Surface modification of TiO2 nanoparticles with catechol

Surface modification of nanocrystalline TiO2 particles with catechol was found to result in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The undercoordinated defect sites at TiO2 surface are the source of novel enhanced and selective reactivity of the nanoparticle toward bidentate ligand binding. Catechol, an enediol ligand, have the optimal geometry for chelating surface Ti atoms, resulting in a five-membered ring coordination complex and restoration of six-coordinated octahedral geometry of surface Ti atoms.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Thermal properties of nanocomposite film consisting of PVA and shaped Ag nanoparticles

Manipulation of the size and shape of metal nanoparticles has attracted a great deal of attention recently and opened-up possibility for their usage in various fields such as microelectronics and optics. Prismatic and plate-like silver nanoparticles synthesized in water by colloidal chemistry methods, were used as a precursor for preparation of transparent and colored Ag/PVA nanocomposite films. Due to structural anisotropy of prismatic and plate-like silver nanoparticles, confirmed by TEM measurements, in absorption spectrum were observed three surface plasmon resonance bands. In absorption spectrum of Ag/PVA nanocomposite film appears only one absorption band. Interaction between Ag nanoparticles and PVA matrix was followed using FTIR spectroscopy. The thermal properties of Ag/PVA nanocomposite film has been examined using TGA and DSC techniques. The thermal decomposition of the PVA matrix in the presence of shaped Ag nanoparticles is shifted towards higher temperatures for about 14o C in argon atmosphere. Slightly higher thermal stability was obtained during thermo-oxidative degradation process. DSC measurements revealed that shaped Ag nanoparticles incorporated in PVA matrix do not have significant influence on the crystallization temperature changes

Synthesis and characterization of Co2+ doped TiO2 nanoparticles

Scrolled titania nanotubes were synthesized by a hydrothermal method using commercial TiO2 powder in proton-deficient aqueous systems. In presence of CoCl2 extended hydrothermal treatment of TiO2 nanotubes lead to formation Co2+ doped TiO2 nanoparticles. TEM and HRTEM measurement were used for determining the shape, dimension and structure of doped nanoaprticles. XRD confirmed anatase crystalline structure od Co2+ doped TiO2. The presence of Co2+ ions did not induce distortions of the overall anatase crystal structure of TiO2 matrix. The concentration of Co2+ ions was 1.5% compared with the amount of Ti4+ ions.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Bottom-up creation of multifunctional textile nano-entities using TiO2/Ag nanocrystals

The 11th International Conference on Modern Manufacturing Technologies in Industrial Engineering 2023 (ModTech 2023) / hybrid edition, June 14 - 17, Bucharest, Romania, 2023.Invited speaker (Invitation lecture)

Optical properties of Au nanorods/PVA nanocomposite films

Polymer based nanocomposites have emerged as a new class of materials and attracted considerable interest due to their new or much improved optical, electrical and thermal properties. Au nanorods are synthesized in water using seed-mediated growth method in the present of surfactant CTAB and silver ions. The size and shape of Au nanorods (length-width aspect ratio 4) were examined by TEM technique. Colloidal solution of Au nanorods was used as a precursor for synthesis of Au/PVA nanocomposite films. The optical properties of transparent and colored nanocomposite films were evaluated by UV/ViS absorption spectroscopy. The appearance of two surface plasmon resonance bands in absorption spectrum of Au nanorods colloidal solution is consequence of structural anisotropy. Different dielectric properties of PVA polymer compared to water environment induced position changing of the longitudinal and transversal plasmon resonance bands in absorption spectrum of Au nanorods/PVA nanocomposite films

Aerosol-assisted processing of colloidal TiO2nanoparticles

Poster presented at the International Symposium on Advanced Complex Inorganic Nanomaterials (ACIN 2011), September 11-14, 2011 - Namur, Belgiu

Synthesis and characterization of conducting polyaniline nanotubes in the presence of colloidal TiO2 nanoparticles

Conducting polyaniline nanotubes were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, in the presence of colloidal TiO2 nanoparticles of an average diameter ~5 nm. Polyaniline-TiO2 nanocomposite has been characterized by the electrical conductivity measurements, thermogravimetric analysis, FTIR spectroscopy, scanning and transmission electron microscopies. The electrical conductivity of synthesized nanocomposite was 1.1 × 10–3 S cm–1, slightly higher than that of pure polyaniline prepared under the same conditions. Polyaniline nanotubes have an outer diameter of 45–230 nm nm, an inner diameter of 15–130 nm, and a length extending from 0.5 to 2.0 μm.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Novel TiO2/Ag/TiO2 cotton-based nanocomposites for wastewater treatment

The 7th International Conference on the Characterization and Control of Interfaces for High Quality Advanced Materials and the 57th Summer Symposium on Powder Technology 2022 (ICCCI 2022), November 15 - 18, Fujiyoshida, Japan, 2022.Invited speaker (Invitation Lecture)

