Cu掺杂纳米TiO2光催化还原CO2实验研究

利用溶胶凝胶法制备不同掺杂量的CuO-TiO₂纳米粉体,采用热重差热分析仪（TG-DTA）,X射线衍射仪（XRD）,场发射扫描电镜（FSEM-EDX）等手段对其进行表征;在波长为253.7nm的紫外灯照射下,进行CO₂光催化还原实验研究,探究CO₂光催化资源化利用可行性,。结果表明,溶胶凝胶法制备所得CuO掺杂TiO₂纳米粉体,粒径大小在20～30 nm之间;CO₂光催化还原主要产物为甲醇,掺杂量为5%（质量分数）CnO-TiO₂纳米粉体催化效果最好,反应10 h后得到甲醇产量为27mg·（g-cata）^-1;随着反应时间的增加,产物中甲醇含量也逐渐增加。     

压力对纳米CoFe2O4/SiO2复合材料结构的影响

 采用溶胶-凝胶工艺和高温高压实验技术,制备了纳米CoFe₂O₄/SiO₂复合材料。利用X射线衍射仪、扫描电子显微镜和振动样品磁强计,对样品的结构、微观形貌和磁性进行了研究,并对CoFe₂O₄中阳离子的占位情况进行了讨论。结果表明,随着处理压力的升高,样品的晶粒尺寸增大,晶格常数减小,比饱和磁化强度增大。通过计算结果可以推断,压力的升高导致CoFe₂O₄中的部分Fe³⁺从A位移向了B位,而部分Co²⁺则从B位移向了A位。     

Eu3+掺杂Gd2W2O9和Gd2（WO4）3纳米荧光粉发光性质研究

采用共沉淀法制备了不同Eu3+掺杂浓度的Gd2W2O9和Gd2(WO4)3纳米发光材料.通过对纳米材料样品的X射线衍射谱(XRD)和场发射扫描电镜(FE-SEM)照片的观察和分析,对样品的结构和形貌进行了表征.测量了各样品的发射光谱、激发光谱,计算了各样品的部分J-O参数和Eu3+5D0能级量子效率,绘制了不同基质中Eu3+发光的浓度猝灭曲线,对Eu3+掺杂的Gd2W2O9和Gd2(WO4)3纳米发光材料的光致发光性质进行了研究.实验结果证明,与较常见的Gd2(WO4)3:Eu一样,Gd2W2O9:Eu中Eu3+5D0→7F2跃迁的红色发光也能被395nm和465nm激发光有效激发,具有近紫外(蓝光)相对激发效率高,猝灭浓度大的优点,有潜力成为高效的近紫外(蓝光)激发白光LED用红色荧光粉材料.     

Mg2(BH4)2(NH2)2脱氢机理的理论研究

对Mg₂(BH₄)₂(NH₂)₂的脱氢机理展开系统的理论研究发现相对于分子内的脱氢过程,分子间的脱氢过程在热力学和动力学方面都是比较有利的. Mg₂(BH₄)₂(NH₂)₂脱氢过程的第一步是BH₄^-中的B-H^δ-和NH2-中     

纳米SiO2复合对Mg3Sb2基材料热电性能的影响

Mg₃(Sb,Bi)2基热电材料由于其优异的热电性能和较低的成本近来受到广泛的关注.本研究通过将纳米SiO₂复合进成分为Mg_3.275Mn_0.025Sb_1.49Bi_0.5Te_0.01的基体相中,考察其热电输运性能的变化及机制.结果表明,当SiO₂复合进Mg₃Sb₂基材料中时,由于引进大量的微小晶界,能有效地散射声子,促使晶格热导率降低,优化热输运性能,如SiO₂体积含量为0.54%时,室温时热导率由复合前的1.24 W/(m·K)降至1.04 W/(m·K),降幅达到15%;同时其对电子也产生强烈的散射作用,导致迁移率和电导率大幅下滑,结果表现为近室温区功率因子剧烈衰减,恶化了电输运性能.电性能相对于热性能较大降低幅度使得材料在整个测试温区的热电优值没有得到改善.纳米SiO₂作为Mg₃Sb₂     

