Enhanced Photophysical Properties of Nanopatterned Titania Nanodots/Nanowires upon Hybridization with Silica via Block Copolymer Templated Sol-Gel Process

Abstract

Abstract:We fabricated titanium dioxide (TiO 2 )-silica (SiO 2 ) nanocomposite structures with controlled morphology by a simple synthetic approach using cooperative sol-gel chemistry and block copolymer (BCP) self-assembly. Mixed TiO 2 -SiO 2 sol-gel precursors were blended with amphiphilic poly(styrene-block-ethylene oxide) (PS-b-PEO) BCPs where the precursors were selectively incorporated into the hydrophilic PEO domains. Changing the volumetric ratio of TiO 2 -SiO 2 sol-gel precursor from 5% to 20%, a stepwise structural inversion occurred from nanodot arrays to discrete nanowires. Template free hybrid inorganic nanostructures were produced after the removal of PS-b-PEO by irradiation of UV light. The morphological evolution and photophysical properties were investigated by microscopic studies, UV-visible absorption and photocatalytic properties. OPEN ACCESSPolymers 2010, 2 491

Laser oxidative pyrolysis synthesis and annealing of TiO2 nanoparticles embedded in carbon–silica shells/matrix

“…The intense peak centered at 1095 cm −1 with his shoulder at 1227 cm −1 , found only for silica-containing powders was also reported at 1065 and 1200 cm −1 in [1] and attributed to Si O Si vibrations. The small peak visible in the same powders spectra centered around 940 cm −1 was considered an indication of the chemical connection between titania and silica, being reported and ascribed to Ti O Si vibrations [2,4,38]. Also, at 955 cm −1 the presence of Si OH stretching vibrations corresponding band was also reported in [1], whereas the same Si OH attributed peak was found at 921 cm −1 from SiO x films prepared by plasma CVD [40].…”

“…[2][3][4][5], all the resulted raw crystalline nanoparticles (including those from the TLOP 01 reference sample without silica) are surrounded by a more or less thick disordered shell/coating. In order to explain their formation, one must take into account the composition of the reaction mixture and the particularities of the laser pyrolysis technique.…”

“…Benefiting from the specific advantages of both components: semiconductive behavior and crystallinity from TiO 2 and porous, protective characteristic associated with the hydrophilicity and thermal resistance of SiO 2 , the titania-silica (nano)composites are a representative class of such materials. Sol-gel is the most used technique for their fabrication, allowing the synthesis of materials with very different morphologies such as aerogels [1] or nanopatterned nanodots/nanowires [2], having as targeted application the performant photocatalytic oxidation of various organic molecules. Moreover, silica-titania material was found to able to photodecompose the water (accelerated by RuS 2 doping) with H 2 and O 2 generation under UV light [3].…”

“…The gas-phase methods starting from various Ti and Si containing vaporized/sprayed precursors allow the synthesis of TiO 2 /SiO 2 films and powders in a continuous mode and much faster than in the sol-gel methods. Flame combustion is the most used gas-phase method and was employed for the obtaining of TiO 2 doped SiO 2 films for waveguide applications (from titanium tetraisopropoxide (TTIP) and [(CH 3 ) 2 SiO] 4 in a O 2 /H 2 flame) [8], TiO 2 @SiO 2 core-shell composite nanoparticles (from TiCl 4 and SiCl 4 using N 2 -shielded oxy-hydrogen flame and a multitubular injector) [9], column-shaped TiO 2 nanoparticles/fibers deposed on glass (from TTIP, tetraethoxysilane (TEOS) and a liquefied petroleum gas (LPG) -air/O 2 /N 2 combustible mixture) [10] and also binary SiO 2 /TiO 2 mixed oxide and composite nanoparticles from N 2 -diluted TTIP [11] or TiCl 4 [12] and HMDSO (or also SiCl 4 or SiBr 4 [13]) in an O 2 /N 2 /CH 4 flame at atmospheric pressure.…”

Organoacid‐Decorated NiFe2O4 Nanoparticles: An Efficient Catalyst for Green Synthesis of 2H‐Indazolo[2, 1‐b]phthalazine‐Triones and Pyrimido[1,2‐a]benzimidazoles

“…The presence of the anchored alkyl groups is confirmed by the weak aliphatic C–H symmetric and asymmetric stretching vibrations at 2933 cm ‐1 , 2958 cm ‐1 and bending vibrations at 1436 cm ‐1 (curve c to e). In curve c, absorption bonds at 1039 cm ‐1 and 1157 cm ‐1 correspond to stretching vibration of Ti‐O‐Si and Si‐O, respectively ,. Thus the above results indicate that the functional groups were successfully grafted into the surface of the magnetic NiFe 2 O 4 @TiO 2 nanoparticles.…”