Theoretical and experimental analysis of droplet-to-particle formation during aerosol processing of colloidal TiO2 nanoparticles

Theoretical and experimental investigation of the particle formation during processing of colloidal nanoparticles in aerosol laminar flow reactor is presented. Simple analytical model taking into consideration all important process parameters, such as physico-chemical properties of the colloidal solution, initial droplet size, residence time and temperature, is developed in order to predict the final particle morphology. The formation of spherical, hierarchically organized, ~450 nm sized TiO2 particles has been followed at 150°C starting from colloidal TiO2 nanoparticle (~4.5 nm) solution as precursor. It has been shown that the final particle morphology is formed in the evaporation/drying stage through the self assembly processes of colloidal nanoparticles collision and aggregation. The dimensionless numbers Re, Nu, Pr and Bi, were used in modeling to briefly describe the transport properties in dispersed system and heat and mass transport phenomena. The predicted particle size and morphology is confirmed by using scanning electron microscopy (SEM/FESEM) and laser diffraction particle size analyzer (LPS). Additionally, closer morphological investigation is performed with transmission electron microscopy (TEM) and nanotomography. Correspondingly, theoretical analysis under this study presents a simple procedure to predict the final morphology and mean particle size during aerosol processing

The interaction between variously shaped TiO2 nanoparticles with UV laser determines the quality of the mass spectra of carbohydrates

The important factor that determines the process of the laser-induced desorption and ionization of molecules for the mass spectrometric analysis is the interaction between the laser light and the substrate. It is of importance that substrate efficiently absorbs laser energy, which will be further rapidly transferred to the analyte. The overall goal in this process is to obtain good quality mass spectrum with low degree of fragmentation. Whereas the application of organic matrices instead of substrates results in the numerous undesired polymerization reactions, which complicate the spectra, and in some cases, even prevent the detection of the ions of interests, nanoparticles as substrates are convenient due to a lower number of background signals and low onset of fragmentation reactions in the gas phase. Titanium dioxide (TiO2) is semiconductor-based and widely used substrate for laser desorption and ionization ((SA)LDI), and when it is in the excited state it transfers an electron or energy into the ground state molecule. This process is called sensitized photoreaction [1]. The desorption/ionization processes on TiO2 nanoparticles are related to the physical properties of the substrate such as ability to absorb and dissipate energy from the irradiating laser light source [2]. TiO2 has a large band gap (bulk anatase: 3.2 eV), and can therefore be used as a SALDI matrix with the N2 laser (337 nm) [3]. The aim of our study is to investigate the influence, which the interaction of the UV laser with TiO2 nanoparticles of various shapes and size has on the quality of the mass spectra of carbohydrates: D-(+)-glucose, D-(+)-maltose, raffinose, arabinose, β-ciclodextrine, substances which are otherwise difficult for mass spectrometric analysis. For this purpose, we used small, nearly spherically shaped colloidal TiO2 nanoparticles (average diameter ~ 5 nm), prolate nanospheroids (length: 40–50 nm, the lateral dimension: 14–16 nm) and nanotubes (length: 100-150 nm, average diameter 11 nm). For comparison, the spectra are acquired also with traditionally used organic matrices. The spectra of carbohydrates with organic matrices are overloaded with matrix signals, in which case the signals arising from the analyte of interest are suppressed, or it is possible to detect only adducts with matrix. Laser-induced ionization on nanostructures offers alternative ionization pathways through the formation of Na+ and K+ adducts with appreciable yield [4]. TiO2 nanotubes showed extraordinary properties for detection of carbohydrates. Arabinose was detectable only with TiO2, and D-(+)-glucose and D-(+)-maltose were detected in negative ion mode, which was not the case with other organic matrices and substrates. Not only the highest intensities of mass peaks but also the smallest coefficient of variation was achieved with TiO2 nanotubes. Taken toghether, TiO2 nanotubes, due to their size and the shape, have the most suitable physical properties for the substrate in the SALDI technique. The laser intensity was kept as low as possible in order to prevent fragmentaion. Higher laser intensity is required for the process of desorption/ionization when TiO2 NPs are used (2400 i.u.), but for TiO2 PNSs and TiO2 nanotubes were lower and nearly the same 1950 and 2000 i.u., respectively. In conclusion, larger, tube-shaped TiO2 substrates more efficiently absorb the laser energy and transfer it to the carbohydrates, enabling their desorption/ionization and preventing their fragmentation.V International School and Conference on Photonics and COST actions: MP1204, BM1205 and MP1205 and the Second international workshop "Control of light and matter waves propagation and localization in photonic lattices" : PHOTONICA2015 : book of abstracts; August 24-28, 2015; Belgrad