可见光下掺N附Ag纳米TiO_2的光催化降解甲基橙

采用溶胶–凝胶法制备纯TiO_2和掺氮TiO_2纳米颗粒(N-TiO_2),然后通过光催化还原在其表面附Ag,得到表面附Ag的纳米TiO_2(即Ag/TiO_2)和掺N附Ag纳米TiO_2(即Ag/N-TiO_2),利用X射线衍射(XRD)、场发射扫描电镜(FE-SEM)、光致发光光谱仪(photoluminescence spectroscopy,PL)、X射线光电子能谱(XPS)以及紫外可见漫反射光谱分析(UV-VIS DRS)对TiO_2及其掺杂改性后的组成和结构、光吸收性能以及可见光下对甲基橙溶液的光催化活性等进行表征。结果表明,所有样品均为锐钛矿型,Ag/TiO_2的平均晶粒度为20.4 nm;N以替代型N-Ti-O、间隙型Ti-O-N(或氧化态Ti-O-N-O)的形式存在于晶格中,银以Ag0形式附着在TiO_2表面;N掺杂抑制TiO_2晶粒的生长,并抑制光生电子与空穴的复合,从而促进TiO_2对可见光的吸收;表面附Ag对TiO_2晶格没有明显影响,但在450~580 nm可见光区产生强烈的表面等离子吸收带并延长至近红外区。TiO_2及其掺杂改性后对甲基橙的光催化效果为Ag/N-TiO_2Ag/TiO_2N-TiO_2TiO_2(或Degussa P25),Ag/N-TiO_2在可见光下对甲基橙(p H=3)进行光催化降解,150 min时降解率达到95%。     

Cu/Ag掺杂TiO_2包覆SiO_2纳米复合材料的结构与光催化性能

采用溶胶-凝胶法制备包覆层厚度约为12 nm的高分散性TiO_2包覆SiO_2(TCS)复合粉末。在此基础上,合成光催化效率显著提高的Cu和Ag掺杂TCS光催化剂。利用X射线衍射仪、X射线光电子能谱仪、紫外-可见分光光度计和光催化降解甲基橙测试等,系统研究包覆和掺杂对TiO_2结构及光催化活性的影响规律和相关作用机制。结果表明,TiO_2与SiO_2的界面可能以Ti—O—Si化学键联结,并通过影响TiO_2的结晶过程而抑制TiO_2晶粒的长大。通过控制实验条件得到了性能优异的Cu_2O-TiO_2-SiO_2复合粉末,Cu掺杂的作用机制可理解为Cu_2O半导体对TiO_2的修饰,光催化活性的提高与氧空位和Cu_2O有关。相比较,Ag掺杂对TiO_2的禁带宽度影响不大,但吸光强度有较大提高。当Ag掺杂量为1.0%时,光催化降解甲基橙效率达到95.7%。     

自组装TiO_2分级结构材料的制备及性能研究

采用水热法合成了梭形TiO_2分级结构材料,运用扫描电镜(SEM)、X射线衍射(XRD)对其形貌、结构进行了表征和分析,考察了水热温度、乙酸加入量对TiO_2样品的影响,并研究了其光催化性能。结果表明,所制备TiO_2分级结构材料为锐钛矿相,是由纳米晶自组装形成的梭形结构,水热温度和乙酸加入量对TiO_2形貌影响不大,但对TiO_2晶粒大小有影响。以甲基橙溶液为模拟污染物研究TiO_2样品的光催化性能,在紫外光照射下,表现出良好的光催化活性。     

铈掺杂TiO2光催化降解甲基橙的研究

采用溶胶-凝胶法制备纯的及掺杂不同量Ce的TiO2纳米粒子,利用UV-Vis漫反射光谱及XRD等对所制备样品进行表征和解释,以高压汞灯为光源,甲基橙水溶液的脱色为模型反应,研究了CeO2/TiO2的光催化降解反应活性.实验发现掺杂Ce的TiO2纳米粒子反射光谱特性向可见光方向红移到了500 nm;掺杂Ce的TiO2纳米粒子比纯的TiO2纳米粒子对光的吸收率高、吸收能力强;掺杂的Ce4+仅有少量进入TiO2晶格中,而大部分的Ce4+没有进入TiO2晶格中,而是以小团簇的CeO2形态均匀地分散在TiO2纳米粒子中或者是覆盖在其表面上,说明掺杂Ce能提高TiO2光催化反应活性,且掺杂Ce量有最佳值.实验结果表明在TiO2中掺杂Ce的摩尔百分含量为2%,甲基橙起始浓度为20 mg·L-1,CeO2/TiO2用量为0.400 g,双氧水用量为5.88 mmol·L-1,pH值为6.4时,光照8 h,甲基橙的脱色率可达96.8%.     

