Theoretical calculation and experimental study of influence of oxygen vacancy on the electronic structure and hemocompatibility of rutile TiO2

In this work, the relationship between electronic structure and hemocompatibility of oxygen deficient rutile TiO_2?x was studied by both theoretical calculation and experimental study. Based on the local density functional theory, first-principals method was performed to calculate the electronic structure of rutile TiO₂ with different oxygen vacancy concentration. In the range of less than 10% of (or equal) physically realistic O vacancy concentration, the band gap of rutile TiO₂ increases with increasing O vacancy concentration, leading the TiO₂ changes from a p-type to an n-type semiconductor. The valance band of TiO₂ is predominated by O 2p orbital, while the conduction band is occupied by Ti 3d orbital for different O vacancy concentration. The O vacancy results in the occupation of electrons at the bottom of conduction band of TiO₂, and the donor density increases with increasing O vacancy concentration. When materials come in contact with blood, the n-type semiconductor feature of oxygen deficient TiO_2?x with the bottom of conduction band occupied by electrons would prevent charge transfer from fibrinogen into the surface of materials, thus inhibiting the aggregation and activation of platelets, therefore improving the hemocompatibility of rutile TiO_2-x .

     

氧空穴对二氧化钛/磷酸银光催化活性的影响机制

采用磷酸银与具有可见光吸收能力的TiO_2基光催化剂相复合的方法,对带有氧空穴的二氧化钛(TiO_2-OV)的复合磷酸银光催化材料的性能进行了研究.采用光处理法成功制备出了具有可见光吸收能力的氧空穴二氧化钛材料,利用化学吸附法成功制备出了磷酸银/氧空穴二氧化钛复合光催化剂.透射电镜结果显示,磷酸银纳米颗粒均匀分散于氧空穴二氧化钛表面,形成结构完美的复合光催化剂;光催化降解罗丹明B实验结果表明,所制备的磷酸银/氧空穴二氧化钛复合光催化剂的光催化活性明显优于磷酸银光催化材料.     

TiO2/ML-Ti3C2复合纳米材料的制备及其光催化性能

通过水热技术在二维(2D)多层材料Ti_3C_2 (multi-layer Ti_3C_2, ML-Ti_3C_2)的表面及层间原位晶化和生长锐钛矿相TiO_2纳米球,制备出TiO_2/ML-Ti_3C_2复合纳米材料。采用XRD、SEM、氮吸附等表征技术对TiO_2/ML-Ti_3C_2纳米复合材料进行分析表征,并以亚甲基蓝(MB)为模拟污染物,对纯TiO_2和TiO_2/ML-Ti_3C_2复合纳米材料的光催化性能进行了评价。实验结果表明,两种材料的耦合抑制了Ti O_2中光生电子-空穴对的湮灭,延长了复合光催化剂中载流子寿命,拓宽了复合材料的光谱响应范围。在紫外光照射下,以TiO_2/ML-Ti_3C_2复合纳米材料为光催化剂,200 mg/L的MB溶液在20 min内几乎完全脱色,降解率为98.98%。TiO_2/ML-Ti_3C_2纳米复合材料的光催化性能优于纯TiO_2和Ti_3C_2, Ti_3C_2优异的电子传输能力和超强的吸附性能优化了TiO_2的光催化性能。本研究为使用光催化技术处理废水提供了一种新的思路,具有一定的实际应用前景。     

热处理对TiO2/AC电极材料结构及电化学性能的影响

为了研究不同热处理温度对Ti O2/AC电极材料结构及电化学性能的影响,采用溶胶-凝胶法制备该电极材料,通过扫描电子显微镜(SEM)、热重分析仪(TG-DTG)、比表面积及孔径分析仪(BET)、X射线衍射光谱仪(XRD)和电化学工作站对其微观结构和电化学性能进行表征分析.结果表明:热处理使Ti O2呈絮状或颗粒状附着于活性炭表面及孔道中;随着热处理温度升高,Ti O2/AC比表面积先增大后减小,晶型由锐钛型逐渐向金红石型转变,晶粒尺寸也逐步增大,比电容值先增大后减小;当热处理温度为450℃时,Ti O2/AC电极材料的晶型呈锐钛型且晶粒尺寸适中、有效比表面积最大、电化学性能最优.     

