Study On The Synthesis And Properties Of Innovative Metal Oxides Based Visible-light-driven Photocatalysts

Water pollution is a serious environmental problem in our country.The discharge of printing and dyeing wastewater is more than 10% of the total discharge of wastewater in China.Moreover,the printing and dyeing wastewater is characterized as large emission and complex composition.Meanwhile,the dyeing wastewater not only possesses large fluctuation of COD and BOD,but also containing a large amount of heavy metals.Therefore,it is necessary to carry out advanced treatment of printing and dyeing wastewater.At present,there are some shortcomings in the existing treatment technology.Therefore,photocatalytic oxidation technology,as an effective treatment technology,has been widely studied.However,the single photocatalyst is seriously limited to apply in water purification,due to the low light harvesting and the sluggish seperation of photoinduced charges carriers.Therefore,how to construct a new type of high efficiency photocatalyst is an urgent issue neede to be solved.In this paper,different metal oxides catalysts were selected for design and synthesis,and the photocatalysts with high photodegradation and nitrogen fixation properties were studied by morphology regulation and modification.Meanwhile,the possible photocatalytic mechanism is illustated in this paper to provide theoretical support for the application of photocatalytic technology.1.The Ce⁴⁺ and Ag were successfully introduced in TiO₂(Ag/Ce/Ti) nanomaterials via hydrolysis method.And the as-obtained photocatalysts were characterized by a variety of characteristic techniques to investigate their phases,morphologies,structures,optical and electronic properties and photocatalytic performance.Ag/Ce/Ti photocatalyst exhibits an enhanced light absorption and an effective charge separation due to the introduction of Ce⁴⁺ and Ag.As a result,the photocatalytic degradation of reactive blue K-NR over Ag/Ce/Ti is effectively enhance.The Ag/Ce/Ti photocatalyst with high photocatalytic performance and good stability can be applied in organic pollutants treatment in water and environmental purification2.We present a facile approach to preparing a BiOCl_1-xBr_x@AgBr heterostructure using a two-step solvothermal method.The constructed BiOCl_1-xBr_x@AgBr heterostructure can not only effectively utilize the visible light,but also promote the electron migration,resulting in an effective separation of photogenerated electrons and holes.Therefore,the as-prepared Bi OCl_1-xBr_x@Ag Br exhibited efficient photocatalytic activity.The excellent photocatalytic performance and stability provide potential opportunities to utilize BiOCl_1-xBr_x@AgBr for organic pollution treatment of water.3.Flower-like Bi that deposited BiOBr with oxygen vacancies(OVs) has been successfully fabricated via a simple solvothermal method followed by an easy hydrogenated treatment.Bi deposited and oxygen vacancies endowed the H-1.0Bi@BiOBr samples with a dramatically enhanced photocatalytic performance for the degradation of organic pollutants(Rhodamine B and Ofloxacin)and the solar-energy nitrogen fixation.Particularly,the enhanced photocatalytic activity was ascribed to higher BET specific area,enhanced visible-light absorption,effective photoinduced charge separation and suitable amounts of oxygen vacancies.Addionally,the H-1.0Bi@BiOBr samples also showed good photochemical stability under repeated visible-light irradiation.4.BiOBr_xI_1-x composite photocatalysts have been successfully deposited on carbon nanofibers(CNFs) substrate via two steps.The first step involves an electrospinning technique and the second step includes a one-pot solvothermal method.Due to the large surface area and high electrical conductivity,the CNF could easily capture and transfer the electron from the conductor band(CB) of the BiOBr_xI_1-x,thus the photogenerated electrons and holes are effectively separated.As a result,BiOBr_xI_1-x/CNF photocatalysts show a dramatically enhanced photocatalytic organic pollutant degradation and photocatalytic nitrogen fixation.In addition,the immobilized catalyst has good repeatability.5.Plasmonic Bi metal and I^-dopant co-modified Bi₂WO₆ photocatalysts were successfully synthetized through a one-pot solvothermal method.Impurity levels are generated between the conduction band and valence band of Bi₂WO₆ photocatalysts via the I^-dopant,thus enhanced the visible light harvesting and effective separation and migration of photoinduced charge carriers.Moreover,the SPR effect of metallic Bi is also a key factor for the enhancement of light absorption.Meanwhile,metallic Bi can capture electrons and improve the photogenerated charge separation efficiencies.Consequently,I-Bi/Bi₂WO₆ possessed the best photocatalytic performance for degrading BPA,RhB,CoR,SX and AZ.Additionally,the I-Bi/Bi₂WO₆ sample also showed excellent photochemical stability.To sum up,photocatalyst is the key factor for the application of photocatalytic oxidation technology.The photocatalyst exhibits enhanced light harvesting and effiecient separation of photogenerated charges carriers through differernt modifying approaches,such as ion doping,metal deposition,construction of heterostructure and oxygen vacancy modification,etc.Thus,the photocatalytic degradation of organic wastewater and energy conversion performance of the photocatalysts are singnigicatly improved.