TiO_2-ZnO复合材料的制备及光催化性能研究

以二氧化钛(TiO_2)和氧化锌(ZnO)粉体为前驱体,通过固相法合成了不同ZnO摩尔分数(x)的TiO_2-ZnO复合粉体材料。复合材料的结构、形貌及性能分别用X射线衍射仪(XRD)、扫描电镜(SEM)和紫外-可见(UV-Vis)吸收光谱仪等仪器进行了表征,同时研究了不同ZnO摩尔分数和煅烧温度对TiO_2-ZnO复合材料结构和形貌的影响及复合材料对甲基橙的光催化活性。结果表明,煅烧温度对复合材料的结构和形貌影响很大。当t=600℃,x=0.440时,TiO_2-ZnO粉体由纤锌矿结构的ZnO、锐钛矿结构的TiO_2和少量的Ti_3Zn_3O_(0.5)共同组成,且界面颗粒接触紧密。ZnO和TiO_2的复合不仅提高了复合材料在紫外区的吸收,而且也增强了其在可见光区的吸收。另外,TiO_2-ZnO复合材料(x=0.440)对有机染料甲基橙有非常好的光催化活性,在紫外光照射120 min后甲基橙的降解率高达95.7%。     

镧、银离子掺杂对TiO_2光催化活性的影响

以钛酸四丁酯为原料,采用溶胶-凝胶法制备了纯的TiO2纳米粒子和掺杂镧、银离子并且浓度分别为2%,5%的TiO2纳米粒子。利用XRD和UV-VIS对其进行表征,且在日光条件下,以甲基橙的光催化降解为模型反应,考察了纯的TiO2纳米粒子及不同镧、银离子掺杂浓度下的TiO2纳米粒子光催化活性。结果表明,在掺杂镧、银离子后,TiO2的本征吸收光谱比未经掺杂的出现不同程度的红移,在氧化剂的协同作用下使得甲基橙的降解效率有明显提高。     

La掺杂TiO_2的制备及光催化处理石化二级出水的研究

采用溶胶-凝胶法制备了稀土La掺杂TiO_2纳米粉末,利用X射线衍射(XRD),紫外-可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)和荧光光谱(PL)等分析方法对所制备样品进行表征;以亚甲基蓝和石化二级出水作为降解对象,研究了La掺杂TiO_2样品的光催化性能。表征结果显示,本实验所制备的TiO_2样品均为锐钛矿晶型;稀土La掺杂可以使样品的晶粒尺寸由25 nm减小为15 nm;同时可改善样品的团聚现象;并可促进样品对可见光的吸收;此外还具有降低电子-空穴的复合,提高TiO_2量子效率的作用。光催化降解亚甲基蓝实验结果显示,当La掺杂含量为0. 50%时,样品的光催化性能最佳;优选0. 50%La-TiO2对石化二级出水进行光催化降解反应,结果显示光催化反应180min时,二级出水中的化学需氧量(COD)和UV254的降解率分别可达55%和70%以上;且经过3次回用后降解率未明显下降,说明本实验所制备的实验样品具有良好稳定的光催化性能,这为光催化深度降解石化二级出水工业应用提供了可能。     

金属离子掺杂对离子液辅助制备纳米TiO_2性能的影响

以过渡金属(Cr、Fe、Ni和Zn)掺杂为手段,以溶胶凝胶为制备方法,以离子液2—羟基咪唑甲酸盐为微观结构调控试剂,制备了TiO_2纳米粒子。将样品备好后,在500℃的条件下进行煅烧处理,用BET、XRD、DRS等手段进行结构表征,以酸性蓝92为模拟污染物对其光催化性能进行测定。研究结果表明,经过渡金属掺杂后的TiO_2纳米颗粒比纯TiO_2具有更高的比表面积和更小的粒径尺寸。过渡金属的掺杂使TiO_2的吸收光谱向可见光的方向移动。在紫外灯照射下,水溶液中酸性蓝92的光降解结果为:过渡金属离子的存在使TiO_2纳米颗粒的光催化活性得到了明显增强。     

