Pt-TiO2纳米管电极的制备及电催化性能

采用电化学阳极氧化-阴极还原法制备Pt-TiO2纳米管电极.扫描电镜(SEM)结果显示TiO2纳米管平均管径100nm,管长470nm,管壁厚20nm,且其比表面积大,同时纳米Pt微粒分散在TiO2纳米管上,且粒径细小,Pt微粒充分裸露,使得Pt-TiO2纳米管电极活性点多,电催化性能高.对甲醇的电催化性能测试表明:同纯Pt电极和Pt-TiO2电极(Pt微粒固定在TiO2致密膜上)相比,Pt-TiO2纳米管电极对甲醇具有更高的电催化活性,其氧化峰电流密度是在纯Pt片电极上的20倍以上.     

TiO2-B/anatase core-shell heterojunction nanowires for photocatalysis

Fast separation and spatial control of electrons and holes after photogeneration is important in photocatalysis. Ideally, after photogeneration, electrons and holes must be segregated to different parts of the photocatalyst to take part in separate oxidation and reduction reactions. One way to achieve this is by building junctions into the catalyst with built-in chemical potential differences that tend to separate the electron and the hole into two different regions of the catalyst. In this work, we sought to accomplish this by controllably forming junctions between different phases of TiO(2). A synthesis method has been developed to prepare TiO(2)-B core and anatase shell core-shell nanowires. We control the anatase phase surface coverage on the TiO(2)-B core and show that the maximum photocatalytic activity is obtained when the solution containing the reactants can contact both the anatase and TiO(2)-B phases. The photocatalytic activity drops both with bare TiO(2)-B nanowires and with completely anatase covered TiO(2)-B nanowires. In contrast, nanowires partially covered with anatase phase gives the highest photocatalytic activity. The improved photocatalytic activity is attributed to the effective electron-hole separation at the junction between the anatase and TiO(2)-B phases.     

Photocatalytic degradation of rhodamine B by anchored TiO2 nanowires

Rutile TiO2 nanowires anchored on silica were fabricated by annealing TiO2 nanoparticles dispersed on silicon or quartz substrate by means of a polystyrene nanosphere monolayer template at 1000 degrees C for 1 h without any catalyst. The diameter and length of the nanowires were 30-80 nm and 1-3 microm, respectively. The growth direction of the nanowires is [112]. The photocatalytic activities of TiO2 nanoparticles and anchored nanowires were evaluated. TiO2 nanowires had higher photocatalytic activity for rhodamine B than TiO2 nanoparticles.     

Rose Bengal-Cu-TiO2的制备及可见光制氢活性研究

用光还原方法制备了负载Cu的光催化剂Cu-TiO2，并通过染料Rose bengal敏化，制备了具有可见光活性的Rose bengal-Cu-TiO2光催化剂，通过可见光下光解水制氢考察了催化剂的活性，并利用XRD、UV-Vis等手段对样品进行了表征。实验表明：载Cu增强了TiO2对可见光的吸收，Cu负载量对催化剂活性有一定的影响，Cu的最佳负载量为5％（质量分数）。Cu的负载也增加了TiO2对染料的吸附强度和吸附量，从而提高了TiO2对可见光的吸收和光催化活性。但载Cu的TiO2催化剂的活性和传统的载贵金属Pt的TiO2催化剂相比，其光催化活性较低，有待进一步提高．     

Deactivation mechanism of PtOx/TiO(2) photocatalyst towards the oxidation of NO in gas phase

This study has been undertaken to investigate the roles of PtO and PtO(2) deposits in photocatalytic oxidation of NO over Pt-modified TiO(2) catalysts. These photocatalysts were prepared by neutralization method and characterized by XRD, BET, XPS, TEM and FTIR. It was found that Pt dopant existed as PtO and PtO(2) particles in as-prepared photocatalysts. And these Pt dopants would change their oxidation states during the photocatalytic oxidation reaction. An in situ XPS study indicated that a portion of PtO(2) on the surface of Pt/TiO(2) was reduced to PtO under UV irradiation. The migration of electrons to PtO(2) particles could separate the electrons and holes, resulting in the improvement of photocatalytic activity. And the depletion of PtO(2) by electrons could lead to the deactivation of Pt/TiO(2) catalyst. Moreover, PtO particles could be corroded to form Pt(2+) ions by HNO(3), which was one of the products of photocatalytic oxidation of NO. NO would adsorb on Pt(2+) related sites to form Pt(n+)-NO nitrosyls, retarding photocatalytic oxidation of NO to NO(2).     

