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

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.

Effect of Structural Changes at Various Length Scales in SiVOC Ceramic Nanocomposites on Electrocatalytic Performance for the Oxygen Reduction Reaction

“…Silicon-based polymer-derived ceramics (PDCs) have proven to be stable under harsh chemical conditions. − Synthesizing nanocomposites by in situ crystallization of metallic compounds in a Si-based PDC matrix was extensively investigated for various applications such as photocatalysis, Li-ion batteries, and high-temperature applications. − Also, such ceramics were investigated for the hydrogen evolution reaction (HER) as well as the ORR. Molybdenum-modified SiC ceramics synthesized through this route resulted in the formation of nanocrystalline Mo 3+2 x Si 2 C 0.6 in the SiC matrix.…”

New insights into the electrochemical performance of precursor derived Si(Nb)OC composites as anode materials for batteries

“…17 The current literature shows that transition metal modied PDCs via precursor route improves their mechanical, functional, and electrical properties. [26][27][28][29][30][31][32] In an earlier study, titanium-modied SiOC (or Si(Ti)OC) was synthesized through pyrolysis of titanium butoxide-modied polymethylhydrosiloxane (PMHS) single source precursor and investigated as potential anode material for LIBs. 33 The aspyrolyzed Si(Ti)OC electrode demonstrates good rate capability due to its unique structure of amorphous SiOC matrix with graphene-like free carbon phase and uniformly distributed transition metal oxide crystals.…”

Macromonomers as a Novel Way to Investigate and Tailor Silicon-Oxycarbide-Based Materials Obtained from Polymeric Preceramic Precursors

“…As both the free-carbon content and its type can vary, silicon-oxycarbide-based black glass can be a semiconductor or insulator, and the addition of carbon forms, for example, can make the material conductive [6]. Such properties make silicon oxycarbide a promising material for protective coatings [7,8], electrodes in batteries [9], fuel cells [10], catalysis [11,12], or in medicine [13,14].…”

“…Materials 2021, 14, x FOR PEER REVIEW 2 of 17 protective coatings [7,8], electrodes in batteries [9], fuel cells [10], catalysis [11,12], or in medicine [13,14]. The synthesis of silicon-oxycarbide-based black glass is impossible with standard powder methods.…”