酸催化水解法制备可见光响应N掺杂纳米TiO2催化剂

 以TiCl4为钛源,采用酸催化水解法合成了TiO2前驱体,在NH3/N2气氛中经程序升温处理制得不同N掺杂量的TiO2可见光响应催化剂. 以苯酚为模型物,考察了催化剂在可见光及紫外光区的催化活性. 采用X射线衍射、紫外-可见漫反射光谱、傅里叶变换红外光谱、扫描电镜和低温氮物理吸附对光催化剂的晶相结构、光谱特征和表面结构进行了表征. 结果表明,掺杂N后锐钛矿TiO2的可见光催化活性显著提高,在500 ℃焙烧5 h制得的催化剂在可见光区及紫外光区均表现出最高的光催化活性. N掺杂对TiO2的晶粒大小、比表面积和晶相结构影响不大. 适量N掺杂可在TiO2表面形成Ti-O-N键,形成了新的能级结构,使催化剂的吸收带边红移至490～550 nm; 同时该结构也可有效提高TiO2的紫外光催化活性.     

四丁基氢氧化铵改性TiO_2的可见光催化活性

采用溶胶-凝胶法和四丁基氢氧化铵(TBAH)表面改性的方法制备出改性TiO2光催化剂(TBAH-TiO2).利用X射线衍射谱(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)和表面光电压谱(SPS)等表征了催化剂的晶体结构、晶粒粒径和能带结构,并研究了其光催化活性.研究结果表明,TBAH-TiO2催化剂的表面主要存在NOx(x=1,2,3)物种,该物种能级(价带上0.20eV)产生了可见光响应,有效地促进了光生电子和光生空穴的分离,使催化剂的可见和紫外光催化活性显著提高,TBAH-TiO2催化剂降解对氯苯酚的可见光和紫外光催化活性分别是TiO2的2.6倍和1.7倍.     

三维有序结构In掺杂TiO_2薄膜的可见光催化活性

采用自组装生长聚苯乙烯胶体模板和溶胶-凝胶法,制备出三维(3D)有序结构In掺杂TiO2(IO-TiO2-In)薄膜可见光催化剂.光催化实验证明,IO-TiO2-In薄膜降解甲醛的可见光活性是TiO2和三维有序结构TiO2(IOTiO2)薄膜的5倍.利用X射线电子衍射(XRD)谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见(UV-Vis)漫反射吸收光谱确定了催化剂的晶相结构、表面微结构和能带结构.结果表明,IO-TiO2-In薄膜具有锐钛矿型三维有序结构,与TiO2相比,增加了比表面积,提高光的利用率;掺入的In离子在薄膜表面形成In2O3和O-In-Clx(x=1,2)物种,既增强可见光的吸收,又有效地促进了光生载流子的分离,提高了光生载流子在固/气界面参加光催化反应的利用率,使催化剂的可见光催化活性显著提高.     

S掺杂S-TiO_2/SiO_2可见光响应光催化剂的制备及性能

以四氯化钛为钛源,硫脲为硫源,采用液相水解-沉淀法制备了S掺杂的TiO2/SiO2(S-TiO2/SiO2)催化剂,并以苯酚为模型物,考察了催化剂在可见光区、紫外光区和太阳光下的光催化活性,以及催化剂的使用寿命和分离性能.采用X射线光电子能谱、傅里叶变换红外光谱、紫外-可见漫反射光谱、X射线衍射、透射电镜及N2吸附-脱附等技术对催化剂进行了表征.结果表明,S以+6价形式进入TiO2体相并置换晶格中的Ti4+,适量S掺杂的S-TiO2/SiO2在紫外光区、可见光区和太阳光下均表现出较高的光催化活性.SiO2与TiO2界面间有Ti-O-Si键形成,结合牢固.S掺杂在TiO2表面生成Ti-O-S键,形成新的能级结构,使光催化剂在450～550nm产生吸收,诱发TiO2可见光催化活性;同时提高了TiO2表面羟基数量.SiO2的加入可减小TiO2颗粒的平均尺寸,增大催化剂的比表面积,改善催化剂的分离性能,提高催化剂的使用寿命.     

