| Among the methods of environmental pollution control,photocatalysis has a good prospect and has received great attention in recent years.Therefore,it is important to prepare photocatalyst with excellent performance,which is efficient for pollutant degradation.With the continuous use of semiconductor photocatalyst,people have a systematic understanding of the principle of photocatalysis.When semiconductors are used as photocatalysts,the photoelectronic properties and photocatalytic activity are low because of the rapid recombination of electrons-hole pairs,which were generated under illumination.The semiconductor photocatalytic efficiency can be effectively improved by enhancing the transfer efficiency of photogenerated carriers and prolonging the range of optical response,in which semiconductor materials combine to form heterojunction is an important research topic.As a good electron acceptor with similar properties to n-type semiconductor,POMs can effectively trap the electrons generated under illumination of semiconductor,when POMs and semiconductor recombination.In other words,POMs make the photoelectric performance and photocatalytic efficiency higher.We discussed the synthesis methods of recombination between different semiconductors and POMs to form n-n type or p-n type heterojunction.We have prepared and explored the photoelectric properties and photocatalytic efficiency of Cd S/POMs n-n type heterojunction compounds and NiO/POMs p-n type heterojunction compounds.1.A serial of Cd S/POM(POM denotes polyoxometalate:P2MoxW18-x,x=3,9,15)nanospheres were fabricated through electrostatic self-assembly method.For the first time,the semiconductor properties of the three polyoxometalates were investigated to direct the rational design of the type-II heterojunction photocatalysts.The morphology and semiconducting properties of Cd S/P2MoxW18-xwere characterized by X-ray powder diffraction,scanning electron microscopy,UV–vis diffuse reflectance spectra,Mott-Schottky plots,surface photovoltage spectroscopy and time-resolved photocurrent curves.The formation of type II heterostructure between Cd S and P2MoxW18-xcould efficiently realize the transfer of photogenerated electron,so the photocatalytic activities of Cd S/POMs nanospheres for Cr???reduction were improved significantly.2.In this work,pure Cu In S2?Cu In S2/Ag3PW12O40heterojunction and Cu In S2/Ag3PMo6W6O40heterojunction materials were prepared by solvothermal method,which were fabricated in ethylenediamine.Compared to pristine Cu In S2,the Cu In S2/Ag3PW12O40junction and Cu In S2/Ag3PMo6W6O40junction displayed a remarkable enhancement in their photoelectric properties.Moreover,consistent with the results of photoelectric properties characterization,the photocatalytic performance of heterojunction materials for tetracycline hydrochloride?TC?is better than that of pure Cu In S2materials,and the photocatalytic effect of Cu In S2/Ag3PW12O40p-n junction materials on TC is the best.3.Synthesis of pure NiO materials is by sol-gel method,and the equal amount of NiO?Ag3PW12O40or Ag3PMo6W6O40is compounded into NiO/Ag3PW12O40or NiO/Ag3PMo6W6O40p-n heterojunctions by ball milling.The prepared materials were characterized by IR,Mott-Schottky plots analysis,transient photocurrent measurements,current-voltage curves test,electrochemical impedance spectroscopy and photoluminescence test characterization.The photocatalytic performance of photocatalyst NiO/Ag3PW12O40and NiO/Ag3PMo6W6O40was investigated by photocatalytic degradation of levofloxacin?Levo?.The results of photoelectric characterization and photocatalytic characterization are consistent,both of which prove that the p-n junction material formed by NiO and POMs has better photoelectric properties than that of pure NiO.Ag3PW12O40has better performance of accelerating the transfer of electrons from NiO compared with Ag3PMo6W6O40. |
PDF Full Text Request