| Photocatalytic technology is a promising approach which can solve current environmental and energy challenges by converting renewable solar energy into chemical energy.Degradation of organic dyes and oxygen evolution from water splitting are two important applications of photocatalytic technology,which has great significance to the emission reduction of environmental pollutants and production of H2.Bismuth vanadate has good visible light response,of which the monoclinic scheelite structure has the advantage of non-toxic,low price,narrow band gap and stable chemical properties.Therefore,Bismuth vanadate has been widely applied in the photocatalytic degradation of pollutants,producing oxygen and solar cells.However,the electron hole pair produced by bismuth vanadate after illumination is easy to recombine,which result in low electron transport efficiency and poor carrier mobility of BiVO4.Polyoxometalate?POM?,a kind of good electron acceptor,can suppress the rapid recombination of electron and hole pairs by capturing and transmitting photogenerated electrons produced by semiconductor,thus improve the photoelectric properties of the semiconductor.At the same time,the content of polyoxometalate also has a certain effect on the growth of semiconductor crystals.In this article,we prepared BiVO4 and POMs-BiVO4complexes in several methods and studied photoelectric properties of complexes.The specific work is as follows:1.BiVO4 was synthesized by hydrothermal method using Bi?NO3?3·5H2O and NH4VO3as raw materials.PMo12 was introduced into BiVO4 through self-assembly and PMo12-BiVO4complex was synthesized successfully.The photocatalytic activities of BiVO4 and PMo12-BiVO4 were evaluated by photodegradation of methylene blue and nitrogen dioxide.Basic characterization show that crystalline phase of BiVO4 change in the different introduction of PMo12.Comparing with pure BiVO4,the photocatalytic performance of complex improves about 1.5 times and complex exhibited higher stability than BiVO4.BiVO4and PMo12-BiVO4 composite electrodes were prepared by screen printing and their photochemical properties were studied.The experimental results show that introduction of PMo12 can improve the photoelectric performance of BiVO4 obviously.2.BiVO4,BiVO4-bi-CoPc,PW12-BiVO4 and PW12-BiVO4-bi-CoPc nanofilm electrodes were prepared by organometallic decomposition.Photocatalytic activities of pure BiVO4 and complex were studied by the photodegradation of nitrogen dioxide under visible light irradiation.The result show that introduction of PW12 can obviously improve the photoelectric performance of BiVO4,and the multiplier is 3,and introduction of bi-CoPc can further enhance the photoelectric properties of PW12-BiVO4 composite by an improving ratio of 3.5.The introduction of bi-CoPc alone could also improve the photocatalytic performance of BiVO4 to a certain extent.All conclusions were confirmed by photoelectric chemical test and fluorescence measurements.In composite system,PW12 captures and transmits photogenerated electrons effectively,while bi-CoPc plays a good hole transport role.3.The cadmium sulfide was synthesized by hydrothermal method.Then BiVO4-CdS composites with different content of CdS were synthesized by hydrothermal method,and PW12 was introduced by immersion method to prepare PW12-BVO-CdS composite.The photocatalytic performances of BiVO4,BiVO4-CdS and PW12-BVO-CdS composite were studied by photodegradation of methylene blue under visible light irradiation.The result shows that introduction of CdS obviously enhance the photocatalytic performance of BiVO4,and the introduction of PW12 further enhanced the photoelectric properties of BVO-CdS composite.The electrodes of BiVO4-CdS and PW12-BiVO4-CdS composite were prepared by screen printing and their photochemical properties were studied.Correlation analysis results show that fast recombination of photogenerated electron-hole pair from BiVO4 can be effectively inhibited in composite system. |
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