BiOBr基光催化材料的制備與性能研究
發(fā)布時(shí)間：2018-08-24 15:28
【摘要】：BiOBr(溴氧化鉍)是一種新型可見光響應(yīng)的半導(dǎo)體光催化材料,因其適中的禁帶寬度、開放式層狀結(jié)構(gòu)、較高的氧化能力和間接躍遷模式而備受人們關(guān)注。如何提高BiOBr的光催化活性,成為現(xiàn)階段亟需解決的問題。將BiOBr與其他半導(dǎo)體材料復(fù)合形成異質(zhì)結(jié)構(gòu),能夠有效降低BiOBr光生電子-空穴對(duì)的復(fù)合的幾率,從而改善BiOBr的光催化性能。本文選用氯氧化鉍(BiOCl)、氧化鋅(ZnO)、釩酸鉍(BiVO_4)和還原氧化石墨烯(RGO)分別與BiOBr復(fù)合并對(duì)其光催化性能進(jìn)行研究。光催化降解實(shí)驗(yàn)結(jié)果表明:復(fù)合后的BiOBr基光催化劑的光反應(yīng)速率和反應(yīng)程度在一定程度上均高于純相BiOBr。具體內(nèi)容如下:1、BiOCl/BiOBr復(fù)合材料的制備與光催化性能研究:以檸檬酸為絡(luò)合劑,采取水熱法制備了花球狀BiOCl/BiOBr復(fù)合材料。利用X射線衍射(XRD)、掃描電子顯微鏡(SEM)、紫外-可見漫反射光譜(DRS)和光致發(fā)光光譜(PL)等手段對(duì)樣品的組成與形貌及光吸收性能進(jìn)行了表征;并以亞甲基藍(lán)(MB)為目標(biāo)降解物在模擬太陽光下研究了BiOCl/BiOBr的光催化活性�；ㄇ驙頑iOCl/BiOBr復(fù)合材料比純相鹵氧化鉍材料表現(xiàn)出更高的光催化活性,其中BiOCl0.1Br0.9經(jīng)60 min光反應(yīng)后對(duì)MB的降解率達(dá)80%。2、BiOBr/ZnO復(fù)合材料的制備與光催化性能研究:以六水硝酸鋅為鋅源,在堿性條件下制備出ZnO的前驅(qū)物,在無表面活性劑,水熱條件下制備出BiOBr/ZnO復(fù)合物。通過XRD、SEM、TEM、DRS和PL等手段對(duì)產(chǎn)物進(jìn)行了表征。結(jié)果顯示出BiOBr和ZnO制備出的p-n異質(zhì)結(jié)有效地減少了光生電子與空穴的復(fù)合概率。其中BZ-3(Bi原子與Zn原子的摩爾比為3:1)表現(xiàn)出最好的催化性能。自由基捕獲實(shí)驗(yàn)結(jié)果顯示·OH、h+和·O2-等活性粒子參與反應(yīng),促進(jìn)光催化反應(yīng)。3、BiOBr/BiVO_4復(fù)合材料的制備與光催化性能研究:以硝酸鉍、溴化鉀和釩酸銨為原料,利用水熱法制備了BiOBr/BiVO_4催化劑。XRD、SEM和EDS表征表明BiOBr成功與BiVO_4復(fù)合。通過亞甲基藍(lán)(MB)的降解評(píng)估BiOBr/BiVO_4的光催化性能。0.5BiOBr:0.5BiVO_4復(fù)合材料顯示出比純BiVO_4和BiOBr更高的吸附能力,光催化活性最佳�；谶@兩種半導(dǎo)體的相對(duì)帶位置提出了可能的光催化機(jī)理:復(fù)合形成的p-n型異質(zhì)結(jié)促使光生電子與空穴的分離,內(nèi)建電場(chǎng)也會(huì)促進(jìn)光生載流子的轉(zhuǎn)移。4、BiOBr/RGO復(fù)合材料的制備與光催化性能研究:在CTAB輔助水熱條件下,將氧化石墨烯(GO)與BiOBr復(fù)合成功制備出不同比例的BiOBr/RGO。通過XRD、SEM、FT-IR、DRS、PL等手段表征了催化劑的結(jié)構(gòu)、形貌、元素組成和光學(xué)性質(zhì)等。以亞甲基藍(lán)為模型探究了可見光下BiOBr/RGO的光催化劑活性,對(duì)反應(yīng)機(jī)理進(jìn)行了探討:石墨烯的沉積顯著改變材料的吸光能力,且BiOBr的光生電子易被石墨烯捕獲,從而促進(jìn)了光生電子—空穴對(duì)的分離,提高了光催化反應(yīng)效率。
[Abstract]:Bismuth bromide (BiOBr) is a novel visible light-responsive semiconductor photocatalytic material, which has attracted much attention due to its moderate band gap, open lamellar structure, high oxidation ability and indirect transition mode. How to improve the photocatalytic activity of BiOBr has become an urgent problem at present. Combining BiOBr with other semiconductor materials to form heterostructure can effectively reduce the probability of recombination of BiOBr photogenerated electron-hole pairs and thus improve the photocatalytic performance of BiOBr. In this paper, bismuth chloride bismuth oxide (BiOCl),) zinc oxide (ZnO), (BiVO_4) and reduced graphene oxide (RGO) were used to combine with BiOBr and their photocatalytic properties were studied. The results of photocatalytic degradation experiment showed that the photoreaction rate and reaction degree of the composite BiOBr based photocatalyst were higher than those of pure BiOBr. to some extent. The main contents are as follows: (1) the preparation and photocatalytic properties of BiOCl / BiOBr composites were studied. The spherical BiOCl/BiOBr composites were prepared by hydrothermal method with citric