Study On Microwave Synthesis Of New Photocatalytic Materials And Their Photocatalytic Properties

There is a close relationship between the properties and the grain sizes of the material. Upon decreasing the grain size of the material to nanometer level, great changes will take place to the case of the materials. Inorganic nano-materials, compared to the bulk materials, have unique physicochemical properties, such as small size effect, surface effect, quantum size effect and dielectric confinement effect. Due to these advanced properties, the inorganic nano-materials exhibit potential applications in the field of catalysis, photo-electrocity, biology etc.Microwave synthesis route has become one of the potential technologies for the chemical synthesis of functional materials. As a green method, it has been widely used in the field of tailoring and fabricating nano-materials. As known, the traditional hydrothermal method can only allow heating the materials from outside to inside. Compared to the heating mode of hydrothermal method, microwave irradiation could trigger heating by two main mechanisms, namely dipolar polarization and ionic conduction. The microwave heating was based on the electromagnetic field of microwave dielectric loss. Such route could be favorable for achieving uniform heating system, improving the efficiency of the reaction, and prohibiting the side effects, improving the yield, increasing the reproducibility, and so on. Advanced microwave reactor equipped with online controlling program could allow flexible reactions. Via choosing various heating media, inorganic nano-materials with different morphologies could be obtained. Thus, it is very important to combining the microwave synthesis technology with various heating media for exploring nanomaterials with different morphologies, structures, and properties. Based on the above advantages, this paper will focus on the following parts:1. Microwave ionothermal synthesis of high energy facets exposed mesoporous single-crystal titanium dioxide cubics for photocatalytic oxidation of NOxThe traditional approach to the synthesis of mesoporous materials aimed at crystallizing the target materials from thermal decomposition of the precursor species infiltrated into the pores of a sacrificial template. However, the morphology and the facets exposed rates are hard to be controlled by using traditional method. Herein, we adopted a “seeding” method to growing nano-crystals under the microwave irradiation by choosing ionic liquids as green solvents for controlling the crystal facets. During the synthesis process, MCM-41 nanospheres were utilized as a template for trapping Ti O2 crystals in its cavities. MCM-41 nanospheres possessed short pore channels, allowing the growth of titanium dioxide seeds in the pores. In addition, ionic liquids(1-methyl imidazole tetrafluoroborate) could be used to increase the exposed percentages of high energy facets. The as-formed mesoporous single-crystallized anatase titanium dioxide cubic exhibited good activity for photocatalytic oxidation of NOx.2 Microwave assisted synthesis of copper nanowires enhanced ZIF-8 for hydrogen evolution based on ammonia boraneOne-dimensional copper nanowires were rarely used in the hydrogen evolution based on ammonia borane due to the low specific surface area, poor catalytic activity, and few recyclabilities. ZIF-8 owned large specific surface area, high porosity, and the ability to improve the both catalytic efficiency and stability of copper nanowires in ammonia borane hydrogen evolution. Herein, the copper nanowires/ZIF-8 composites were synthesized by a microwave assisted heating method. The size of ZIF-8 coated on the cooper nanowires could be tunned by increasing the amount of copper. High hydrogen evolution rates were achieved upon using such composites as catalysts.3 Microwave assisted synthesis of carbon nanotubes composites enhanced ZIF-8 for the photo-reduction of CO2Carbon nanotubes own good electron transfer ability, but its low surface area limited its application. On contrary, ZIF-8 has a large specific surface area, good activity in adsorption CO2. Unfortunately, the photo generated electron-hole pairs produced from ZIF-8 was easy to be recombined, limiting the application of ZIF-8. Carbon nanotube/ZIF-8 composites were synthesized by a microwave assisted heating route. The catalytic activity of the composites was much higher than that of both ZIF-8 nanoparticles and carbon nanotubes in the photo-reduction of CO2.