap as well as to the energy position of the conduction band (Di Paola et al 2013;Shibata et al 2004).…”

“…The synthesis procedures of the films and electrodes have been performed as described in detail in Ihnatiuk et al (2020). The samples used in photocatalytic experiments and photoelectrochemical investigations have been coated on glass slides and Ti sheets, respectively.…”

“…The films were calcinated at 450 °C for 20 min at the heating rate of 7 °C/min in the presence of air. The samples coded as Pt(N)-TiO 2_M1(M2)_UV were additionally UV treated before calcination (see details in (Ihnatiuk et al 2020).…”

“…Recently, we have reported (Ihnatiuk et al 2020) the effect of synthesis conditions on the surface Pt oxidation states formed in TiO 2 lattice that, in turn, change the optical, photocatalytic and morphological properties of the films. It was found that Pt 0 NPs (nanoparticles) are formed in the structure of the films as a result of the redox reaction occurring during sol ripening and calcination of the films at certain conditions.…”