水热法制备氮、铁共掺杂TiO_2研究

以钛酸正丁酯为前躯体,硝酸铵和九水硝酸铁为氮、铁掺杂源,利用水热法制备了氮、铁共掺杂TiO2粉体。采用XRD、FE-SEM、EDS、BET、FT-IR等手段对所制备粉体进行了表征。结果显示:共掺杂TiO2粉体为锐钛矿型,呈球状,粒径为9.2 nm,较高的比表面积201 m2/g。对甲基橙溶液的光降解实验结果表明,在350W氙灯(模拟自然光)条件下,共掺杂的TiO2对于甲基橙的降解率为96.4%,光催化活性高于P25。在太阳光下,光照4 h,对甲基橙的降解率达到84.5%。     

Ru负载TiO_2纳米管阵列的制备及其光电催化性能

结合阳极氧化法和脉冲沉积法合成了管径约40～70 nm、管壁厚约10 nm、管长约1μm、管壁上附着Ru纳米颗粒的TiO_2纳米管光催化剂(Ru/TiO_2),实现了金属Ru纳米颗粒在TiO_2纳米管表面的均匀负载。研究了RuCl_3浓度和煅烧温度对TiO_2纳米管的微观结构、光吸收特性及光催化活性的影响。结果表明:Ru的负载使Ru/TiO_2纳米管的光学带隙值有所减小,光响应阈值发生红移;锐钛矿相TiO_2与少量金红石相TiO_2可形成异质结,纳米Ru可俘获光生电子,两者都可促进光生电子-空穴对的分离,从而提升降解效率;另外,外加偏压也可促进光生电子-空穴对的分离,从而进一步提升降解效率。当脉冲沉积液中RuCl_3浓度为0. 05 mol·L~(-1),经600℃煅烧后的Ru/TiO_2纳米管阵列的光催化活性最好,对甲基橙降解1 h,紫外光下的光催化和光电催化分解比例由纯TiO_2纳米管的38. 6%和48. 5%提升至52. 0%和70. 5%,可见光下的光催化和光电催化分解比例由纯TiO_2纳米管的7. 1%和17. 2%提升至36. 3%和75. 2%。     

纳米二氧化钛粉体的光催化性能

以紫外灯为光源,采用TiO_2悬浮体系,利用分光光度法,研究了各种实验条件对光催化效果的影响。结果表明:光强、甲基橙的初始浓度、TiO_2的浓度和晶型、溶液pH以及掺杂离子等对降解效率都有较大的影响。     

Preparation of TiO2/Hydroxyapatite Composite and Its Photocatalytic Degradation of Methyl Orange

A TiO2/hydroxyapatite composite (Ti-HAP) was prepared by a hydrothermal method with hydroxyapatite and titanium sulfate and tested for photocatalytic degradation of methyl orange with an 8?W ultraviolet (UV) lamp irradiation. The properties of Ti-HAP were characterized by X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy (FT-IR) analysis. The effect of the Ti/(Ca+Ti) mole ratio on the photocatalytic degradation efficiency of methyl orange by Ti-HAP and the photocatalytic degradation dynamics were investigated. The results show that the addition of Ti slightly changes the structure of HAP. A higher Ti/(Ca+Ti) mole ratio results in the generation of anatase in Ti-HAP and higher removal efficiency of methyl orange by Ti-HAP under UV irradiation. The removal efficiency decreases with the initial content of methyl orange increasing from 10–200??mg/L. The photocatalytic degradation process of methyl orange by Ti-HAP and HAP follow the Langmuir-Hinshelwood kinetics model.     

Ag/AgCl复合粉末的制备及光催化性能研究

AgCl光催化剂可以有效避免纳米TiO_2只对紫外光响应造成的缺陷和不足。围绕Ag/AgCl复合粉体的制备及其对催化降解有机污染物的性能进行研究,采用四种不同的方法制备了Ag/AgCl复合粉体,在波长λ420 nm的可见光下考察了Ag/AgCl复合粉体对甲基橙的降解能力,并探讨了其催化机理。结果发现,催化剂的活性与复合粉体样品的形貌结构有很大关联。以AgNO_3作为Ag源,利用乙醇将部分AgNO_3还原为纳米银颗粒,并利用聚乙烯吡咯烷酮(PVP)作为高分子保护剂制备出的Ag/AgCl复合粉体表现出良好的可见光催化活性和稳定性,在20 min内几乎将甲基橙完全降解,该光催化剂对甲基橙的一级降解反应常数为4.99×10~(-2)。     

