The Preparation And Optical Performance Of Bismuth-based Semiconductor Photocatalytic Materials

There are two major problems facing humanity which are environmental pollution and energy shortages.To solve the aforementioned problems,Photocatalytic oxidation technology has been proposed by researchers and has attracted great attention.Semiconductor nano-catalyst is one of the most effective materials dealing with environmental pollution.To dates,titanium dioxide photocatalyst has been highly used in the purification of toxic and harmful gases and waste water due to its characteristics of biological and chemical inertness,strong oxidation,low toxicity and cheap availability.However,due to its wide band width?3.2 eV?,it can only absorb ultraviolet light and has no response to visible light,thus greatly restricting its efficient use of solar energy.In order to avoid the above problems,bismuth semiconductor materials have become the preferred one of photocatalytic materials,because of its high efficiency,stable,low toxicity and can realize high efficient degradation of organic pollutants in visible light etc.However,ultraviolet-visible light accounts for 45%percent of the solar spectrum,and more than 55%percent of the solar spectrum is not used.In addition,the normal bismuth-basedsemiconductors photocatalysts have the lower separation efficiency of photogenerated electrons and holes,and the slower migration rate of carrier,which seriously affects its photocatalytic efficiency.In order to improve the photocatalytic activity of semiconductor materials,the researchers have done a lot of work,such as morphology control of required samples,introduction of defects,cocatalyst loaded and quantum dots doped catalysts,thus,the photocatalysts are made corresponding modification.In this word,it mainly studies the bismuth molybdate and tungstate and bismuth vanadate bismuth controllable synthesis,and on this basis,detailed introduce the synthetic mechanism of bismuth molybdate new morphology and efficient degradation and nitrogen fixation ability.Besides,the introduction of oxygen defects over bismuth vanadate and the cocatalysts load to the photocatalytic effect promotion mechanism of bismuth vanadate are two mainly research contents for the chemical energy efficient conversion.This paper is divided into four parts:First of all,the different morphology bismuth tungstenate,bismuth vanadate and bismuth molybdate were prepared via the traditional simple solvothermal method through regulating different solvents,an amount of raw materials,reaction temperature,reaction time and other variables in reaction system.Furthermore,the photocatalytic activity effects of catalyst with different morphology structures were discussed in detail through a series of characterization methods.Under the same conditions of photocatalysis test,Bi₂WO₆ with the most suitable shape reached about 99%within 80 minutes,BiVO₄ reached more than 80%,and Bi₂MoO₆reached about 99.9%for the degradation of RhB dye.Secondly,according to the preliminary morphological control experiment,bismuth molybdate with multilayer porous micron box structurewas successfully synthesized.Due to its large specific surface area and more than the active site,micronbox bismuth molybdate show excellent photocatalytic activity for organic pollutants degradation and nitrogen fixation compared to other morphology of bismuth molybdate.Thirdly,we further study olive-shape bismuth vanadateto further understand the influence factors of photocatalytic activity.The existence of oxygen vacancy defects on bismuth vanadate surface not only broaden its light response range from the visible to near-infrared light,but also can effectively restrain photogenerated electron-holes recombination.Thus,its photocatalytic activity was improved.In addition,a small size Ag nanoparticle was successfully loaded on bismuth vanadate with oxygen vacancy defects through photoreduction.The synergistic action of the surface plasma resonance effect of silver nanoparticles and defect engineering has played a key role in the efficient degradation of organic pollutant rhodamine B over bismuth vanadate.In a word,bismuth-based oxide was synthesized through solvothermal method,light reduction method and calcined.Simultaneously,we had done the corresponding modification for obtained samples.And characterization and photocatalytic performance of the samples were researched.