Study On Synthesis And Photoelectricity Properties Of Layered Compound-molybdenum Trioxide

In this thesis, the synthesis and application of different phases MoO₃ layered compounds were probed. Through the liquid synthesis routes such as hydrothermal method, chemical deposition, ion exchange etc, the thermodynamically stable a-MoO₃ and metastable h-MoO₃ were synthesized. The various morphologies of the products include nanorod, nanoparticle and so on. On this basis, the assembly of microrods from nanoparticles and the nanoparticle films were obtained. The electrochemical properties of lithium intercalation into the MoO₃, the photochromism performance of the MoO₃ films and the behavior of MoO₃ in photocatalytic decoloration of dyes were discussed separately. The contexts of this thesis are brief concluded as:1. Orthorhombic is thermodynamically stable structure of MoO₃, and hexagonal is metastable structure of MoO₃ Compared with stable a-MoO₃, the preparation of metastable h-MoO₃ is more difficult. The h-MoO₃ microrods were obtained by aqueous recrystallization of commercialα-MoO₃. Further more, metastable h-MoO₃ nanorods were hydrothermal synthesized by the use of inorganic K⁺ as the template. Theα-MoO₃ nanothreads were also produced by the combination of chemical deposition and hydrothermal synthesis. Electrochemical performance of the products was studied vs. Li metal at 0.1 mA.cm^-2 (voltage range 1.2～3.5V). The results indicate that h-MoO₃ microrods, h-MoO₃ nanorods,α-MoO₃ nanothreads delivered the first discharge specific capacity of 375,440,428mAh/g, respectively. Hence, synthesized h-MoO₃ nanorods show potential to be the idea candidate material of lithium ion battery.2. Using Cetyltrimethyl Ammonium Bromide (CTAB) as the template, the a-MoO₃ and h-MoO₃ microrods were obtained through nanoparticles self-assembled in the solution. When no CTAB was added in the reaction,α-MoO₃ nanoparticles were produced. The behaviors of them in photocatalytic decoloration of dyes were observed: assembly and unassembly of MoO₃ materials had the similar decoloration rate (Dï¼…), but assembly of MoO₃ microrods were easier to depart from the solution and had good catalytic recycle. In our research,α-MoO₃ exhibited much higher decoloration rate than that of h-MoO₃ with or without sunlight. Furthermore, we found that both phases of MoO₃ could change color of Congo red dye; sunlight had no effect on this process.3. Amorphous, h-MoO₃ andα-MoO₃ film were prepared on the surface of glass substrate by ion exchange technology. SEM photos show that the film was consisted of nanoparticles which average diameter is about 50nm. The photoluminescence property of the films was studied; three phases of MoO₃ films all have one fluorescence peak at 466nm, h-MoO₃ film has one more fluorescence peak at 636nm, which was cause of absorptable oxygens in its structure. Comparing theâ–³ABS of UV-vis spectra, amorphous MoO₃ film exhibited highest photochromic response, which photochromism mechanism was discussed.