| The bismuth-based compounds have attracted great interests,due to their special electronic structure(the hybridization of the Bi6s and 02p levels makes the VB largely dispersed).In addition,Bi2O3 is one of semiconductors with multiple crystal structures(including ?-,?-,?-,?-),possessing either n-type or p-type properties and allowing it to be easily used in sensor,catalysis,and photovoltaic field.Among them,?-Bi2O3 is deeply concerned about owing to the strongest absorption in the visible light region with the smaller band gap(Eg = 2.0-2.4 eV).In this paper,pure ?-Bi2O3 powder was prepared by a Solvothermal-decomposition method,calcined pure spherical Bi2O2CO3 powder at 380? for 2h.And the pure spherical Bi2O2CO3 was prepared by using Bi(NO3)3·5H2O and C6H8O7·H2O as raw materials.Using BPA solution and NOx as target pollutants,the effects of noble metal particles modification and heterojunction formation on the photocatalytic properties of ?-Bi2O3 were studied.The main tasks are as follows:(1)MnOX/?-Bi2O3 photocatalysts composed of MnOx and ?-Bi2O3 were successfully synthesized by a ion-impregnation thermal decomposition method.The grain size of the MnOx/?-Bi2O3 powders were 5-6?m,and the original morphology of pure phase ?-Bi2O3 was basically maintained.The photocatalytic properties of the catalyst were characterized by photocatalytic degradation of organic pollutant BPA and removal of NO..It can been seen that,when the loading amount of MnOx was 2mol%,the degradation rate of S2-MnOx/?-Bi2O3 for BPA solution was 93.1%after irradiated for 40 min under LED light white light(400-800nm);and the NOx removal rate was 38.5%under xenon lamp irradiated with 30 min.And it still has relatively high photocatalytic performance after four cycles.So the sample had high stability.When MnOx loaded on ?-Bi2O3,the hole on the valence band of ?-Bi2O3 was transferred to MnOx,and inhibited the recombination of the photogenerated electron and hole,so that the photocatalytic activity of the ?-Bi2O3 was effectively improved.(2)MoS2/?-Bi2O3 semiconductor photocatalyst was successfully prepared by a ion-impregnation method.The loading amounts of MoS2 nanoparticles were 0.5wt%,lwt%,1.5wt%and 2wt%,respectively,which were recorded as S1-MoS2/?-Bi2O3,S2-MoS2/?-Bi2O3,S3-MoS2/?-Bi2O3 and S4-MoS2/?-Bi2O3 respectively.The microstructure,crystal structure,lattice spacing and optical properties of the target catalyst were analyzed by a series of measurement methods.It was found that the introduction of MoS2 does not change the original morphology of p-Bi2O3 powders.The photocatalytic performance test showed that S2-MoS2/?-Bi2O3 powders exhibited the best photocatalytic activity when the amount of MoS2 was 1 wt%.The degradation rate of S2-MoS2/?-Bi2O3 sample for BPA solution with 20mg/L initial concentration was up to 94.0%after 30 minutes under LED white light(400-800nm)irradiation.In addition,the NOx removal rate was 41.4%after 30 minutes of exposure to the xenon lamp.And the sample of S2-MoS2/?-Bi2O3 has slight inactivation after four cycles.(3)Pd and PdO particles were deposited on ?-Bi2O3 microspheres by a noble metal reduction method,so Pd/PdO/?-Bi2O3 microspheres were prepared.The structure,morphology,and optical property of the samples were analyzed by different measurement methods.The results displayed that the size of the Pd/PdO/?-Bi2O3 powders were 5-6?m,and the original morphology of pure ?-Bi2O3 microsphere was basically maintained.The degradation rate of BPA in S2-Pd/PdO/?-Bi2O3 samples was as high as 96.8%after 30 minutes under white(400-800nm)light of LED lamp irradiation.Its photocatalytic performance has been improved to more than 40%compared with pure phase ?-Bi2O3(53.4%).Also,Under LED monochromatic orange light(595nm),S2-Pd/PdO/?-Bi2O3 samples still exhibited good photocatalytic properties for BPA solution.Therefore the existence of plasma effect of Pd nanoparticles was verified.In addition,the NOx removal rate of S2-Pd/PdO/?-Bi2O3 sample was reached to 47.6%,and it still had relatively high photocatalytic performance after four cycles. |
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