Oxidation of triclosan by ferrate: reaction kinetics, products identification and toxicity evaluation

The Crystal Violet (CV) dye represented one of the major triphenylmethane dyes used in textile-processing and some other industrial processes. Various metals doped titanium dioxide (TiO(2)) photocatalysts have been studied intensively for the photodegradation of dye in wastewater treatment. In order to understand the mechanistic detail of the metal dosage on the activities enhancement of the TiO(2) based photocatalyst, this study investigated the CV photodegradation reactions under UV light irradiation using a Pt modified TiO(2) photocatalyst. The results showed that Pt-TiO(2) with 5.8% (W/W) Pt dosage yielded optimum photocatalytic activity. Also the effect of pH value on the CV degradation was well assessed for their product distributions. The degradation products and intermediates were separated and characterized by HPLC-ESI-MS and GC-MS techniques. The results indicated that both the N-de-methylation reaction and the oxidative cleavage reaction of conjugated chromophore structure occurred, but with significantly different intermediates distribution implying that Pt doped TiO(2) facilitate different degradation pathways compared to the P25-TiO(2) system.     

Hierarchical top-porous/bottom-tubular TiO2 nanostructures decorated with Pd nanoparticles for efficient Photoelectrocatalytic decomposition of synergistic pollutants

In this paper, top-porous and bottom-tubular TiO(2) nanotubes (TiO(2) NTs) loaded with palladium nanoparticles (Pd/TiO(2) NTs) were fabricated as an electrode for an enhanced photoelectrocatalytic (PEC) activity toward organic dye decomposition. TiO(2) NTs with a unique hierarchical top-porous and bottom-tubular structure were prepared by a facile two-step anodization method and Pd nanoparticles were decorated onto the TiO(2) NTs via a photoreduction process. The PEC activity of Pd/TiO(2) NTs was investigated by decomposition of methylene blue (MB) and Rhodamine B (RhB). Because of formation Schottky junctions between TiO(2) and Pd, which significantly promoted the electron transfer and reduced the recombination of photogenerated electrons and holes, the Pd/TiO(2) NT electrode showed significantly higher PEC activities than TiO(2) NTs. Interestingly, an obvious synergy between two dyes was observed and corresponding mechanism based on facilitated transfer of electrons and holes as a result of a suitable energy level alignment was suggested. The findings of this work provide a fundamental insight not only into the fabrication but also utility of Schottky junctions for enhanced environmental remediation processes.     

New TiO2/MgAl-LDH nanocomposites for the photocatalytic degradation of dyes

In this study we report the synthesis of a series of composite nanostructures comprising LDH and TiO2 phases. The materials characterization showed that the LDH crystallites are encapsulated inside the TiO2 matrix after the anatase seeds are deposited on MgxAl-LDHs. The structure in which LDH phase is embedded into anatase matrix is unique bringing important advantages to the photocatalytic performances of the nanocomposites. The photocatalytic activity of the prepared nanocomposites was tested on the degradation of the methylene blue (MB) in aqueous solution. The photocatalytic activities of the nanocomposites were compared with commercial TiO2 nanoparticles Degussa P25. The nanocomposites exhibited superior photocatalytic activity in basic environment because the negatively charged surface of TiO2 nanoparticles at high pH attracts the positively charged methylene blue species.     

Enhanced visible light photocatalytic activity of novel Pt/C-doped TiO2/PtCl4 three-component nanojunction system for degradation of toluene in air

C-doped TiO(2) nanoparticles prepared by partial oxidation of TiC were modified with Pt species by impregnation-calcination method in order to enhance the visible light photocatalytic activity. The physicochemical properties of as-prepared samples were characterized by various techniques in detail. The results indicated that a novel Pt/C-doped TiO(2)/PtCl(4) three-component nanojunction system was formed, where C-doped TiO(2) and PtCl(4) behaved as two visible light responsive components, and Pt metal as electron-transfer system. The three-component nanojunctioned photocatalyst system exhibited six times higher visible light activity than that of the pristine C-doped TiO(2) in degradation of toluene in air. The dramatically enhanced activity can be attributed to the increased utilization of visible light, the enhanced charge carrier separation and transfer process. Further more, the band structure and photocatalysis mechanism over the three-component nanojunction system was proposed and discussed. This work may provide new insights into the design of novel multi-component photocatalyst system with efficient visible light activity.     