acid as the complexing agent. The composition, morphology and optical absorption properties of the samples were characterized by X-ray diffraction (XRD),) scanning electron microscope (XRD), (SEM), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of methylene blue (MB) was studied under simulated sunlight. Compared with pure bismuth halide composite, the flower spherical BiOCl/BiOBr composite showed higher photocatalytic activity. The degradation rate of MB by BiOCl0.1Br0.9 reached 80. 2% after 60 min photoreaction, and the preparation and photocatalytic properties of the composite were studied: zinc nitrate hexahydrate was used as zinc source. The precursor of ZnO was prepared under alkaline condition, and the BiOBr/ZnO complex was prepared under hydrothermal condition without surfactant. The products were characterized by XRD,SEM,TEM,DRS and PL. The results show that p-n heterojunction prepared by BiOBr and ZnO can effectively reduce the recombination probability of photogenerated electrons and holes. BZ-3 (the molar ratio of Bi atom to Zn atom is 3:1) shows the best catalytic performance. The results of free radical capture experiments showed that active particles such as OH,h and O _ 2- participated in the reaction, which promoted the preparation and photocatalytic properties of the photocatalytic reaction .3BiOBr-BiVO4 composite: bismuth nitrate, potassium bromide and ammonium vanadate were used as raw materials. BiOBr/BiVO_4 catalyst was prepared by hydrothermal method. The results of SEM and EDS showed that BiOBr was successfully combined with BiVO_4. The photocatalytic activity of BiOBr/BiVO_4 was evaluated by the degradation of methylene blue (MB). 0.5BiOBr0.5BiVO4 composite showed higher adsorption ability than pure BiVO_4 and BiOBr, and the photocatalytic activity was the best. Based on the relative band position of the two semiconductors, a possible photocatalytic mechanism is proposed: the p-n heterojunction formed by the composite leads to the separation of photogenerated electrons from holes. The built in electric field can also promote the transfer of photogenerated carriers. The preparation and photocatalytic properties of the photogenerated BiOBr-RGO composites: under the CTAB assisted hydrothermal condition, the different ratio of BiOBr/RGO. was successfully prepared by combining graphene oxide (GO) with BiOBr. The structure, morphology, elemental composition and optical properties of the catalyst were characterized by XRD,SEM,FT-IR,DRS,PL. The photocatalytic activity of BiOBr/RGO under visible light was investigated by using methylene blue as a model. The reaction mechanism was discussed: the photoelectron of BiOBr was easily captured by graphene, and the photoabsorption ability of the material was significantly changed by the deposition of graphene. Thus, the separation of photogenerated electron-hole pairs was promoted, and the efficiency of photocatalytic reaction was improved.