多孔TiO2/Al/SiO2纳米复合结构的紫外光吸收特性研究

在SiO₂玻璃衬底上用脉冲激光沉积(PLD)技术，分别沉积Ti和Ti/Al膜，经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构. 其中TiO₂薄膜上的微孔阵列高度有序，分布均匀. 实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响. 结果表明：无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在27     

多孔TiO2/Al/SiO2纳米复合结构的紫外光吸收特性研究

在SiO₂玻璃衬底上用脉冲激光沉积(PLD)技术,分别沉积Ti和Ti/Al膜,经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构. 其中TiO₂薄膜上的微孔阵列高度有序,分布均匀. 实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响. 结果表明：无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在27 关键词： 2薄膜')" href="#">多孔TiO₂薄膜 阳极氧化 紫外光吸收     

中空TiO2纳米球的制备

报道了一种新的无机模板法合成中空的TiO₂纳米球,该法以TiCl₄为钛源,中空Sb₂S₃微球为模板,利用TiCl₄水解产生的TiO₂沉积在模板的表面,同时产生的HCl消蚀Sb₂S₃,一步制备中空纳米材料。     

纳米CaF2和纳米Ca0.75La0.25F2.25的结构对离子电导率的影响

用惰性气体蒸发和真空原位加压方法制备了两种具有清洁界面的纳米离子固体CaF₂(平均粒度为16nm)和Ca_0.75La_0.25F_2.25(平均粒度为11nm),在31℃至530℃详细测量了其复阻抗谱。结果表明:1)在300—530℃两种纳米离子导体都很好地遵从Arrhenius方程式;2)纳米CaF₂的离子电导率比多晶CaF₂约高1个数量级、比单晶CaF₂     

In2O3纳米微粒非线性光学特性

用Z扫描技术研究了In₂O₃纳米微粒有机溶胶和水溶胶的三阶非线性光学特性,发现表面修饰能明显提高In₂O₃纳米微粒的非线性响应.讨论了表面偶极效应对In₂O₃纳米微粒非线性的影响. 关键词：     

三元异质结构Ag-Bi2MoO6/BiPO4光催化剂高效降解苯酚红

多组分复合体系有利于电荷的有效分离,减少电子空穴对的复合几率。通过低温液相法首次合成Ag-Bi₂MoO₆/BiPO₄三元异质结构光催化剂。利用XRD、SEM、EDX及XPS等技术对样品进行了表征。结果表明,Ag纳米粒子光照积累在Bi₂MoO₆/BiPO₄的表面,通过表面等离子共振增加对可见光的吸收,同时作为电子受体促进了光生电子的转移。Ag、BiPO₄和Bi₂MoO₆形成三元异质结构有效地抑制了光生电子空穴对的复合。Ag-Bi₂MoO₆/BiPO₄表现出优异的光催化性能,其光催化活性较BiPO₄、Bi₂MoO₆和Bi₂MoO₆/BiPO₄样品有较大提高。并且对Ag-Bi₂MoO₆/BiPO₄三元异质结构的光催化机制进行了讨论。光催化过程中反应活性物种捕获实验结果表明h⁺和O₂^·-是主要的活性基团.     

Photoelectrocatalytic degradation of organic contaminants at Bi2O3/TiO2 nanotube array electrode

In the current work, TiO₂ nanotube array was prepared via electrochemical anode method. Then the Bi₂O₃ nanoparticles were deposited onto the TiO₂ nanotube array via dip-coating method from an amorphous complex precursor. The crystal structures were characterized via X-ray diffraction analysis. Their surface textures were observed via electron-scanning microscope. The prepared composite array electrode exhibited high photoelectrocatalytic activities towards degrading organic contaminants under visible light irradiation. High photoelectrocatalytic activities were also exhibited under UV light irradiation. The catalytic mechanism was discussed based on the analysis of electrochemical and degradation kinetics results. It is suggested a P (Bi₂O₃)-N (TiO₂) junction was formed to increase the catalytic activates. The stability of the electrode materials was confirmed finally.     

