Preparation And Photocatalytic Properties Of Bismuth Based Semiconductor Ternary Heterojunction Photocatalyst

Bismuth-based semiconductor photocatalysts have many characteristics,such as controllable structure,visible light response,environmental friendliness and abundant raw materials,which have grown an exceedingly vital new-model photocatalytic material.Based on the principle of colloid and interfacial chemical reaction and advantages of bismuth-based materials,the purpose of this paper is to design new ternary bismuth heterojunctions,so as to obtain solar-driven photocatalysts with high adsorption and high photocatalytic activity.The composition,structure,and optical properties of the as-prepared bismuth-based materials in this paper were characterized by XRD,XPS,SEM,TEM,and Uv-Vis DRS,respectively.Eventually,the photocatalysis mechanisms of the obtained materials were thoroughly explored.The main contents of this thesis are as follows:1.Utilizing formamide to undertake the function of carbon source,alkali source and reluctant,Bi/Bi2O2CO3 were synthesized in situ through generating Bi nanoparticles in Bi2O2CO3 utilizing hydrothermal means.Therewith,the in situ formation of BiOI on the surface of Bi/Bi2O2CO3 was realized by employing ion exchange process for founding the Bi/Bi2O2CO3/BiOI ternary heterostructure materials.Under simulated sunlight irradiation,the photocatalytic performance of ternary Bi0I/Bi/Bi2O2CO3 composites for degrading Rhodamine B(RhB)were markedly intensified,thereinto,the sample possessing 20 mol%BiOI manifested the optimal photocatalytic capacity.Uv-Vis DRS and photocurrent experiments showed that the loading BiOI significantly enhanced the visible light response,and the SPR effect of metal bi nanoparticles and construction of p-n type heterojunctions can effectively furtherance separation of photogenerated carrier.Meanwhile,the high surface area can absorb more organic pollutant molecules to participate in the photocatalytic process,which led to the improvement of photocatalytic performance.Based on the results of free radical capture experiments and band potentials,a p-n type heterojunction charge carrier transfer mechanism was proposed to elucidate the possible photocatalytic degradation mechanism.2.The g-C3N4/BiOI/Bi2O2CO3 heterojunction material was rationally designed and successfully prepared via two step in situ transforming process.BiOI nanosheets were firstly deposited on g-C3N4 through atmospheric pressure reflux method and then Bi2O2CO3 was generated on the surface of BiOI nanosheets by an ion exchange process.The photocatalytic properties of ternary composites were investigated via using RhB as the degradation model under simulated sunlight irradiation.g-C3N4/BiOI/Bi2O2CO3 catalysts showed much higher photocatalytic activities than single g-C3N4,or BiOI and dual g-C3N4/BiOI.The enhanced photocatalytic activity of g-C3N4/BiOI/BiO2CO3 should stem from the Z-scheme system,in which BiOI acted as a charge transmission-bridge that greatly shortened the distance for the transfer of charge carriers and thereby resulted in the highly effective separation of charge carriers.Moreover,the larger surface areas and abundant mesoporous structures can make the adsorption capacity of ternary photocatalyst stronger and then supply more activated spots for its photocatalytic reaction.Based on the results of free radical capture experiments and band potentials,a Z-scheme heterojunction charge carrier transfer mechanism was proposed to elucidate the possible photocatalytic degradation mechanism.3.The tubular In(OH)3 precursor was obtained via a composite soft template,in which oxalic acid and CTAB constructed the molecular ordered combination and urea acted as the base source.Then the In(OH)3/InOOH heterojunction was constructed by controlling the heat treatment temperature to lose water and in situ generate InOOH using the In(OH)3 precursor as the hard template.Bi2O2CO3 was introduced into the surface of In(OH)3/InOOH to prepare In(OH)3/InOOH/Bi2O2CO3 ternary heterojunction photocatalyst.Besides,the photocatalytic properties of ternary composites were investigated via using RhB as the degradation model.The study found that In(OH)3/InOOH/Bi2O2CO3 ternary heterojunction material containing 5 mol%BiO2CO3 hold the supreme photocatalytic activity,reaching 99.5%.The enhanced photocatalytic activity stem from ternary heterostructures,which can efficaciously divide the photogenerated carriers.Furthermore,the recyclable utilization capacity of the material was probed,and on account of the results of free radical capture experiments and band potentials,a Z-scheme heterojunction charge carrier transfer mode was proposed to elucidate the possible photocatalytic degradation mechanism.