过渡金属离子掺杂改性TiO2的光催化性能研究进展

对近年来利用过渡金属离子掺杂改性TiO     

Cu掺杂TiO2及其纳米管的制备、表征与光催化性能

通过溶胶-凝胶法和水热法制备了Cu掺杂TiO₂纳米粉末及其纳米管,并通过XRD、TEM、FE-SEM、EDS、UV-Vis/DRS等手段分析了样品的结构。发现以Cu掺杂TiO₂纳米粉末为水热反应原料制备的纳米管中不含Cu,对其原因进行了分析讨论并通过Zn掺杂TiO₂纳米粉末证实：以金属掺杂TiO₂纳米粉末为原料,通过水热法制备TiO₂纳米管中不含有相应金属离子,这是由于金属离子在强碱水热条件下形成金属配离子,使金属离子溶解于水中而不能形成金属掺杂TiO₂纳米管。对所得样品进行了光催化性能测试,发现：Cu掺杂TiO₂粉末的光催化产氢效率为0.75 μmol·(g·h)^-1,高于由其本身及P25通过水热法制备的TiO₂纳米管(分别为：0.42 μmol·(g·h)^-1,0.25 μmol·(g·h)^-1)的光催化产氢效率。     

氮掺杂纳米多孔TiO2∶EDTA-Na2辅助水热合成及光催化性能

利用螯合剂乙二胺四乙酸二钠(EDTA-Na₂)作为致孔剂,以三氯化钛(TiCl₃)为前驱体,利用水热法直接合成了氮掺杂的纳米多孔TiO₂。通过 SEM、XRD、IR、低温N2吸附-脱附、XPS、热重分析(TG)和紫外可见(UV)光谱对样品进行了表征与分析。结果表明所合成TiO₂以锐钛矿相形式存在,氮掺在TiO₂晶面之间,具有典型的介孔结构和较高的比表面积,通过改变EDTA-Na₂的浓度,比表面积可控制在95~216 m²·g^-1之间。这种纳米多孔TiO₂在光降解甲基橙的实验中表现出很好的光催化活性,且随着EDTA-Na₂的浓度增大而逐渐增加。     

胶体碳球制备新型Sn/Se共掺杂TiO2及其光催化性能

TiO₂的光催化性能改性是水污染治理和光催化领域研究的重点方向。为了增强TiO₂的光催化性能,以胶体碳球为模板,采用水热-煅烧法首次制备了TiO₂空心球、硒掺杂二氧化钛(Se-TiO₂)空心球和锡/硒共掺杂二氧化钛(Sn/Se-TiO₂)空心球。同时,对Sn/Se-TiO₂空心球的形貌、结构以及元素组成进行了表征,并以罗丹明B为模拟污染物,评价了样品的光催化性能。结果表明：TiO₂为单一的锐钛矿相,Sn和Se成功地掺杂进入了TiO₂晶格中;Sn/Se共掺杂形成了缺陷能级,降低了禁带宽度和电子-空穴对的复合几率,提高了可见光的响应范围。当Se掺杂2.0%(物质的量分数,下同),Sn掺杂0.5%时,样品光催化性能最好,去除率为76.92%。同等条件下空心球的光催化去除率：TiO₂22,说明Sn/Se共掺杂T...     

La和Cu掺杂对纳米TiO2光生电荷性质的影响及其与光催化活性的关系

采用溶胶-水热法制备了未掺杂的和分别掺杂1%(摩尔浓度)La的、Cu的及La和Cu共掺杂的纳米TiO₂, 并主要利用表面光电压谱(SPS)和光致发光光谱(PL)等技术考察了掺杂对纳米TiO₂表面光生电荷性质的影响, 也探讨了其性质与光催化活性的关系. 结果表明: La的掺杂能够抑制TiO₂相变, 同时其不仅促进TiO₂光生载流子分离, 而且丰富了束缚表面态. 但是Cu的掺杂却与La的作用相反. 这些解释了在光催化氧化降解罗丹明B过程中, La掺杂有利于TiO₂光催化活性的提高, 而Cu掺杂对光催化反应是不利的. 此外, La和Cu共掺杂并没有体现出协同效应.     