【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
本文編號(hào)：2201244
[Abstract]:Bismuth bromide (BiOBr) is a novel visible light-responsive semiconductor photocatalytic material, which has attracted much attention due to its moderate band gap, open lamellar structure, high oxidation ability and indirect transition mode. How to improve the photocatalytic activity of BiOBr has become an urgent problem at present. Combining BiOBr with other semiconductor materials to form heterostructure can effectively reduce the probability of recombination of BiOBr photogenerated electron-hole pairs and thus improve the photocatalytic performance of BiOBr. In this paper, bismuth chloride bismuth oxide (BiOCl),) zinc oxide (ZnO), (BiVO_4) and reduced graphene oxide (RGO) were used to combine with BiOBr and their photocatalytic properties were studied. The results of photocatalytic degradation experiment showed that the photoreaction rate and reaction degree of the composite BiOBr based photocatalyst were higher than those of pure BiOBr. to some extent. The main contents are as follows: (1) the preparation and photocatalytic properties of BiOCl / BiOBr composites were studied. The spherical BiOCl/BiOBr composites were prepared by hydrothermal method with citric acid as the complexing agent. The composition, morphology and optical absorption properties of the samples were characterized by X-ray diffraction (XRD),) scanning electron microscope (XRD), (SEM), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of methylene blue (MB) was studied under simulated sunlight. Compared with pure bismuth halide composite, the flower spherical BiOCl/BiOBr composite showed higher photocatalytic activity. The degradation rate of MB by BiOCl0.1Br0.9 reached 80. 2% after 60 min photoreaction, and the preparation and photocatalytic properties of the composite were studied: zinc nitrate hexahydrate was used as zinc source. The precursor of ZnO was prepared under alkaline condition, and the BiOBr/ZnO complex was prepared under hydrothermal condition without surfactant. The products were characterized by XRD,SEM,TEM,DRS and PL. The results show that p-n heterojunction prepared by BiOBr and ZnO can effectively reduce the recombination probability of photogenerated electrons and holes. BZ-3 (the molar ratio of Bi atom to Zn atom is 3:1) shows the best catalytic performance. The results of free radical capture experiments showed that active particles such as OH,h and O _ 2- participated in the reaction, which promoted the preparation and photocatalytic properties of the photocatalytic reaction .3BiOBr-BiVO4 composite: bismuth nitrate, potassium bromide and ammonium vanadate were used as raw materials. BiOBr/BiVO_4 catalyst was prepared by hydrothermal method. The results of SEM and EDS showed that BiOBr was successfully combined with BiVO_4. The photocatalytic activity of BiOBr/BiVO_4 was evaluated by the degradation of methylene blue (MB). 0.5BiOBr0.5BiVO4 composite showed higher adsorption ability than pure BiVO_4 and BiOBr, and the photocatalytic activity was the best. Based on the relative band position of the two semiconductors, a possible photocatalytic mechanism is proposed: the p-n heterojunction formed by the composite leads to the separation of photogenerated electrons from holes. The built in electric field can also promote the transfer of photogenerated carriers. The preparation and photocatalytic properties of the photogenerated BiOBr-RGO composites: under the CTAB assisted hydrothermal condition, the different ratio of BiOBr/RGO. was successfully prepared by combining graphene oxide (GO) with BiOBr. The structure, morphology, elemental composition and optical properties of the catalyst were characterized by XRD,SEM,FT-IR,DRS,PL. The photocatalytic activity of BiOBr/RGO under visible light was investigated by using methylene blue as a model. The reaction mechanism was discussed: the photoelectron of BiOBr was easily captured by graphene, and the photoabsorption ability of the material was significantly changed by the deposition of graphene. Thus, the separation of photogenerated electron-hole pairs was promoted, and the efficiency of photocatalytic reaction was improved.
【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
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