网状钼酸铋的可见光催化活性

采用无助剂、无模板的水热法成功合成网状Bi₂MoO₆. pH值对这一形貌的形成起重要作用. 所制备的网状Bi₂MoO₆样品表现出优异的可见光催化活性,其光催化活性比固相法合成的块状Bi₂MoO₆样品高得多.     

圆盘状Bi2WO6-BiPO4异质结的水热合成及光催化性能 (cited: 1)

采用水热法制备Bi₂WO₆-BiPO₄异质结光催化剂．利用模拟太阳光照射下的罗丹明B降解实验评价了Bi₂WO₆-BiPO₄复合物的光催化性能．结果表明,Bi₂WO₆-BiPO₄光催化活性比Bi₂WO₆和BiPO₄高得多．当Bi₂WO₆与BiPO₄的摩尔比为1:1时复合光催化剂对罗丹明B的降解率最高．Bi₂WO₆-BiPO₄催化活性增强主要归结为两者之间形成了有效的异质结结构,其内建电场能够促进光生载流子的分离．同时,Bi₂WO₆的加入增强了其对可见光的吸收．研究表明O₂· ^-和h⁺在光催化降解过程中是主要的活性物种     

铈和磷钨酸共掺杂纳米二氧化钛中空纤维的制备及其光催化活性

以棉花纤维为模板,以钛酸四正丁酯、硝酸铈铵和磷钨酸为原料采用模板法制备了一系列铈和磷钨酸共掺杂的、具有中空纤维结构的TiO₂光催化材料, 利用扫描电子显微镜、X射线衍射、BET和紫外-可见光谱等技术对其形貌、晶体结构及表面结构、光吸收特性等进行了表征. 以苯酚溶液的光催化降解为模型反应,考察了不同掺杂量的样品在紫外和可见光下的光催化性能. 结果表明,用模板法制备的TiO₂纤维材料具有中空结构,共掺杂的TiO₂纤维在紫外和可见光条件下较纯TiO₂纤维和单掺杂TiO₂纤维对苯酚溶液具有更好的光催化降解效果, 且铈和磷钨酸的掺杂量显著影响该纤维材料的催化性能;当铈掺杂量为0.3mol%和磷钨酸掺杂量为2mol%,在500 oC焙烧2 h所得中空纤维材料的催化性能最佳,4 h即可使苯酚溶液的降解率达98.5%;重复使用4次仍可使苯酚溶液的降解率保持在87%以上,且该催化剂材料易于离心分离去除.     

Photocatalytic Activity of N-doped TiO2 Photocatalysts Prepared from the Molecular Precursor (NH4)2TiO(C2O4)2

用不同温度控制分解草酸氧钛铵制备N掺杂TiO₂光催化剂．利用XRD、IR、热分析、N₂吸-脱附等温线、XPS、紫外可见漫反射光谱和SEM表征了N-TiO₂光催化剂的结构．400～600 oC焙烧的N-TiO₂光催化剂为纯锐钛矿相,而700 oC焙烧的N-TiO₂光催化剂为锐钛矿和金红石混合相．N掺杂在TiO₂的间隙位使锐钛矿相TiO₂带隙变窄．在光降解甲基橙的反应中,600和400 oC焙烧的N-TiO₂催化剂分别在紫外光和全波长光照射下有最好活性;700 oC焙烧的N-TiO₂催化剂无论在紫外光和全波长光下都表现出最好的比活性,即最高的光量子效率,这可以归因于700 oC焙烧的N-TiO₂光催化剂良好的结晶程度和锐钛矿-金红石异相结的存在．     

