Ting Zhao,Ruifeng Qian,Yang Tang,Jing Yang,Yitao Dai,Wan In Lee,Jia Hong Pan
Although considerable progress has been achieved in the preparation of uniform hydrous TiO2 spheres (HTS) through the sol–gel process, there is plenty of room left in tailoring the size and morphology of HTS on the deep-submicron scale or even nanoscale since the diameters of the so far reported HTS are mostly on the (sub)micron scale (0.3–1.2 μm). Here, we develop a novel titanium tetraisopropoxide (TTIP)–organic acid (OA)–acetonitrile (ACN)–methanol (MeOH)–H2O system, which facilitates the control of nanoporous HTS to the range of 50–300 nm. The synthetic parameters including OA, (co-)solvent, concentration of precursor, and reaction temperature are comprehensively optimized, aiming at reproducible preparation and precise size control. Among the various OAs, n-valeric acid presents the best capability in controlling the spherical morphology and size uniformity. The synthesized amorphous HTS containing numerous micropores and mesopores show excellent hydrothermal stability and offer suitable self-template for the subsequent synthesis of mesoporous anatase TiO2 spheres (MAT) with a large surface area of 99.1 m2/g. The obtained TiO2 deep-submicrospheres and nanospheres with tunable sizes show great potential in various research fields.
Xianfeng Wang,Fuhai Cui,Jinyou Lin,Bin Ding,Jianyong Yu,Salem S. Al-Deyab
This paper describes the detection of formaldehyde through analyses of the resonance frequency signal from quartz crystal microbalance (QCM) sensors coated with a novel organic–inorganic hybrid sensing coating. Nanoporous titanium dioxide (TiO 2 ) fibers with high Brunauer–Emmett–Teller (BET) surface area (68.72 m 2 /g) were fabricated by electrospinning a sol–gel titanium tetraisopropoxide (TIP)/polystyrene (PS) composite solution and following calcination process. Ethylene glycol (EG) dispersed TiO 2 nanofibers were drop casted onto the electrode of QCM, followed by the functionalization of the sensing polyethyleneimine (PEI) on the fibers. The nanoporous TiO 2 fibers covered with PEI layers worked as a highly sensitive sensing interface to provide output signal for weight changes during exposure to formaldehyde vapor. The developed formaldehyde-selective sensors exhibited rapid response and low detection limit (1 ppm) at room temperature . This is because the high specific surface area of the electrospun nanoporous TiO 2 fibers and efficient nucleophilic addition reaction between formaldehyde molecules and primary amine groups of PEI. Our new synthetic methodology promises to be a powerful approach to fabricating hybrid organic–inorganic nanostructures on QCM for gas sensing and chemical analysis.
The purpose of the nano-porous TiO 2 modification on TC26 (Ti-13 Nb-13Zr) alloy is to settle the issue that the surface inertness of titanium alloys restricts bioactivity and osseointegration of artificial implants . Secondary constant current anodization was conducted to realize the efficient fabrication of the TiO 2 composite nano-porous arrays containing the terminal small-diameter nanopores and the upper large-diameter nanotubes . The oxygen bubble mould theory has revealed the anodization mechanism of the TiO 2 nano-porous arrays. The anodization parameters and heat treatment conditions are both able to elicit influence on morphology, chemical composition , surface properties and biocompatibility of the as-fabricated samples. The interaction of MC3TC-E1 mouse pre-osteoblasts with a series of TiO 2 nano-porous arrays fabricated by primary anodization (PA) and secondary anodization (SA) was investigated by the MTT assay and alkaline phosphatase (ALP) activity assay. The response of the seeded MC3TC-E1 pre-osteoblasts to the as-fabricated samples with various nano-scale dimensions has indicated that appropriate nano-porous morphologies and heat treatment conditions have the capacity to augment cell adhesion, growth, differentiation and functionality. Such fabrication route in this research has provided a promising prospect for development of artificial implants.
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