二氧化钛光催化剂掺杂改性的研究进展

半导体材料TiO2作为光催化剂得到了广泛的研究和应用.介绍了TiO2光催化反应机理以及光催化剂掺杂改性的研究进展,包括金属离子、非金属以及金属/非金属共掺杂,并且指出了TiO2光催化剂改性的研究热点和研究方向.     

纳米TiO2颗粒与腐殖酸和SDBS的相互作用机制

为保障水环境生态安全性及纳米技术的可持续发展,研究了纳米Ti O2颗粒与腐殖酸(HA)和十二烷基苯磺酸钠(SDBS)的相互作用,考察了p H、离子浓度对其相互作用的影响.结果表明,腐殖酸和十二烷基苯磺酸钠均会抑制纳米颗粒的聚集,增强颗粒的迁移能力.p H和离子浓度对相互作用有显著的影响.当溶液的p H接近等电点时,纳米颗粒表面带正电荷,因电荷屏蔽效应,HA和SDBS在颗粒表面的吸附量增大;随着IS的增加,由于双电层压缩作用,HA及SDBS在纳米Ti O2表面的吸附量也不断增加.最后,讨论了纳米Ti O2颗粒与HA及SDBS的相互作用机制,即可分为聚集、接近和强相互作用3个步骤.同时比较了HA和SDBS与纳米Ti O2颗粒相互作用机制的不同.     

Mechanism and behaviors of Cr3+-doped TiO2

TiO₂ powder and TiO₂ thin film on the surface of glazed ceramic tile were prepared by sol-gel method. The influences of different doping Cr³⁺ concentration on the photocatalytic activity of TiO₂ were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO₂ powder and film. The results indicate that photocatalytic activity of doping Cr³⁺-TiO₂ thin film is higher than that of powder, and the interaction between Cr³⁺-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr³⁺-doped energy level in TiO₂ is 0.62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr³⁺ dopant energy level, the semiconductor energy level model of Cr³⁺ in TiO₂ powder and thin film were established, and the doping mechanisms of Cr³⁺-doped in TiO₂ powder and thin film were analyzed. Foundation item: Project (20466001) supported by the National Natural Science Foundation of China     

Fe掺杂锐钛矿型TiO_2光催化剂第一性原理研究

采用了基于密度泛函理论的分子模拟软件Materials Studio的Dmol~3计算模块,对铁(Fe)掺杂锐钛矿型TiO_2光催化剂的超晶胞体系进行了几何结构优化.模拟计算过程中,使用广义梯度近似的方法处理交换关联能,得到了TiO_2在掺杂Fe前后的能带结构和电子态密度的变化状况,为光催化剂的选择与制备提供了理论依据.     

Review:Nanostructured TiO2 for Enhanced Photocatalytic Property by Glancing Angle Deposition Method

物理气相沉积GLAD法在二氧化钛光催化剂的应用

双爽¹,谢拯^1,2,张政军³

（1.清华大学 新型陶瓷与精细工艺国家重点实验室（材料科学与工程学院）,北京 100084;2. 西安高新技术研究所, 西安 710025;3. 清华大学 先进材料教育部重点实验室（材料科学与工程学院）,北京 100084）

创新点说明：

1）通过气相沉积的物理方法,制备垂直或倾斜生长的纳米阵列作为光催化剂,提高催化剂回收效率,减少二次污染;

2）运用掺杂、修饰以及复合其他材料的方法,拓展二氧化钛在可见光范围的利用;

3）通过表征手段分析,分析内在光催化效率提高机理。

研究目的：

通过多种方法,提高气相沉积GLAD法制备的二氧化钛在可见光范围的利用率,分析催化反应提高机理。

研究方法：

磁控溅射、电子束蒸镀、原子层沉积

结果：

1）通过气相物理沉积GLAD方法,制备了垂直或倾斜生长的纳米阵列作为光催化剂,提高回收效率,减少二次污染;

2）利用掺杂、修饰以及复合其他材料的方法,提高二氧化钛在可见光范围的利用率;

3）通过表征手段分析,分析内在光催化效率提高机理。

结论：

1）实现了在特定基底生长纳米阵列光催化剂的制备,提高回收效率减少二次污染;

2）使用化学方法复合窄带隙硫氧化物、贵金属及石墨烯提高催化剂在可见光范围的利用率,并分析其内在增强机理。

关键词：二氧化钛纳米阵列,倾斜生长阴影效应,带隙匹配

     

