Chemical and electrochemical synthesis of nanosized TiO2 anatase for large area photon conversion

We report on the synthesis of nanocrystalline titanium dioxide thin films and powders by chemical and electrochemical deposition methods. Both methods are simple, inexpensive and suitable for large scale production. Air annealing of the films and powders at T 500 C leads to densely packed nanometer sized anatase TiO2 particles. The obtained layers are characterized by different methods such as X ray diffraction XRD , transmission electron microscopy TEM , scanning electron microscopy SEM , X ray photoelectron spectroscopy XPS and atomic force microscopy AFM . Titanium dioxide TiO2 anatase phase with 101 preferred orientation has been obtained for the films deposited on glass; indium doped tin oxide ITO and quartz substrates. The powder obtained as byproduct consists of TiO2 with anatase phase as well. Key words Chemical synthesis, TiO2 anatase , Thin films, Characterizatio

TiO2 and TiO2 SiO2 thin films and powders by one step soft solution method Synthesis and characterizations

Simple soft solution method has been developed to synthesize films and powders of TiO2 and mixed TiO2 SiO2 at relatively low temperatures. This method is simple and inexpensive. Furthermore reactor can be designed for large scale applications as well as to produce large quantities of composite powders in a single step. For the preparation of TiO2, we used aqueous acidic medium containing TiOSO4 and H2O2, which results in a peroxo titanium precursor while colloidal SiO2 has been added to the precursor for the formation of TiO2 SiO2. Post annealing at 500 C is necessary to have anatase structure. Resulting films and powders were characterized by different techniques. TiO2 anatase phase with 101 preferred orientation have been obtained. Also in TiO2 SiO2 mixed films and powders, TiO2 anatase phase was found. Fourier Transform Infrared spectroscopy FTIR results for TiO2 and mixed TiO2 SiO2 films have been presented and discussed. The method developed in this paper allowed obtaining compact and homogeneous TiO2 films. These compact films are highly photoactive when TiO2 is used as photoanode in an photoelectrochemical cell. Nano porous morphology is obtained when SiO2 colloids are added into the solution. Key words TiO2, TiO2 SiO2, Synthesis, Characterizations, Photoactiv

Controlled synthesis of ZnO nanostructures with assorted morphologies via simple solution chemistry

In the present investigation, we report the reproducible simple solution chemistry towards synthesis of ZnO nanostructure on fluorine doped tin oxide FTO coated glass substrate in aqueous medium at low temperature gt;100 C . The different preparative parameters such as deposition time, bath temperature, concentration of precursor solution, pH of the bath etc. were optimized to get fibrous nanoflakes, nanobeads, nanoparticles, cactus and highly crystalline 1D nanoneedles amp; hexagonal nanorods of ZnO. However, the as deposited film consists of mixture of zinc hydroxide [Zn OH 2] and ZnO. In the present work, to get pure ZnO phase, the as deposited films were air annealed at relatively lower temperature 200 C . The annealed ZnO films deposited by CBD and SILAR were characterized for structural, surface morphological, optical properties and surface wettability studies etc. The simplicity of the synthesis route coupled with the variety of ZnO nanostructures is manifest to be an important candidate for nanoscale devices. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . ..................................234 2. Experimental section . . . . . . . . . . . . . . . . . . ................................234 2.1. Synthesis of ZnO film by soft chemical route . . . . . . . . . . . . . .234 2.1.1. Synthesis and reaction mechanism of chemical bath deposited ZnO on FTO coated glass substrate . . . . . . . . . . . . . . . . . . . . . . 234 2.1.2. Synthesis of ZnO film by CBD on FTO coated glass substrate . . . . 236 2.1.3. Deposition and reaction mechanism of ZnO film by SILAR on FTO coated glass substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 2.1.4. Synthesis of nanostructured ZnO film by CBD over seed ZnO layer . . . . . . 237 2.1.5. Synthesis of ZnO by CBD over seed ZnO layer using acetate bath . . 237 2.1.6. Synthesis of ZnO by CBD over seed ZnO layer using nitrate bath . . . . . . . .237 3. Instrumentation . . . . . . . . . . . . 237 4. Characterizations . . . . . . . . . . . . . . . . . . . . . . . . .237 4.1. Structural characterization . . . . . . . . . . . . 237 4.2. Optical absorption and band gap measurement . . . . . . . .238 4.3. Wettability test . . . . . . . . . . . . . . . . . . . . . . . 239 4.4. Morphological studies . . . . . . . . . . . . . . . . . 239 5. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 241 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24