SiO2负载的TiO2光催化剂可见光催化降解染料污染物

 采用酸催化溶胶-凝胶法制备了SiO2负载的TiO2光催化剂,考察了制备条件对负载型TiO2光催化剂的晶相、结构、比表面积和可见光催化活性的影响. 结果表明,采用SiO2为载体时,TiO2以纳米颗粒的形态分散在载体表面,负载型TiO2/SiO2催化剂的比表面积大、等电点低而且热稳定性能良好. 偶氮染料酸性橙7的可见光催化降解实验结果表明,染料污染物在催化剂表面的吸附是影响催化剂可见光催化活性的重要因素. 与试剂TiO2样品相比,负载型TiO2/SiO2光催化剂具有更好的光催化活性和沉降性能.     

N、F共掺杂TiO2可见光响应光催化剂的酸催化水解法制备及表征

采用酸催化水解法由TiCl4、NH4F混合液合成N、F共掺杂可见光响应TiO2光催化剂(TONF).以苯酚为模型物,考察了催化剂在可见光区、紫外光区的催化活性.采用X射线光电子能谱(XPS)、紫外.可见漫反射光谱(DRS)、X射线衍射(XRD)、打描电子显微镜(SEM)及低温氮物理吸附对光催化剂的晶相结构、光谱特征和表面结构等进行表征.结果表明,适量的N、F共掺杂TONF催化剂表现出较高的可见光催化活性.N、F共掺杂可显著提高TiO2分散性能,促进锐钛矿相的形成,抑制其向金红石相转变,提高相转变温度.N掺杂可提高TiO2在可见光区的吸收;F掺杂可使TiO2能隙变窄.     

N、F共掺杂TiO2可见光响应光催化剂的酸催化水解法制备及表征

采用酸催化水解法由TiCl4、NH4F混合液合成N、F共掺杂可见光响应TiO2光催化剂(TONF). 以苯酚为模型物, 考察了催化剂在可见光区、紫外光区的催化活性. 采用X射线光电子能谱(XPS)、紫外-可见漫反射光谱(DRS)、X射线衍射(XRD)、扫描电子显微镜(SEM)及低温氮物理吸附对光催化剂的晶相结构、光谱特征和表面结构等进行表征. 结果表明, 适量的N、F共掺杂TONF催化剂表现出较高的可见光催化活性. N、F共掺杂可显著提高TiO2分散性能, 促进锐钛矿相的形成, 抑制其向金红石相转变, 提高相转变温度. N掺杂可提高TiO2在可见光区的吸收; F掺杂可使TiO2能隙变窄.     

N、F共掺杂可见光响应介孔TiO2光催化剂:纤维素模板剂合成及活性

以纤维素为模板剂,TiCl4为钛源,采用液相水解-沉淀法制备了浅黄色的N、F共掺杂可见光响应介孔TiO2催化剂(TiONF)。以苯酚为模型物,考察了TiONF在紫外光区、可见光区及太阳光下催化活性;采用X射线光电子能谱(XPS)、傅里叶变换红外(FTIR)、紫外-可见漫反射光谱(UV-Vis DRS)、X射线衍射(XRD)、热重/量热扫描(TG/DSC)、透射电镜(TEM)及低温N2物理吸附-脱附等技术对TiONF催化剂的结构进行了表征。结果表明,以纤维素为模板剂合成适量N、F共掺杂的TiONF催化剂在紫外光区、可见光区及太阳光下均表现出较高的活性,且高于无模板剂合成的TiONF催化剂的活性。N、F共掺杂提高了TiO2表面羟基数量和锐钛矿相TiO2向金红石相转变的温度;N掺杂形成新的能级结构,诱发TiO2可见光催化活性;F掺杂促进TiO2粒子表面氧空穴产生,致使TiO2粒子表面酸度和Ti3+增加。另外,纤维素的加入可减小TiONF颗粒平均尺寸,改善催化剂分散性,提高催化剂比表面积。     