沸石负载Mn,N共掺杂TiO2及光催化性能

为提高传统TiO₂光催化剂的可见光催化活性,本文采用溶胶-凝胶法合成了Mn,N共掺杂TiO₂光催化剂,改善了传统TiO₂光生载流子易复合的问题;进一步采用沸石作为载体对改性后的TiO₂样品进行负载,解决了传统光催化剂存在的难分离回收问题,以达到光催化剂可重复使用的目的.借助X-射线衍射仪、扫描电子显微镜、紫外分光光度计、傅立叶变换红外光谱仪等测试手段对Mn,N共掺杂TiO₂光催化剂的结构、元素组成、微观形貌和光催化降解性能进行系统分析与研究.研究结果表明,沸石负载Mn,N共掺杂TiO₂的样品较未改性的TiO₂样品具有更高的光催化降解活性,在可见光照射下,在最优掺杂条件下获得的TiO₂光催化剂在60 min内对孔雀石绿的降解率可达到97%,这主要归因于锰离子掺杂能够对TiO₂光生载流子的复合产生抑制作用,促进光生电荷分离,与此同时氮元素掺杂可有效拓宽TiO₂半导体光催化剂光响应范围.此外,经过5次循环使用后,对孔雀石绿的降解率没有较大程度的减弱,依然能够维持在88%以上,表明沸石负载Mn,N共掺杂TiO₂的样品具有较好的光催化循环稳定性.     

Pd纳米晶修饰TiO2纳米管阵列光电极的制备及性能

为提高TiO₂的可见光催化性能,采用阳极氧化法在Ti箔上原位生成TiO₂纳米管阵列,再利用阴极电沉积法制备了贵金属Pd纳米晶修饰的TiO₂纳米管阵列光电极,并利用扫描电子显微镜（SEM）、X-射线光电子能谱（XPS）及紫外-可见漫反射光谱（UV-vis DRS）对其表观形貌、表面形态及光吸收性能进行表征．结果表明:Pd纳米晶有效地修饰在TiO₂纳米管阵列的表面,且以Pd⁰形式存在．此外,Pd纳米晶修饰明显拓展了TiO₂纳米管阵列的可见光响应范围．以甲基蓝为模型污染物,重点考察阴极沉积电压及沉积时间对其光催化性能的影响．结果表明:阴极沉积电压为-0.8 V、沉积时间为10 min对甲基蓝的光催化降解效果最佳,且符合拟一级反应动力学模型．模拟太阳光下光照120 min对甲基蓝的降解率可达71.4％,是纯TiO₂纳米管阵列光电极的1.5 倍．     

Cu~(2+)/Ce~(4+)-TiO_2可见光催化降解活性艳红X-3B

采用溶胶凝胶法合成了掺杂Cu~(2+)和Ce~(4+)的Ti O2可见光催化剂,用活性艳红X-3B降解脱色为模型反应,结合紫外-可见光谱法、XRD和SEM等表征手段,考察了制备条件与光催化活性的关系.实验结果表明:适量掺杂稀土元素Ce~(4+)较单独掺杂Cu~(2+)能更加有效地提高催化剂在可见光下的催化活性,掺杂后使催化剂的吸收带边位置发生红移,晶型结构为锐钛矿和金红石的混合晶型.掺杂Ce~(4+)量为1.5%时,0.4 g催化剂对30 m L浓度为5 mg/L的活性艳红X-3B模拟印染废水降解率达到61.1%.     

Review: Ferromagnetism in Undoped ZrO2 Thin Films

未掺杂氧化锆薄膜的铁磁性研究

宁帅,张政军（清华大学材料学院）

创新点说明：1,通过不同的物理气相沉积方法,实现了对未掺杂氧化锆薄膜的物相调控;2,发现了未掺杂氧化锆薄膜室温铁磁性对物相结构的依赖性;3,通过缺陷分析表征,发现四方相氧化锆的室温铁磁性主要由氧空位缺陷调控。

目的：未掺杂氧化锆薄膜的制备、物相和缺陷调控以及室温铁磁性研究。

方法：脉冲电子束沉积、直流反应磁控溅射、电子束蒸镀。

结果：1,通过不同的物理气相沉积方法,实现了未掺杂氧化锆薄膜的物相调控;2,发现了未掺杂氧化锆薄膜室温铁磁性的物相依赖性;3,通过缺陷分析表征,发现四方相氧化锆的室温铁磁性主要由氧空位缺陷调控。