Photocatalytic degradation of pesticide residues with RE³⁺-doped nano-TiO₂

The photocatalytic degradation effects of carbofuran solution under concentration of 0.2,0.4,0.8 g/L Re3+-doped nano-TiO2 were studied.The highest degradation rate of 54.89% was obtained after 4 h degradation when the concentration of nano-TiO2 was 0.4 g/L.Then field trials of photocatalytic degradation with suspension nano-TiO2 were conducted.The photocatalytic degradation effect of organic phosphorus and carbamate pesticides in tomato leaves and soil with different concentratio catalyst(0,0.2,0.4,0.6,0.8 g/L) were studied.The results showed that nano-TiO2 could significantly increase photocatalytic degradation rate of pesticide residues in tomato leaves and soil.Pesticide residues degradation rate could be increased by 20%-30% on the tomato leaves and 15%-20% in soil,and the best concentration of photocatalytic degradation was 0.2-0.4 g/L.     

Photocatalytic activity of Eu3＋-doped ZnO nanorods synthesized via microwave assisted technique

The doped ZnO nanorods as a photocatalyst with different Eu contents were prepared by microwave assisted method and they were characterized by means of X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),UV-Vis spectroscopy,surface area Brunauer-Emmett-Teller(BET),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The average crystallite size and band gap energy of Eu-doped ZnO were varied with the Eu content.The XRD pattern of Eu-doped ZnO indicated hexagonal crystal structure with an average crystallite size of 25 nm.The presence of europium with trivalent state and its doping successfully into the crystal lattice of ZnO matrix were confirmed by XPS technique.The photocatalytic activity of Eu-doped ZnO nanorods was evaluated for methyl orange degradation.The photocatalytic experiments showed ～91% degradation of methyl orange over 0.2 mol.% Eu doped ZnO sample within 3 h under UV light(365 nm).     

铈或钕掺杂TiO2光催化陶瓷及其自洁净抗菌性能研究

采用溶胶-凝胶法和浸渍提拉法在陶瓷表面覆盖了Ce或Nd掺杂的TiO2薄膜.稀土掺杂量为Ce/TiO2=0.007,Nd/TiO2=0.003(摩尔比)时,铈或钕掺杂TiO2光催化陶瓷分别对甲基橙的降解率最大.稀土掺杂TiO2光催化陶瓷对大肠杆菌的抗菌率高达99%,较纯TiO2光催化陶瓷的91%更高.     

负载型TiO2/硅藻土复合光催化剂的研究

以四氯化钛为原料采用溶胶-凝胶法制备了负载型TiO2，硅藻土复合光催化剂，并通过XRD，IR，SEM等手段对样品进行了表征。实验中分别以300W高压汞灯和太阳光为光源，研究了硅藻土载体上TiO2负载量不同对甲基橙溶液光催化氧化效果的影响。实验结果表明：复合光催化剂的催化性能随着TiO2负载量增大先提高，而后有所下降，其中以1g硅藻土与1．8ml四氯化钛制备的TiO2，硅藻土复合催化剂光催化活性最高。     

Influence of inorganic anions and organic additives on photocatalytic degradation of methyl orange with supported polyoxometalates as photocatalyst

A novel supported polyoxometalate(POM),phosphotungstic acid immobilized into yttrium-doped TiO2(HPW-Y-TiO2) nano photocatalyst was prepared via sol-gel and impregnation method.The samples were characterized using Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD) and N2 absorption-desorption analysis.The results showed that the supported POM exhibited Keggin structure and anatase phase with large BET surface area.The influences of inorganic anions and organic additives on the photocatalytic degradation of azo dye methyl orange with HPW-Y-TiO2 as photocatalyst under UV light(λ≥365 nm) were investigated.Results showed that inorganic anions Cl-,SO42-,CO32-and NO3-had inhibition effect on the degradation of methyl orange.A great enhancement of degradation rate was obtained while H2O2 and ethyl alcohol were applied.The degradation rates improved with the increase of H2O2 concentration.The optimum additive amount of ethyl alcohol was 0.5 mol/L.The possible mechanisms of the effects of additives on methyl orange degradation were discussed.