S掺杂宽光域响应Ti1-xSyO2光催化剂的制备及表征

以TiCl4和硫脲为主要原料, 采用酸催化水解法制得浅黄色S掺杂Ti1-xSyO2光催化剂. 以苯酚为模型物, 考察了Ti1-xSyO2在可见光区、紫外光区及太阳光下的催化活性. 采用XPS、DRS、XRD、FT-IR、SEM、低温氮物理吸附对光催化剂进行表征. 结果表明, 掺杂S以S6+形式置换TiO2晶格中的Ti4+, 适量S 掺杂的Ti1-xSyO2在可见光区、紫外光区及太阳光下均表现出较高的光催化活性.掺杂S 在TiO2表面形成新的能级结构, 使催化剂吸收红移至450-550 nm, 诱发可见光催化活性;紫外光照射下, 新形成的能级结构与体相TiO2形成复合半导体结构, 捕获光生空穴, 提高光生电子鄄空穴分离效率.同时, S掺杂可以改善TiO2的分散性, 增加其比表面积SBET并提高相转变温度.     

Si掺杂TiO2催化剂的结构与可见光催化活性研究

采用溶胶-凝胶法制备出Si⁴⁺离子掺杂的TiO₂可见光催化剂 (TiO₂-xSi),该催化剂的可见光催化活性高于纯TiO₂和N掺杂的TiO₂(TiO₂-N).利用XRD、XPS、FT-IR和UV-Vis DRS等表征技术,研究了TiO₂-xSi催化剂的晶体结构、能带结构和表面性质.研究发现:掺入Si⁴⁺离子在TiO₂粒子表面主要形成Ti-O-Si结构,并在导带下0.2-0.6 eV区域形成表面态能级,该表面态能级的存在是催化剂产生可见光响应、实现可见光催化的根本原因.另外,讨论了Si⁴⁺离子的掺杂对金红石相和晶粒的生长抑制作用,以及催化剂的比表面积和表面羟基物种增加对可见光催化活性的影响.     

Zr离子掺杂TiO2可见光催化剂光催化活性的研究

本文采用溶胶-凝胶法制备了Zr离子掺杂TiO₂光催化剂。光催化降解对氯苯酚实验表明,Zr离子掺杂浓度为10%时活性最高,其紫外光、可见光催化活性分别是纯TiO₂的1.5倍和4倍。利用XRD、Raman、XPS、UV-Vis DRS、PL等技术对样品进行了表征,结果表明：Zr离子以取代式掺杂方式进入TiO₂晶格,在TiO₂导带下方形成掺杂能级,增强了可见光响应,促进了光生载流子的分离,此外Zr离子掺杂在催化剂表面引入大量表面缺陷,增加了表面羟基物种,从而使得Zr离子掺杂TiO₂光催化剂的紫外、可见光催化活性显著提高。     

Bi2O3 /TiO2复合纳米颗粒的可见光光催化性能

采用溶胶与水热相结合的方法合成了具有可见光光催化活性的复合纳米颗粒Bi2O3/TiO2,并对其进行了X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射谱、红外光谱、低温N2吸附脱附及电子顺磁共振分析。结果表明,复合少量的氧化铋可显著抑制TiO2由锐钛矿到金红石的相转移过程,并将光吸收范围扩展到可见光区。可见光照射下(λ>420 nm),利用电子顺磁共振技术检测到明显的羟基自由基(.OH)信号。铋的最佳掺杂量为Bi/Ti质量比2.0%,适量铋的掺入能显著改善锐钛矿TiO2的结晶度,抑制光生电子-空穴对的复合,提高光催化量子效率。通过可见光照射下,4-氯酚的降解实验测试Bi2O3/TiO2复合纳米颗粒的可见光光催化活性。同时,利用气-质联用仪对4-氯酚降解过程的中间产物进行了测定,并提出可见光照射下的Bi2O3光敏化机理。     

Great enhancement of photocatalytic activity of nitrogen-doped titania by coupling with tungsten oxide

The TiO2-N-x%WO3 composite photocatalysts were prepared by introducing WO3 into nitrogen-doped TiO2. The composite catalysts present much higher photocatalytic activity than TiO2 and nitrogen-doped TiO2 under both ultraviolet and visible light irradiation. Diffuse reflectance UV-vis spectra, XPS analysis, and IR spectra show that the coordinated nitrogen species (or N-metal-O linkages) may contribute to the visible light photocatalytic activity. WO3 coupling increases the active nitrogen species and thus enhances the visible light activity of the composite photocatalysts. The superior activity of TiO2-N-x%WO3 composite photocatalysts upon UV light irradiation can be rationalized in terms of efficient charge separation and high adsorption affinity of WO3.     