Fabrication, characterization and photoelectrochemical properties of Fe2O3 modified TiO2 nanotube arrays

TiO₂ nanotube (NT) arrays modified by Fe₂O₃ with high sensibility in the visible spectrum were first prepared by annealing anodic titania NTs pre-loaded with Fe(OH)₃ which was uniformly clung to the titania NTs using sequential chemical bath deposition (S-CBD). The photoelectrochemical performances of the as-prepared composite nanotubes were determined by measuring the photo-generated currents and voltages under illumination of UV-vis light. The titania NTs modified by Fe₂O₃ showed higher photopotential and photocurrent values than those of unmodified titania NTs. The enhanced photoelectrochemical behaviors can be attributed to the modified Fe₂O₃ which increases the probability of charge-carrier separation and extends the range of the TiO₂ photoresponse from ultraviolet (UV) to visible region due to the low band gap of 2.2 eV of Fe₂O₃.     

10BaF2:NaF, Na3AlF6/TiO2 composite as a novel visible-light-driven photocatalyst based on upconversion emission

A rare-earth free upconversion luminescent material, 10BaF2：NaF, Na3AIF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light （550 nm-610 nm） into ultraviolet light （290 nm 350 nm）, and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF2：NaF, Na3AIF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation （λ〉 515 nm）. The results show that 10BaF2：NaF, Na3AIF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 μmol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF2：NaF, Na3AIF6/TiO2 is proposed.     

Effects of surface-modification with Bi2O3 on the thermal stability and photoinduced charge property of nanocrystalline anatase TiO2 and its enhanced photocatalytic activity

Bi₂O₃ surface-modified TiO₂ nanoparticle has been synthesized by sol-hydrothermal processes, followed by post-treatment with an appropriate amount of bismuth nitrate solution, and also characterized by XRD, Raman, BET, TEM, FT-IR, XPS, UV-vis DRS and SPS techniques. The effects of the surface-modification with Bi₂O₃ on the thermal stability, photoinduced charge separation and photocatalytic activity for degrading rhodamine B (or phenol) under ultraviolet (or visible) irradiation are investigated in detail, along with their relationships and the activity enhancement mechanisms are also suggested. The results show that the modification with Bi₂O₃ can improve the thermal stability of the as-prepared anatase crystallites, consequently enhancing the anatase crystallinity so as to promote the photoinduced charge separation. And the modification with Bi₂O₃ also extends the optical response range. It can be concluded that the activity enhancement of surface-modified TiO₂ is mainly attributed to the increase in the photoinduced charge separation rate and to the extent of the optical response range, compared with un-modified ones. Moreover, the inhibition phase transformation mechanism related to Bi₂O₃ is suggested.     

Preparation and characterization of visible light responsive Fe2O3-TiO2 composites

In this study we present the effects of iron oxide (Fe₂O₃) on titanium dioxide (TiO₂) in synthesising visible-light reactive photocatalysts. A Fe₂O₃-TiO₂ composite photocatalyst was synthesized from Fe₂(SO₄)₃ and Ti(SO₄)₂ by a ethanol-assisted hydrothermal method. The preparation conditions were optimized through the investigation of the effects of hydrothermal temperature and time as well as molar ratio of Ti to Fe on the photocatalytic activity. The visual, physical and chemical properties of the Fe₂O₃-TiO₂ composites were investigated. The results showed that α-Fe₂O₃ and anatase TiO₂ were present in the composites. The Fe₂O₃-TiO₂ synthesized under optimum condition consisted of mesoporous structure with an average pore size of 4 nm and a surface area of 43 m²/g. Under visible and solar light irradiation, the photocatalytic activity of optimized sample was significantly higher than that of pure TiO₂. This sample led to a photodegradation efficiency of 90% and 40% of auramine under visible light and solar light, respectively.