Facile preparation of nitrogen-doped nanostructured titania microspheres by a new method of Thermally Assisted Reactions in Aqueous Sprays

Abstract

N-doped nanocrystalline titania microspheres with controlled visible light absorption were obtained by a new route utilizing a heterogeneous hydrolysis of TiCl 4 vapor with reactive droplets of aqueous aerosols, followed by instant calcination of the products in a preheated flow reactor. Thus prepared separate microspheres with a diameter of 0.5-3 microns were found to consist of anatase or rutile nanocrystals, depending on the parameters of the synthesis. Doped titania samples with different nitrogen contents were synthesized using water solutions with various concentrations of urea in the hydrolyzing aerosols. N À species were found to be a major form of nitrogen impurity. A plausible mechanism for the incorporation of nitrogen into titanium dioxide was proposed. The photocatalytic activity of the obtained powders under UV-visible or visible illumination was found to have a complex dependence on the calcination temperature and the titania doping level. ExperimentalThe experimental setup consists of two main parts, the rst for vaporized TiCl 4 hydrolysis with a water-based aerosol, and the

Unveiling point defects in titania mesocrystals: a combined EPR and XPS study

“…11 was reliably demonstrated in our previous papers. [19][20][21] The illumination (245-900 nm) of the samples did not lead to the appearance of any EPR signals. Yet, another reason existed for the absence of signals in the EPR spectrum.…”

Extraordinary sensitizing effect of co-doped carbon nanodots derived from mate herb: Application to enhanced photocatalytic degradation of chlorinated wastewater compounds under visible light

“…Therefore, narrowing down the band-gap of TiO 2 to increase the visible-light absorption response is an often-used strategy to improve the photocatalyst performance 13,14 . Among the procedures employed are: (i) chemical modifications with light elements such as carbon, nitrogen, boron or sulfur to shift the absorption toward the visible range by creating intermediate energy states that narrow the band gap 13,14 ; (ii) addition of plasmonic noble metals that boost absorption in the visible-NIR range due to their surface plasmon resonance (SPR) band [15][16][17][18][19][20][21] ; (iii) use of sensitizers such as organic dyes and/or narrow band-gap quantum dots that absorb visible light and inject electrons into the conduction band of TiO 2 to suppress the recombination rate of electron-hole pairs as in the case of quantum dot sensitized solar cells (QDSSCs) 22-25 . This work investigates the use of carbon nanodots (CNDs) in TiO 2 to create a visiblelight photo-catalyst that not only is efficient for solar-driven pollution abatement, but also inexpensive, durable and environmentally-friendly [26][27][28][29][30][31][32][33][34] . Carbon dots are luminescent nanomaterials characterized by their broad absorption spectra, resistance to photo-bleaching and low toxicity 30,31,[33][34][35][36][37][38][39] .…”

Hybridising nitrogen doped titania with kaolinite: A feasible catalyst for a semi-continuous photo-degradation reactor system

“…The question is whether it is possible to incorporate N-doping and catalyst immobilization methods together to hybrid N-doped TiO 2 with functionalised carriers or supports [15]. We will synthesize a new composite photocatalyst of N-doped TiO 2 hybridized with kaolinite (NTK).…”