Visible-light-induced photocatalytic degradation of 4-chlorophenol and phenolic compounds in aqueous suspension of pure titania: demonstrating the existence of a surface-complex-mediated path

The visible-light-induced degradation reaction of 4-chlorophenol (4-CP) was investigated in aqueous suspension of pure TiO2. Contrary to common expectations, 4-CP could be degraded under visible illumination (lambda > 420 nm), generating chlorides and CO2 concomitantly. The observed visible reactivity was not due to the presence of trace UV light since the visible-light-induced reactions exhibited behaviors distinguished from those of UV-induced reactions. Dichloroacetate could not be degraded under visible light, whereas it degraded with a much faster rate than 4-CP under UV irradiation. The addition of tert-butyl alcohol, a common OH radical scavenger, did not affect the visible reactivity of 4-CP, which indicates that OH radicals are not involved. Other phenolic compounds such as phenol and 2,4-dichlorophenol were similarly degraded under visible light. The surface complexation between phenolic compounds and TiO2 appears to be responsible for the visible light reactivity. Diffuse reflectance UV-vis spectra showed that 4-CP adsorbed on TiO2 powder induced visible light absorption. The visible light reactivity among several TiO2 samples was apparently correlated with the surface area of TiO2. The visible-light-induced photocurrents on a TiO2 electrode could be obtained only in the presence of 4-CP. It is proposed that a direct electron transfer from surface-complexed phenol to the conduction band of TiO2 upon absorbing visible light (through ligand-to-metal charge transfer) initiates the oxidative degradation of phenolic compounds. When the surface complex formation was hindered by surface fluorination, surface platinization, and high pH, the visible-light-induced degradation of 4-CP was inhibited. The evidence of visible-light-induced reactions and the experimental conditions affecting the visible reactivity were discussed in detail.     

多壁碳纳米管负载TiO_2复合器件可见光光催化降解RhB

采用溶胶-凝胶法制备了多壁碳纳米管(MWCNTs)负载的ITO/MWCNTs-TiO2/ITO复合器件,利用SEM、XPS、UV-Vis光谱等技术对复合样品进行形貌和结构表征,以液相罗丹明B(RhB)的可见光光催化降解为探针反应,评价MWCNTs-TiO2复合薄膜的催化活性.XPS结果表明MWCNTs与TiO2之间没有形成Ti-C键.I-V特性表明负载了MWCNTs的ITO/MWCNTs-TiO2/ITO复合器件的光电流增强.与空白TiO2薄膜相比,MWCNTs-TiO2复合薄膜的可见光光催化降解RhB的速率提高了3.2倍.MWCNTs并没有掺杂到TiO2晶格中,而是起到了类似光敏剂的作用,可在可见光激发下将导带电子转移到TiO导带上,经一系列反应降解RhB有机物.     

Active oxygen species (1O2, O2*-) generation in the system of TiO2 colloid sensitized by hypocrellin B

TiO2 semiconductor colloids have been successfully employed in environmental clean-up, antibacterial and bactericidal action under ultraviolet light due to its strong redox ability and high yield of active oxygen species (1O2, O2*-), *OOH) generation. Hypocrellin B, isolated from Hypocrella bambusae (B.et.Br) Sacc, a natural pigment with strong and broad absorption over the visible light region, was used in our work in an attempt to extend the photoresponse of TiO2 to visible light and maintain the high generation of active oxygen under visible light illumination. The formation of the HB-TiO2 chelate was characterized by UV-Vis and surface enhanced raman spectroscopy (SERS) and it was found that the chelate still had high efficiency of active oxygen generation. The possible generation mechanism was explored by Electron Paramagnetic Resonance (EPR) and time-resolved transient spectra techniques, showing that singlet oxygen (1O2) and superoxide radical anion (O2*-)) were produced via energy transfer and electron transfer, respectively. The application of HB-TiO2 chelate in environment protection and bacteria sterilization was implied.     

