Enhancement of photocatalytic activities of nitrogen-doped titanium dioxide by ambient plasma

Sustainable and Green Synthesis of Waste-Biomass-Derived Carbon Dots for Parallel and Semi-Quantitative Visual Detection of Cr(VI) and Fe3

Carbon dot (CD)-based multi-mode sensing has drawn much attention owing to its wider application range and higher availability compared with single-mode sensing. Herein, a simple and green methodology to construct a CD-based dual-mode fluorescent sensor from the waste biomass of flowers of wintersweet (FW-CDs) for parallel and semi-quantitative visual detection of Cr(VI) and Fe3+ was firstly reported. The FW-CD fluorescent probe had a high sensitivity to Cr(VI) and Fe3+ with wide ranges of linearity from 0.1 to 60 µM and 0.05 to 100 µM along with low detection limits (LOD) of 0.07 µM and 0.15 µM, respectively. Accordingly, the FW-CD-based dual-mode sensor had an excellent parallel sensing capacity toward Cr(VI) and Fe3+ with high selectivity and strong anti-interference capability by co-using dual-functional integration and dual-masking strategies. The developed parallel sensing platform was successfully applied to Cr(VI) and Fe3+ quantitative detection in real samples with high precision and good recovery. More importantly, a novel FW-CD-based fluorescent hydrogel sensor was fabricated and first applied in the parallel and semi-quantitative visual detection of Cr(VI) and ferrous ions in industrial effluent and iron supplements, further demonstrating the significant advantage of parallel and visual sensing strategies.

Titanium industrial residues surface modification towards its reuse as antimicrobial surfaces

In this study, a new material obtained from titanium ingots residue was coated with natural carotenoids having antibacterial properties. The waste is a no recycling titanium scrap from technological production process which was pressed and transformed into disks titanium samples. Through anodization and annealing procedures of the titanium disk, a nanostructured titanium dioxide surface with photocatalytic and antibacterial properties was successfully obtained. The titanium scrap impurities (V, Al, and N), unwanted for production process, have shown to improve electrochemical and semiconductor properties of the residue surfaces. The nanostructured titanium scrap surface was modified with two different carotenoids, torularhodin and β-carotene, to potentiate the antibacterial properties. The bactericidal tests were performed against Salmonella typhimurium and Escherichia coli, both Gram-negative. The best bactericidal effect is obtained for nanostructured titanium scrap disks immersed in torularhodin, with a percentage of growth inhibition around 60% against both tested bacteria. The results suggest that this low-cost waste material is suitable for efficient reuse as antibacterial surface after a few simple and inexpensive treatments.

Synthesis of N-Doped Magnetic WO3-x@Mesoporous Carbon Using a Diatom Template and Plasma Modification: Visible-Light-Driven Photocatalytic Activities

Synthesis of three-dimensional photocatalysts offers great potential for chemical conversion and hydrogen generation as appropriate solutions for environmental protection and energy shortage challenges. In this study, the magnetic WO_3-x@mesoporous carbon (M-WO_3-x@MC) was synthesized through the evaporation-induced self-assembly method applying diatom frustules as a natural template. Then, plasma modification was used to prepare the N-doped M-WO_3-x@MC (NM-WO_3-x@MC) with enhanced photocatalytic activity and durable performance. The WO_3-x was embedded in the conductive MC, which was also partially reduced by the carbon precursor within the heat-treatment procedure. The obtained M-WO_3-x@MC was treated by the plasma under an N₂ atmosphere for the production of the final photocatalyst containing both the N-doped WO_3-x and MC. As a result, the NM-WO_3-x@MC had larger surface area (208.4 m² g^-1), narrower band gap (2.3 eV), more visible light harvesting, and confined electron-hole pairs recombination. The H₂ generation rates of net WO₃ nanorods and NM-WO_3-x@MC nanocomposite were estimated as 532 and 2765 μmol g^-1 h^-1, respectively. Additionally, more than 90% of antibiotics (cephalexin, cefazolin and cephradine) degradation and 76% of total organic carbon elimination were obtained after 120 and 240 min of photocatalytic process under visible light irradiation. Eventually, more than eight intermediates were detected for each antibiotic degradation using the gas chromatography-mass spectrometer method, and based on the obtained results, the possible degradation pathways were suggested.

C-,N- and S-Doped TiO2 Photocatalysts: A Review

This article presents an overview of the reports on the doping of TiO2 with carbon, nitrogen, and sulfur, including single, co-, and tri-doping. A comparison of the properties of the photocatalysts synthesized from various precursors of TiO2 and C, N, or S dopants is summarized. Selected methods of synthesis of the non-metal doped TiO2 are also described. Furthermore, the influence of the preparation conditions on the doping mode (interstitial or substitutional) with reference to various types of the modified TiO2 is summarized. The mechanisms of photocatalysis for the different modes of the non-metal doping are also discussed. Moreover, selected applications of the non-metal doped TiO2 photocatalysts are shown, including the removal of organic compounds from water/wastewater, air purification, production of hydrogen, lithium storage, inactivation of bacteria, or carbon dioxide reduction.

Preparation and photocatalytic performance of silver-modified and nitrogen-doped TiO2 nanomaterials with oxygen vacancies

A modified hydrothermal method for the synthesis of TiO₂ material to achieve a more efficient visible light response.