铂修饰的TiO2柱撑膨润土复合光催化剂的制备及光催化活性研究

钛酸四异丙酯在醋酸溶液中水解生成的多核钛离子经离子交换反应插入到膨润土层间，制得钛柱撑膨润土(TiO2-PILC)，再通过光沉积法合成了一系列不同铂量修饰的钛柱撑膨润土(Pt-TiO2-PILCs)；用XRD、BET和TEM对制得的复合催化剂进行了性能表征；以五氯酚钠为目标污染物，考察了它们的催化活性．结果表明：柱撑膨润土中TiO2主要以锐钛型存在，含铂的Pt-TiO2-PILCs的催化活性明显高于TiO2-PILC．此外该复合催化剂还具有回收容易、重复使用性好等特点．     

负载Pt的TiO2的抑菌性能研究

目的通过贵金属负载来提高Ti O2光催化抑菌性能。方法利用光沉积法制备Pt/Ti O2,通过XRD,UV-Vis漫反射吸收光谱和TEM对样品进行表征,Ti O2为锐钛矿和金红石型混晶,经过Pt担载之后Ti O2对光的吸收增强。利用溶液振荡法,以大肠杆菌为目标物,研究在光照和非光照条件下Ti O2和Pt/Ti O2的抑菌性能。结果在光照条件下,Ti O2的抑菌率为45%,Pt担载质量分数为10%的Ti O2的抑菌率为60%,Pt担载之后Ti O2的抑菌率提高了15%。结论 Ti O2光催化剂具有抑制大肠杆菌生长的性能,负载Pt后,由于Pt的化学势较低,光生电子被富集到Pt的表面,减小了光生电子和光生空穴复合的几率,更多的光生空穴被游离出来,因此Pt/Ti O2的抑菌性能得到了提高。     

Fabrication of TiO2/Ti electrode by laser-assisted anodic oxidation and its application on photoelectrocatalytic degradation of methylene blue

A TiO2/Ti mesh electrode by laser calcination was prepared in this article. The resulting TiO2 film was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS), and it illuminated that the prepared electrode mainly consisted of anatase TiO2 nanoparticles on its surface and exhibited a superior photocatalytic activity. The photodegradation of methylene blue (MB) using the proposed electrode under different experimental conditions was investigated in terms of both UV absorbance at 664 nm and chemical oxygen demand (COD) removal. The electrical bias applied in photoelectrocatalytic (PEC) oxidation was also studied. The experimental results showed that under the optimal potential of +0.50 V (versus SCE), UV absorbance and COD removal during the photodegradation of MB by the proposed TiO2/Ti mesh electrode were 97.3% and 87.0%, respectively. Through the comparison between photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation, it was found that PEC oxidation was a convenient and effective way to mineralize the organic matters and that laser-treated photoelectrode exceeded the oven-treated one.     

Structural and optical properties of glancing angle deposited TiO2 nanowires array

TiO2 nanowires (NWs) have been synthesized by glancing angle deposition technique using e-beam evaporator. The average length 490 nm and diameter 80 nm of NWs were examined by field emission-scanning electron microscopy. Transmission electron microscopy emphasized that the NWs were widely dispersed at the top. X-ray diffraction has been carried out on the TiO2 thin film (TF) and NW array. A small blue shift of 0.03 eV was observed in Photoluminescence (PL) main band emission for TiO2 NW as compared to TiO2 TF. The high temperature annealing at 980 degrees C partially removed the oxygen vacancy from the sample, which was investigated by PL and optical absorption measurements.     

Construction of hierarchical nanostructured TiO2/Bi2MoO6 heterojunction for improved visible light photocatalysis

In this study, Bi2MoO6 hollow microspheres were modified by depositing TiO2 nanoparticles through a simple hydrothermal method. The prepared TiO2/Bi2MoO6 photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic performance of the heterostructured catalysts was evaluated by degradation of methylene blue (MB) under visible-light irradiation (lambda>420 nm). The photocatalysts based on nanostructured Bi2MoO6 and TiO2 exhibit much higher photocatalytic activity than the single-phase Bi2MoO6 or TiO2 and the mechanical mixture of Bi2MoO6 and TiO2 for degradation of MB under the same conditions. The results reported in this study provide insight into constructing other heterostructured photocatalysts.     