SiO2负载氮掺杂TiO2可见光响应光催化剂的制备及性能

以四氯化钛为钛源,尿素为氮源,采用液相水解-沉淀法制得SiO2负载N掺杂TiO2可见光响应TiO2-xNy/SiO2光催化剂(TSN)。以苯酚为模型物,考察了TSN在可见光区、紫外光区及太阳光下的光催化活性,以及催化剂的使用寿命、分离性能。采用XPS、FTIR、UV-Vis DRS、XRD、TEM和低温氮物理吸附等对催化剂的结构进行表征。结果表明,N以阴离子形式进入TiO2体相并置换晶格中的O,适量N掺杂的TSN在紫外光区、可见光区及太阳光下均表现出较高的活性。SiO2与TiO2界面间有Ti-O-Si键形成,结合牢固。N掺杂在TiO2表面生成Ti-O-N键,形成新的能级结构,使催化剂的吸收红移至450~500 nm,诱发TiO2可见光催化活性。SiO2负载可减小TiO2颗粒平均尺寸,增加催化剂比表面积;同时SiO2负载还可改善催化剂的分离性能,提高催化剂使用寿命。     

P掺杂量对纳米TiO2结构及其光催化甘油水溶液制氢性能的影响

以钛酸丁酯为前驱体,以NaH2PO4为掺杂离子给体,采用溶胶-凝胶法制备了系列P掺杂的TiO2光催化剂,运用N2吸附-脱附、透射电子显微镜、X射线衍射、傅里叶变换红外吸收光谱、激光拉曼光谱、紫外-可见光漫反射等技术对催化剂进行了表征.结果表明,适量掺杂的P可以进入TiO2骨架中,而掺杂量过高时,P将溶解于TiO2晶格间隙中;P掺杂后的TiO2均为具有介孔结构的锐钛矿晶型纳米颗粒,其晶粒变小,分散度明显提高.适量P掺杂增大样品的比表面积,并使得TiO2禁带内引入杂质能级,降低了禁带能量,增加了光生电子和空穴的分离性能,提高了TiO2的吸光性能.光催化甘油水溶液制氢反应结果表明,P掺杂的TiO2表现出远高于纯TiO2的光催化活性;5%P掺杂样品在紫外光和模拟太阳光辐射下,其最高产氢速率可分别达1838和209μmol/(g.h).这与掺P后晶粒变小、比表面积增大、禁带能量降低以及光生电子和空穴的分离性能增加有关.     

掺杂TiO2的光催化性能研究进展

本文综述了掺杂TiO2在可见光范围的响应及其光催化性能的研究状况,讨论了掺杂金属离子的种类、浓度、光催化剂的粒径以及其它因素对TiO2光催化活性的影响。列出了掺杂TiO2的制务方法,并对今后的研究作了展望。     

甲酰胺对介孔N-TiO2微结构及光催化性能的影响

以钛酸四丁酯为前躯体,甲酰胺为氮源,采用溶胶凝胶法制备了具有可见光活性氮掺杂二氧化钛(N-TiO2)光催化剂.通过XPS、XRD、低温N2吸附.脱附和UV-Vis等表征,考察甲酰胺加入量对样品微结构和可见光活性的影响.当甲酰胺与钛酸四丁酯的物质的量的比为2、4、8、13时,制备的样品晶粒粒径在8～12 nm范围内,孔径在9～16咖范围内,孔隙率在54%～63%之间.甲酰胺与钛酸四丁酯的物质的量的比为13时,所制备样品具有较强的可见光吸收性能,其最大吸收边扩展到570 nm左右,禁带宽度减小至2.18 eV,比纯二氧化钛禁带宽度3.20 eV降低了1.02 eV.结果表明:随着甲酰胺加入量的增加,样品的晶粒粒径、孔径、孔隙率明显变大,禁带宽度减小.对甲基橙的室内自然光降解实验证明.氮掺杂二氧化钛具有良好的光催化活性,当甲酰胺与钛酸四丁酯的物质的量的比为13时,催化剂对甲基橙的降解率最高,为98.3%.     

炭黑吸附法制备掺杂镨TiO2纳米粉体及其光催化性能

以硝酸镨为掺杂的前驱物,钛酸异丙酯为TiO2的前驱物,通过炭黑吸附高温水热法制得掺杂镨的量为0.07%的纳米Pr3+/TiO2粉体。分别采用热重/差热分析(TG-DTA)、X射线衍射(XRD)、扫描电镜(SEM)、紫外可见分析(UV-VIS)和比表面积吸附(BET)对不同焙烧温度下所得粉体的物相、颗粒度、分散性及光吸收性能进行表征和分析。实验结果表明:炭黑的吸附阻止了粉体在干燥和煅烧阶段的团聚和烧结,制得的Pr3+/TiO2纳米粉体团聚较少,呈现良好的分散性,颗粒均匀,经500℃焙烧,得到纳米粉体平均颗粒直径为18 nm,比表面积为78.08 g.m-2。光催化降解实验表明,炭黑吸附后TiO2的光催化活性在一定时间内比没有炭黑的提高了将近2倍,在紫外灯照射下Pr3+/TiO2能在60 min内对亚甲基蓝的降解率达到93%。     

