Morphology Controllable Preparation And Photocatalytic Propertise Study Of Several Nano-Semiconductor Photocatalysts

Using the solar energy to solve the growing global environmental problem and energy crisis is a major global task in the future. The development and utilization of nano-semiconductor photocatalytic materials with novel morphology and structure is a new research hot spot in recent years. In this thesis, with several kinds of semiconductor materials as the research subjects, a series of semiconductors and metal-semiconductors with special morphologies and structures have been prepared controllably by designing preparation methods. The effect of preparation condition on morphology and structure has been studied, and the controllably growth mechanism of materials has been revealed. The catalytic performances of the prepared materials with different morphologies have been tested, and the photocatalytic mechanism has been discussed. The main contents and conclusions of this thesis are as follows.(1) CuO nanospheres(CuO NSs) with porous structure were synthesized by using a simple liquid-phase growth method. Subsequently, Cu2 O microspheres(Cu2O MSs) with hollow porous structure were obtainedby adding glucose solution and adjusting reaction temperature. The controllable growth mechanism, adsorption properties and photocatalytic performances of materials were disccussed. The results showed that the as-prepared CuONSs and Cu2 O MSs samples with porous structure and large surface areas have high adsorptioncapacities for AO7 dye, which are almost 20 times and 5 timesthose of commercial CuO and Cu2 O, respectively. In addition, the as-prepared materials could selectively adsorb anionic dyes due tohighly positive surface charge. Under visible-light irradiation for 3 hours, due to the combined action of photocatalysis and adsorption on Cu2 O MSssample, the decolorization ratios for AO7 and MO solutions with high concentration(50 mg/L) reached to 93.5% and 32.0%, respectively. Deducting the adsorption effect, the decolorization ratios for AO7 and MO solutions by photocatalysis reached to 29% and 21%, respectively.This study provides an experimental method for the controllable synthesis of Cu based oxide semiconductor materials.(2) Novel corncob-like nanocomposites of Ag nanowires(Ag NWs) partly coated with Cu2 O nanoparticles(denoted as Ag-Cu2O) were designed and fabricated by ethylene glycol reduction method for the first time. The preparation conditions and growth mechanism have been studied and discussed. Compared with traditional Ag@Cu2O with fully coated structure, the AgCu2 O nanocorncobs with Ag NWs exposed suitably exhibited much higher photocatalytic activity for photocatalytic degradation of organic pollution. Under the same experiment conditions, the photocatalytic degradation rate of MO onAg-Cu2 O enhanced to 86% from 67% onAg@Cu2O.The novel corncob-like Ag-Cu2 O composites with suitably exposed of Ag NWs surface not only accelerate the phot-oxidation of organic molecules but also suppress the photocorrosion of Cu2 O by a fast electron transfer, resulting in the good stability of Cu2 O. This study presents a well reference value for designing and preparing stable Cu2O-based composite photocatalyst.(3) The hierarchical Ag NPs with a bimodal size distribution were auto-decorated on the surface of rice-like N-TiO2(named h-Ag/N-TiO2) by semiconductor-metal double excitation process under solar light irradiation. The synthesized h-Ag/N-TiO2 was used as plasmonic photocatalyst for ethanol-splitting and exhibited a higher photocatalytic hydrogen production rate(4.7 mmol?h-1?g-1,) than that of Ag NPs universally loaded N-TiO2(2.2 times higher) and pure N-TiO2(1.4 times higher) under UV-visible light. The study has a great significance for the design and preparation of Ag-based plasmon resonance catalyst with high activity and stability.(4) Using copper foil as support and reactant, novel self-assemble peony-like threedimensional(3D) copper hydroxyl phosphate(Cu2(OH)PO4) as a monolithic photocatalyst was synthesized controllably on the copper foil by a solution-growth method.The possiblegrowth process of Cu2(OH)PO4 flowers was revealed by analyzing the correlation of preparation condition and morphology. The photoelectrical property and photocatalytic performance for degradation of organic pollution were evaluated, the relationship between the content of Cu2(OH)PO4 on Cu foil and photocatalytic performances was also investigated. The results indicatedthat this designed 3D monolithic photocatalyst has a good photocatalytic activity and stability for convenient reusing.This study provides a new method for the preparation of monolithic thin film photocatalyst.