Study On The Dye Decomposition By Piezoelectric Catalysis And Pyroelectric Catalysis Of Bismuth Ferrite Nanomaterials And Heterostructure

Environmental pollution has been become a serious problem faced by human society,especially in the textile industry.Because the textile industry needs to meet people’s pursuit of color,resulting in large-scale discharge of organic wastewater.If it is discharged into the environment without treatment,it will lead to environmental pollution.High organic concentration and complex components of dye wastewater make it difficult to decompose.At present,the widely reported photocatalytic technology is a green and promising treatment method,which can generate electron hole pairs by irradiating light to the surface of materials and absorbing light energy,then decompose dye by redox reaction.However,there are some drawbacks that hinder the practical application of photocatalytic dye decomposition,including the low efficiency of solar energy utilization and the lack of response in dark.Therefore,it is necessary to develop new and efficient catalytic technology.In this work,bismuth ferrite（BiFeO₃）was synthesized via a hydrothermal method.The decomposition of Rh B dye using the pure BiFeO₃ catalyst through piezoelectric catalysis and pyroelectric catalysis was investigated.The dye decomposition ratios of piezoelectric catalysis and pyroelectric catalysis are further improved through constructing BiFeO₃/g-C₃N₄ and BiFeO₃/ZnO heterostructure.The main research contents are as follows:1、Piezoelectric catalysis and pyroelectric catalysis of BiFeO₃BiFeO₃ nanosheets were synthesized by hydrothermal method,piezoelectric andpyroelectric properties of BiFeO₃ nanosheets were studied.After 160 min vibration,the decomposition ratio of Rh B dye is about 58.5%.The physical mechanism is that when the catalyst is subjected to external mechanical vibration,due to the piezoelectric effect,a large number of positive and negative charges will be generated on the surface,and the positive and negative charges will react with ions in the dye solution to produce redox reaction.Finally,the purpose of dye decomposition is achieved.The decomposition ratio of BiFeO₃ for Rh B dye solution is～58.1%when the temperature was 25℃～65℃.The physical mechanism is due to the pyroelectric effect,a large number of positive and negative charges generated in the reaction have redox reaction with the dye solution to achieve the purpose of dye decomposition.2、Piezoelectric catalysis and pyroelectric catalysis of BiFeO₃/g-C₃N₄heterostructureBiFeO₃/g-C₃N₄ heterostructure was prepared by chemical water bath deposition method.With the change of g-C₃N₄content,the performance of piezoelectric catalysis and pyroelectric catalysis for dye decomposition was studied.After 160 min of vibration and 120 cycles of temperature fluctuation from 25℃to 65℃,it was found that the dye decomposition ratio was the best when the mass fraction of g-C₃N₄ and BiFeO₃ was 10%,which reached to 95.3%and 94.2%,respectively.The results show that the formation of BiFeO₃/g-C₃N₄heterostructure has significantly improved the piezoelectric and pyroelectric catalytic.The possible physical mechanism is that the formation of heterostructure contributes to the carrier migration and accelerates the process of redox reaction.3、Pyroelectric catalysis of BiFeO₃/ZnO heterostructure at room temperatureBiFeO₃/ZnO heterostructure was prepared by chemical water bath deposition method.The pyroelectric catalytic decomposition of Rh B dye solution at room temperature was studied.After 120 cold-hot cycles at 25℃～65℃,the decomposition ratio of pure BiFeO₃ is～58.1%.Through calculation and comparison,it is found that the best decomposition ratio is～97.0%through used BiFeO₃/3%ZnO.The physical mechanism is that the formation of heterostructure contributes to the migration of carriers and accelerates the process of redox reaction.The active substances produced in the chemical reaction are the main factors for the decomposition of dyes.In addition,the catalyst showed good stability and recycling performance in pyroelectric catalysis experiment.