结论： 1,制备了不同物相结构的未掺杂的氧化锆薄膜;2,发现了四方相氧化锆薄膜可以在室温下呈现铁磁性;3,四方相氧化锆薄膜中的室温铁磁性主要由氧空位缺陷引起。

关键词：氧化锆薄膜,物相调控,室温铁磁性,氧空位缺陷

     

电合成过氧化氢电催化剂的设计及进展

过氧化氢（H₂O₂）是一种环境友好的高效氧化剂,被广泛应用于医疗、半导体芯片等行业.利用氧还原法（ORR）电化学合成过氧化氢替代传统蒽醌法极具潜力.为了实现这一工艺的商业化,开发具有高活性、高选择性和长期稳定性的2e^-ORR电催化剂迫在眉睫.本文系统地介绍了目前已有金属与非金属类催化剂的研究历程,特别强调表面基团调控策略,并解析了其对还原过程中间体键位结合强度及电子转移路径的影响.重点阐述电子和几何效应、配位杂原子掺杂和非金属基材料活性位点等关键问题,突出了适当的介观结构工程和动力学策略可进一步优化现有催化剂的催化活性和H₂O₂选择性.最后,指出了非金属催化剂活性中心的探索、电解质环境对催化剂的影响及较大输出功率工业设备的设计等方面的挑战,并对电催化合成过氧化氢领域的发展方向提出了展望.     

Simulated Sunlight Irradiation Based Photocatalytic Degradation of Acrylonitrile by Sn-F Co-doped TiO2/SiO2 Nano Powder Catalyst

模拟阳光照射下Sn-F共掺杂TiO2/SiO2纳米粉体催化剂对丙烯腈的光催化降解

李翰良¹,苗诗雨²,邱露¹,Bandna Bharti¹,欧阳峰¹

（1．哈尔滨工业大学（深圳） 土木与环境工程学院, 深圳 518055;

2． 大连理工大学（盘锦） 生命科学与医学学院,辽宁 盘锦 124000）

创新点说明：

光催化降解污染物是一种绿色环保技术,其中F-TiO2/SiO2是本课题组研究比较成熟的技术,现通过进一步Sn-F共掺杂方式使得催化剂活性进一步提升,对光的吸收能力更强。

研究目的：

本研究致力于解决丙烯腈生产废水的光催化降解问题,由于丙烯腈存在碳氮三键,很难被生物降解,且丙烯腈生物毒性很强,常规方法很难达到彻底降解的目的。故本研究通过光催化技术产生强氧化能力的空穴将其氧化。

研究方法：

通过Sn-F共掺杂方式改性F-TiO2/SiO2催化剂,研究不同煅烧温度对其表面特性的影响,并进行XRD,SEM,EDS,XPS,BET,UV-Vis,PL等表征手段研究。

研究结果：

实验结果表明：通过Sn-F共掺杂,提升了光的吸收能力,增大了催化剂的比表面积,不同温度下煅烧均为锐钛矿相,且催化剂的分散性良好,电子-空穴对的分离得到改善,降解丙烯腈的能力比未掺杂前有很大的提高。

结论：

采用溶胶-凝胶法制备了Sn-F-TiO2/SiO2催化剂。在模拟光照条件下降解丙烯腈,评价其光催化活性。系统研究了Sn-F-TiO2/SiO2催化剂对丙烯腈降解的催化活性。Sn-F-TiO2 /SiO2催化剂对丙烯腈的降解率为67.7%。表征结果表明,Sn-F-TiO2/SiO2催化剂晶体尺寸小,颗粒表面小,颗粒疏松,有利于催化剂粉末在反应体系中均匀分散。PL也略有减弱,这意味着光生电子和空穴的复合受到抑制。吸收边发生红移,提高了光的利用率,并提高了光催化活性。XPS结果表明,催化剂晶格中成功掺杂了锡。在反应体系中加入牺牲剂表明,空穴是光催化活性中最重要的活性组分。

关键词：光催化,丙烯腈降解,Sn掺杂,F-TiO2/SiO2

     

Study on method and mechanism for simultaneous desulfurization and denitrification of flue gas based on the TiO2 photocatalysis

Based on the TiO₂ photocatalysis mechanism, a new method of simultaneous desulfurization and denitrification from flue gas was proposed. Preparation of TiO₂ photocatalyst, design of photocatalysis reactor and influencing factors for simultaneous removal of SO₂ and NO, and removal mechanism of SO₂ and NO were studied. After the optimal values of concentration of O₂ in flue gas, the relative humidity of flue gas and the irradiation time in the photocatalysis reactor were used, the efficiencies of removal for SO₂ and NO can be achieved above 98% and about 67%, respectively. According to the results of removal products analysis, the removal mechanism of SO₂ and NO based on TiO₂ photocatlysis can be put forward, namely, SO₂ was oxidized to SO₃ partly, the bulk of NO was oxidized to NO₂, and both were removed by resorbing finally.     

