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. 2018 Mar 1;11(3):362.
doi: 10.3390/ma11030362.

Novel Precursor-Derived Meso-/Macroporous TiO₂/SiOC Nanocomposites With Highly Stable Anatase Nanophase Providing Visible Light Photocatalytic Activity and Superior Adsorption of Organic Dyes

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Free PMC article

Novel Precursor-Derived Meso-/Macroporous TiO₂/SiOC Nanocomposites With Highly Stable Anatase Nanophase Providing Visible Light Photocatalytic Activity and Superior Adsorption of Organic Dyes

Eranezhuth Wasan Awin et al. Materials (Basel). .
Free PMC article

Abstract

Titania (TiO₂) is considered to have immense potential as a photocatalyst, the anatase phase in particular. There have been numerous attempts to push the limits of its catalytic activity to higher wavelengths to harness the visible electromagnetic radiation. Most of the investigations till date have been restricted to fine-tuning the bandgap by doping, control of defect chemistry at the surface and several to first principle simulations either with limited success or success at the cost of complexities in processing. Here, we report a simple and elegant way of preparing ceramics through precursor chemistry which involves synthesis of macroporous and mesoporous nanocomposites with in situ formation of TiO₂ nanocrystals into a robust and protecting SiOC matrix. The in situ nanoscaled TiO₂ is anatase of size 9-10 nm, which is uniformly distributed in an amorphous SiOC matrix forming a new generation of nanocomposites that combine the robustness, structural stability and durability of the SiOC matrix while achieving nanoscaled TiO₂ functionalities. The stabilization of the anatase phase even at temperature as high as 1200 °C was evident. With an average pore size of 6.8 nm, surface area of 129 m²/g (BET) and pore volume of 0.22 cm³/g (BET), mesoporosity was achieved in the nanocomposites. The composites exhibited visible light photocatalytic activity, which is attributed to the Ti-O-C/TiC bonds resulting in the reduction of band gap by 0.2 to 0.9 eV. Furthermore, the heterojunction formed between the amorphous SiOC and crystalline TiO₂ is also expected to minimize the recombination rate of electron-hole pair, making these novel nanocomposites based on TiO₂ extremely active in visible wavelength regime.

Keywords: adsorption; photocatalysis; precursor derived ceramics; silicon oxycarbide.

Conflict of interest statement

There are no conflicts to declare.

Figures

Figure 1
Figure 1
Schematic diagram of the general process for the synthesis of macroporous TiO2/SiOC nanocomposite.
Figure 2
Figure 2
Schematic diagram illustrating the generalized process for the synthesis of mesoporous TiO2/SiOC nanocomposite.
Figure 3
Figure 3
XRD of macroporous and mesoporous nanocomposites revealing the presence of anatase phase in an amorphous SiOC matrix (JCPDS card No. 20-2242).
Figure 4
Figure 4
Raman spectra (a) of the samples revealing the anatase phase of TiO2 in macroporous and mesoporous nanocomposites (b) exemplifying the shift in peak and (c) revealing the presence of free carbon.
Figure 5
Figure 5
(a) SEM micrograph revealing the foamy nature of the macroporous sample; (b) corresponding EDS analysis; (c) Higher magnification micrograph, inset: BET surface area plot; (d) micrograph of mesoporous sample revealing disordered mesoporous structure.
Figure 6
Figure 6
(a,c) TEM micrographs of macroporous and mesoporous nanocomposites revealing the well dispersed TiO2 nanoparticles in an amorphous SiOC matrix, respectively; (b,d) lattice fringes confirming the presence of anatase phase in macroporous and mesoporous nanocomposites, respectively.
Figure 7
Figure 7
Nitrogen adsorption-desorption curve of the mesoporous sample at −196 °C (inset: Pore size distribution curve).
Figure 8
Figure 8
Pore size distribution of macroporous nanocomposites by mercury intrusion porosimetry.
Figure 9
Figure 9
(a) Time dependent UV-vis absorption spectra of macroporous nanocomposite under visible light (inset: Photograph revealing the decolorization of MB); (b) kinetic curves of the degradation of MB by macroporous nanocomposite.
Figure 10
Figure 10
(a) UV-vis absorption spectra for 0.03 mM MB with 50 mg of mesoporous nanocomposite; inset: photograph revealing the decolorization of MB; (b) UV-vis absorption spectra for 0.03 mM MB with 25 mg of mesoporous nanocomposite; (c) pseudo first-order kinetics model; (d) pseudo second-order kinetics model; (e) intra particle-diffusion kinetic model.
Figure 11
Figure 11
(a) UV-vis absorption spectra for 0.06 mM (with 50 mg of mesoporous nanocomposite (inset: photograph revealing the decolorization of MB); (b) kinetic analysis of the degradation of MB by mesoporous nanocomposite.
Figure 12
Figure 12
(a) UV-vis DRS spectra; (b) Tau plot: Namely (αhν)1/2 vs. hν of macro/mesoporous nanocomposites and commercial TiO2.
Figure 13
Figure 13
FTIR transmittance spectra of TiO2/SiOC nanocomposite indicating the bonding characteristics.
Figure 14
Figure 14
XPS peak deconvolution of C(1s) and Ti(2p): (a,b) in macroporous and (c,d) mesoporous materials.
Figure 15
Figure 15
Schematic representation of band gap reduction mechanism and degradation process.
Figure 16
Figure 16
Schematic diagram of the heterojunction formation between TiO2 and SiOC.

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References

    1. Soraru G.D., Andrea G.D., Glisenti A. XPS Characterization of Gel-Derived Silicon Oxycarbide Glasses. Mater. Lett. 1996;27:l–5. doi: 10.1016/0167-577X(95)00245-6. - DOI
    1. Du P., Wang X., Lin I.-K., Zhang X. Effects of Composition and Thermal Annealing on the Mechanical Properties of Silicon Oxycarbide Films. Sens. Actuators A Phys. 2012;176:90–98. doi: 10.1016/j.sna.2012.01.002. - DOI
    1. Sorarù G.D., Pederiva L., Latournerie J., Raj R. Pyrolysis Kinetics for the Conversion of a Polymer into an Amorphous Silicon Oxycarbide Ceramic. J. Am. Ceram. Soc. 2002;85:2181–2187. doi: 10.1111/j.1151-2916.2002.tb00432.x. - DOI
    1. Xu T., Ma Q., Chen Z. High-Temperature Behavior of Silicon Oxycarbide Glasses in Air Environment. Ceram. Int. 2011;37:2555–2559. doi: 10.1016/j.ceramint.2011.03.053. - DOI
    1. Narisawa M., Ryu’ichi S., Ken’ichiro K. Evaluation of Oxidation Resistance of Thin Continuous Silicon Oxycarbide Fiber Derived from Silicone Resin with Low Carbon Content. J. Mater. Sci. 2010;45:5642–5648. doi: 10.1007/s10853-010-4629-7. - DOI
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