Photocatalytic degradation of methyl orange over metalloporphyrins supported on TiO2 Degussa P25

The photocatalytic activity of meso-tetraphenylporphyrins with different metal centers (Fe, Co, Mn and Cu) adsorbed on TiO(2) (Degussa P25) surface has been investigated by carrying out the photodegradation of methyl orange (MO) under visible and ultraviolet light irradiation. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance UV (DRS-UV-vis) and infrared spectra. Copper porphyrin-sensitized TiO(2) photocatalyst (CuP-TiO(2)) showed excellent activity for the photodegradation of MO whether under visible or ultraviolet light irradiation. Natural Bond Orbital (NBO) charges analysis showed that methyl orange ion is adsorbed easier by CuP-TiO(2) catalyst due to the increase of induced interactions.     

Ce及N共掺杂改性TiO_2光催化性能及Ce组分的作用

以钛酸正丁酯、硝酸亚铈及氨水为前驱体运用溶胶-凝胶法对TiO2进行Ce及N单一和共掺杂改性,以甲基橙光催化降解为探针考察掺杂组分对催化剂的紫外、可见光活性影响,观察到了Ce及N的单一掺杂及共掺杂催化剂紫外、可见光活性的明显提升。运用X射线衍射(XRD)、低温氮气吸附(BET)、紫外-可见漫反射吸收光谱(DRS)、程序升温氧脱附(TPD)和程序升温氧化(TPO)等表征手段从催化剂的晶体结构及形貌、比表面积、紫外及可见光响应特性、表面吸附氧量及吸附氧循环性能等方面尝试理解掺杂组分的光活性影响机制。实验结果表明掺杂改性催化剂中适量Ce组分的作用在于通过抑制催化剂的晶粒长大、团聚和锐钛结构向金红石结构的相转变,提高催化剂的光相应强度和拓展光响应范围,增加催化剂表面吸附氧容量和促进催化剂的表面氧循环,有效捕获光生载流子,衍生各类高活性自由基物种和增大催化剂比表面积等方面增进催化剂的光催化性能。     

Preparation and photocatalytic behavior of MoS2 and WS2 nanocluster sensitized TiO2

A new approach has been developed for the fabrication of visible light photocatalysts. Nanoclusters of MoS2 and WS2 are coupled to TiO2 by an in situ photoreduction deposition method taking advantage of the reducing power of the photogenerated electrons from TiO2 particles. The photocatalytic degradation of methylene blue and 4-chlorophenol in aqueous suspension has been employed to evaluate the visible light photocatalytic activity of the powders. The blue shift in the absorption onset confirms the size quantization of MS2 nanoclusters, which act as effective and stable sensitizers, making it possible to utilize visible light in photocatalysis. Quantum size effects alter the energy levels of the conduction and valence band edges in the coupled semiconductor systems, which favors the interparticle electron transfer. In addition, the coupled systems are believed to act in a cooperative manner by increasing the degree of charge carrier separation, which effectively reduces recombination.     

C/Nd/TiO2催化剂的制备及光催化性能研究

利用溶胶-凝胶法以钛酸四丁酯为钛源、硝酸钕为钕源、葡萄糖为碳源,制备了C和Nd单掺杂及共掺杂TiO_2催化剂。通过XRD、XPS、漫反射、SEM和物理吸附对所制备的催化剂进行表征与评价。结果表明,C和Nd共掺杂TiO_2的晶型仍为锐钛矿型,表面光滑,晶粒大小分散均匀,孔径分布在20~34 nm之间;与其他三种催化剂相比,共掺杂催化剂比表面积较大;通过掺杂C和Nd元素,形成新能带E_(C2p)和E_(Nd3+4f),降低了电子跃迁能,有利于光催化活性增强。C和Nd共掺杂TiO_2对可见光的吸收能力有明显提高,对甲基橙染料降解效果较佳,其脱色率为61.24%。