Preparation and structure characteristics of nano-Bi2O3 powders with mixed crystal structure

The nano-Bi2O3 powders were prepared by a chemical precipitation method with Bi(NO3)3, HNO3 and NaOH as reactants. The structural characteristics and morphology of nano-Bi2O3 powders were investigated by X-ray diffraction and transmission electron microscopy, respectively. The results show that under the optimum condition that 300g/L Bi(NO3)3 reacts at 90℃ for 2 h, the Bi203 powders with 60 nm on the average and 99.5% in purity are obtained. The prepared nano-Bi2O3 powders contain a mixed crystal structure of monoclinic and triclinic instead of traditional structure of monoclinic α-Bi2O3. And the mixed crystal structure is stable in air. The reason for the appearance of the mixed crystal structure may be that the ionic radius ratio of Bi^3 to O^2- changes easily during the formation of nano-Bi2O3 particles by a chemical precipitation method.     

First-principles calculation of dehydrogenating properties of MgH2-V systems

Based on experimental results in which VH_0.81/MgH₂ interface was found during the process of mechanically milling MgH₂+5at%V nanocomposite, a VH/MgH₂ interface is designed and constituted in this work. A first-principles plane-wave pseudopotential method based on Density Functional Theory (DFT) has been used to investigate the vanadium alloying effects on the dehydrogenating properties of magnesium hydride, i.e., MgH₂. A low absolute value of the negative heat of formation of VH/MgH₂ interface compared with that of MgH₂ indicates that vanadium hydrides befit to improve the dehydrogenating properties of MgH₂. Based on the analysis of the density of states (DOS) and the total valence electron density distribution of MgH₂ before and after V alloying, it was found that the improvement of the dehydrogenating properties of MgH₂ caused by V alloying originates from the increasing of the valence electrons at Fermi level (E _F) and the decreasing of the HOMO-LUMO gap (ΔE _H-L) after V alloying. The catalysis effect of V on dehydrogenating kinetics of MgH₂ may attribute to a stronger bonding between V and H atoms than that between Mg and H atoms, which leads to nucleation of the α-Mg at the VH/MgH₂ interface in the MgH₂-V systems easier than that in pure MgH₂ phase.     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi_0.45Co_0.10Mn_0.45O₂ was synthesized from Li₂CO₃ and a triple oxide of nickel, cobalt and manganese at 950 °C in air. The structures and characteristics of LiNi_0.45Co_0.10Mn_0.45O₂, LiCoO₂ and LiMn₂O₄ were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi_0.45Co_0.10Mn_0.45O₂ has a layered structure with hexagonal lattice. The commercial LiCoO₂ has sphere-like appearance and smooth surfaces, while the LiMn₂O₄ and LiNi_0.45Co_0.10Mn_0.45O₂ consist of cornered and uneven particles. LiNi_0.45Co_0.10Mn_0.45O₂ has a large discharge capacity of 140.9 mA · h/g in practical lithium ion battery, which is 33.4% and 2.8% above that of LiMn₂O₄ and LiCoO₂, respectively. LiCoO₂ and LiMn₂O₄ have higher discharge voltage and better rate-capability than LiNi_0.45Co_0.10Mn_0.45O₂. All the three cathodes have excellent cycling performance with capacity retention of above 89.3% at the 250th cycle. Batteries with LiMn₂O₄ or LiNi_0.45Co_0.10Mn_0.45O₂ cathodes show better safety performance under abusive conditions than those with LiCoO₂ cathodes. Foundation item: Project(50302016) supported by the National Natural Science Foundation of China; Project(2005037698) supported by the Postdoctoral Science Foundation of China     

First-principles investigation of the phase stability of MgAl2 compounds

First-principles have been calculated to investigate the phase stabilities of the intermetallic phase of MgAl2 compounds by electronic structures and the charge distribution maps.The first-principles e...