金属组分对TiO2光催化氧化NO-2反应的影响

亚硝酸根离子;金属组分对TiO2光催化氧化NO-2反应的影响     

半导体复合CdS/TiO2催化剂改性及冷冻-光催化组合方法应用的初步研究

采用溶胶-凝胶法制备多孔氧化钛,并耦合CdS,制备多孔耦合CdS/TiO₂催化剂.煅烧温度为700℃,CdS掺杂比例为3%时,催化剂性能较优.以太阳光为光源,考查了溴氨酸初始浓度对其降解效果的影响,并采用冷冻-光催化组合方法对较高浓度的溴氨酸废水的处理进行了初步研究.浓度为500 mg/L的溴氨酸模拟废水(其中氯化钠质量浓度为500 mg/L)经冷冻后,当成冰率为70%时,体系中冰层的Na⁺含量、总有机碳(TOC)和吸光度分别由209.88 mg/L,208.90 mg/L和8.120降至19.06 mg/L,24.80 mg/L和0.638.使用多孔耦合催化剂对该冰层融水光降解,光照6 h,褪色率和TOC去除率分别达到100%和87.04%.     

Fe3+-H掺杂TiO2光催化剂的制备、表征与催化性能

Fe3+-H掺杂TiO2光催化剂的制备、表征与催化性能;二氧化钛;掺杂;光催化;铁离子;等离子体     

Preparation, characterization and photocatalytic activity of visible light driven chlorine-doped TiO2

A novel chlorine-doped titanium dioxide catalyst with visible light response was prepared by hydrolysis of tetrabutyl titanate in hydrochloric acid. The catalyst samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Results showed that the doped element of Cl lowered the temperatures of phase transformation of TiO₂ from amorphous to anatase and from anatase to rutile. The absorption edge of chlorine-doped TiO₂ calcined at 300°C shifted to visible light region. X-ray photoelectron spectroscopy results proved that chlorine existed in the TiO₂ crystal lattice as anion. The photocatalytic degradation of phenol showed that under visible light (λ > 400 nm) irradiation, the chlorine-doped TiO₂ calcined at 300°C displayed the best performance, the degradation ratio of phenol was 42.5% after 120 min. Translated from Chinese Journal of Catalysis, 2006, 27(10): 890–894 [译自: 催化学报]     

过渡金属掺杂二氧化钛光催化性能的研究

采用浸渍法制备了过渡金属掺杂的光催化剂MOx/TiO2(M=Cr、Mn、Fe、Co、Ni、Cu).以乙酸的光催化氧化降解反应为探针,研究了催化剂的光催化性能.研究结果表明,经过渡金属掺杂改性的二氧化钛,光催化性能都有所提高.掺杂量有一个最佳值,在最佳掺杂量时,催化剂光催化性能的提高程度与对应金属氧化物的生成焓有很好的一致性,还发现光催化性能与过渡金属离子稳定氧化态的电子亲和势与离子半径的比值间呈现火山型关系曲线.     

Probing the Electronic Structure and Photoactivation Process of Nitrogen‐Doped TiO2 Using DRS,PL, and EPR

The electronic structure and photoactivation process in N‐doped TiO₂ is investigated. Diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and electron paramagnetic resonance (EPR) are employed to monitor the change of optical absorption ability and the formation of N species and defects in the heat‐ and photoinduced N‐doped TiO₂ catalyst. Under thermal treatment below 573 K in vacuum, no nitrogen dopant is removed from the doped samples but oxygen vacancies and Ti³⁺ states are formed to enhance the optical absorption in the visible‐light region, especially at wavelengths above 500 nm with increasing temperature. In the photoactivation processes of N‐doped TiO₂, the DRS absorption and PL emission in the visible spectral region of 450–700 nm increase with prolonged irradiation time. The EPR results reveal that paramagnetic nitrogen species (N_s^.), oxygen vacancies with one electron (V_o^.), and Ti³⁺ ions are produced with light irradiation and the intensity of N_s^. species is dependent on the excitation light wavelength and power. The combined characterization results confirm that the energy level of doped N species is localized above the valence band of TiO₂ corresponding to the main absorption band at 410 nm of N‐doped TiO₂, but oxygen vacancies and Ti³⁺ states as defects contribute to the visible‐light absorption above 500 nm in the overall absorption of the doped samples. Thus, a detailed picture of the electronic structure of N‐doped TiO₂ is proposed and discussed. On the other hand, the transfer of charge carriers between nitrogen species and defects is reversible on the catalyst surface. The presence of oxygen‐vacancy‐related defects leads to quenching of paramagnetic N_s^. species but they stabilize the active nitrogen species N_s^?.     

