研究目的
The preparation of multifunctional titania-based photocatalysts with inherent capabilities for thermal co-activation and stabilisation of anatase polymorph, by designing the phase composition and microstructure of rutile-silicon carbide mixture.
研究成果
The research has demonstrated a potential alternative route towards efficient TiO2-based photocatalysts using conventional raw materials. The selected processing approach included a partial pre-reduction of titania by silicon carbide in inert argon atmosphere, intending to produce precursors capable of forming anatase in the oxidising conditions. This was followed by delicate oxidation under air conditions to produce TiO2, both in the form of rutile and anatase. The best-prepared material's activity, expressed in the apparent rate constant, was only ~1.6 times lower than the corresponding activity of the nanostructured industrial P25 photocatalyst possessing a 2–3 times larger surface area.
研究不足
The technical and application constraints of the experiments include the health aspects of the entire class of nanomaterials, especially in terms of long-time-exposure effects. Microscale platforms may also provide significant advantages in terms of photocatalyst recovery, but the nanosized TiO2 usually offers an improved performance over microscale particles.
1：Experimental Design and Method Selection:
The processing involved a conventional solid state route, including partial pre-reduction of rutile by SiC in inert Ar atmosphere, followed by post-oxidation in air. The impacts of processing conditions on the phase composition and photocatalytic activity were evaluated using Taguchi planning.
2：Sample Selection and Data Sources:
The precursor powders for the preparation of the target composite materials included titanium (IV) dioxide, rutile (TiO2, Alfa Aesar, Kandel, Germany) and silicon carbide, β-phase (SiC, Alfa Aesar, Kandel, Germany). These powders were mixed in a molar proportion of 1:1, and ball-milled with ethanol, using a nylon container with Tosoh tetragonal zirconia milling media, for 4 h at 50 rpm.
3：List of Experimental Equipment and Materials:
Titanium (IV) dioxide, rutile (TiO2, Alfa Aesar, Kandel, Germany), silicon carbide, β-phase (SiC, Alfa Aesar, Kandel, Germany), ethanol, nylon container, Tosoh tetragonal zirconia milling media.
4：Experimental Procedures and Operational Workflow:
After drying, the mixed powders were used for the preparation of ~10 mm-thick pellets by uniaxial pressing at ≈ 40 MPa during ~30 s. After compacting, the pellets were pre-reduced in Ar atmosphere and further post-oxidised in air to assess the possibility for the formation and maintaining various titania-based phases for improved photocatalytic activity.
5：Data Analysis Methods:
The XRD phase analysis was performed using a high-resolution diffractometer (Malvern PANalytical X’Pert, Worcestershire, United Kingdom) using Cu Kα (I = 1.540598 ?) radiation. The data acquisition was performed for 2Θ from 5 to 80°, with 2 and 1° slits and a 200 s step time. The quantitative content of the crystalline phases was obtained using the Rietveld refinement method (TOPAS Version 4.2, Bruker AXS, Karlsruhe, Germany).
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