Nitrogen Doping and Carbon Coating Affects Substrate Selectivity of TiO2 Photocatalytic Organic Pollutant Degradation

A series of carbon-coated, nitrogen-doped titanium dioxide photocatalysts was produced and characterized. N-doped TiO₂ powder samples were prepared using a sol-gel method and subsequently used for making doped-TiO₂ thin films on glass substrates. Carbon layers were coated on the films by a thermal decomposition method using catechol. Diffuse reflectance spectra and Mott-Schottky analyses of the samples proved that nitrogen doping and carbon coating can slightly lower the band gap of TiO₂, broaden its absorption to visible light and enhance its n-type character. According to photocatalytic tests against model contaminants, carbon-coated nitrogen-doped TiO₂ films have better performance than simple TiO₂ on the degradation of Rhodamine B dye molecules, but are poorly effective for degrading 4-chlorophenol molecules. Several possible explanations are proposed for this result, supported by scavenging experiments. This reveals the importance of a broad substrate scope when assessing new photocatalytic materials for water treatment, something which is often overlooked in many literature studies.     

Electronic and Structural Properties of Highly Aluminum Ion Doped TiO2 Nanoparticles: A Combined Experimental and Theoretical Study

This study presents the experimental and theoretical study of highly internally Al‐doped TiO₂ nanoparticles. Two synthesis methods were used and detailed characterization was performed. There were differences in the doping and the crystallinity, but the nanoparticles synthesized with the different methods share common features. Anatase to rutile transformation occurred at higher temperatures with Al doping. X‐ray photoelectron spectroscopy showed the generation of oxygen vacancies, which is an interesting feature in photocatalysis. In turn, the band‐gap energy and the valence band did not change appreciably. Periodic density functional calculations were performed to model the experimentally doped structures, the formation of the oxygen vacancies, and the band gap. Calculation of the density of states confirmed the experimental band‐gap energies. The theoretical results confirmed the presence of Ti⁴⁺ and Al³⁺. The charge density study and electron localization function analysis indicated that the inclusion of Al in the anatase structure resulted in a strengthening of the Ti?O bonds around the vacancy.     

An Unexplored O2‐Involved Pathway for the Decarboxylation of Saturated Carboxylic Acids by TiO2 Photocatalysis: An Isotopic Probe Study

The aerobic decarboxylation of saturated carboxylic acids (from C₂ to C₅) in water by TiO₂ photocatalysis was systematically investigated in this work. It was found that the split of C¹? C² bond of the acids to release CO₂ proceeds sequentially (that is, a C₅ acid sequentially forms C₄ products, then C₃ and so forth). As a model reaction, the decarboxylation of propionic acid to produce acetic acid was tracked by using isotopic‐labeled H₂¹⁸O. As much as ≈42 % of oxygen atoms of the produced acetic acids were from dioxygen (¹⁶O₂). Through diffuse reflectance FTIR measurements (DRIFTS), we confirmed that an intermediate pyruvic acid was generated prior to the cut‐off of the initial carboxyl group; this intermediate was evidenced by the appearance of an absorption peak at 1772 cm^?1 (attributed to C?O stretch of α‐keto group of pyruvic acid) and the shift of this peak to 1726 cm^?1 when H₂¹⁶O was replaced by H₂¹⁸O. Consequently, pyruvic acid was chosen as another model molecule to observe how its decarboxylation occurs in H₂¹⁶O under an atmosphere of ¹⁸O₂. With the α‐keto oxygen of pyruvic acid preserved in the carboxyl group of acetic acid, ≈24 % new oxygen atoms of the produced acetic acid were from molecular oxygen at near 100 % conversion of pyruvic acid. The other ≈76 % oxygen atoms were provided by H₂O through hole/OH radical oxidation. In the presence of conduction band electrons, O₂ can independently accomplish such C¹? C² bond cleavage of pyruvic acid to generate acetic acid with ≈100 % selectivity, as confirmed by an electrochemical experiment carried out in the dark. More importantly, the ratio of O₂ participation in decarboxylation increased along with the increase of pyruvic acid conversion, indicating the differences between non‐substituted acids and α‐keto acids. This also suggests that the O₂‐dependent decarboxylation competes with hole/OH‐radical‐promoted decarboxylation and depends on TiO₂ surface defects at which Ti_4c sites are available for the simultaneous coordination of substrates and O₂.