Bulk production of porous TiO2 nanowires by unique solvo-plasma oxidation approach for combating biotic and abiotic water contaminants

Pure, porous titania nanowires (TiO₂-pNW) are produced in bulk amount (~?250 kg/day, reaction time scale?<?1 min) using a unique solvo-plasma oxidation method utilizing microwave plasma with the potential of easy scale up. The prepared nanowire is found to be efficient towards both biotic disinfection and destruction of various abiotic contaminants in wastewaters. In terms of organic contaminants, the TiO₂-pNW is tested for destruction of Rhodamine B (RhB) dye, tetracycline (TC) antibiotic, and diclofenac (DFC) and caffeine (CAF) drugs. In the case of biotic contaminants, the disinfection of E. coli bacteria is demonstrated. In all of the studies, the photocatalytic performance of anatase TiO₂-pNW is compared to that of commercially available P25 nanoparticles (TiO₂-P25), both in the presence and absence of ozone. The excellent photoactivity exhibited by TiO₂-pNW is a result of low recombination rate of electron–hole pair owing to the spatial separation of electrons and holes within the photoexcited nanowires. Moreover, the scavenger experiments and experiments involving ozone reveal that electron transfer and/or presence of dissolved oxygen are the major limiting factors for both porous titania nanowires and P25 spherical powder under UV exposure with photocatalytic activity towards pollutant degradation.

     

流化床化学气相沉积法制备CNT/Fe-Ni/TiO2及其光催化性能研究

以Fe-Ni/TiO2为催化剂,采用流化床化学气相沉积法(FBCVD)在TiO2表面原位生长碳纳米管(CNT),得到CNT/Fe-Ni/TiO2复合光催化剂.通过SEM、XRD、UV-Vis等方法表征其结构和性能,以亚甲基蓝溶液降解为模型考察其光催化性能.结果表明:Fe-Ni/TiO2催化剂在FBCVD过程中,镍主要起到了CNT生长催化活性位的作用;在生长CNT后的复合光催化剂中,比例较低的Fe3+主要作为电子俘获剂,抑制TiO2光生电子空穴的复合;Ni和CNT共同起到将电子迅速地从TiO2中导出,从而降低光生电子空穴复合几率的作用.三者的协同作用显著改善了TiO2的光催化性能.其中Fe和Ni掺杂量分别为0.25mol%和4.75mol%样品的光催化活性较高,生长CNT后得到的复合光催化剂对亚甲基蓝的降解效率较纯TiO2提高约70%.     

钛酸钠纳米线制备TiO_2纳米线的反应条件

结合离子交换-高温烧结法,由钛酸钠纳米线制备了TiO_2纳米线。通过XRD、Uv-vis漫反射和SEM等测试手段,探讨离子交换时间和高温烧结温度对制备TiO_2纳米线的影响,并以甲基橙为目标污染物测试其光催化性能。结果表明:离子交换时间越长越有利于钛酸纳米线的形成,离子交换48h时钛酸钠纳米线基本转换成为钛酸纳米线;过低的烧结温度不利于TiO_2纳米线的形成,烧结温度650℃时钛酸纳米线基本分解成为TiO_2纳米线;钛酸钠纳米线几乎没有光催化性能,而TiO_2纳米线具有很强的光催化性能。     

In‐Situ Confined Growth of Monodisperse Pt Nanoparticle@Graphene Nanobox Composites as Electrocatalytic Nanoreactors

Monodisperse Pt nanoparticles (NPs) studded in a three‐dimensional (3D) graphene nanobox are successfully synthesized through a simple in‐situ confined growth route for the first time. The nano‐zeolite A was used as a 3D substrate for in‐situ growth of tri‐layered graphenes on the crystal‐surfaces, meanwhile, the inner micropores of which can also be utilized for the confined growth of Pt nanoparticles. The graphene sheets are curved on the edges to form a 3D hollow box morphology, where the monodisperse Pt nanoparticles are homogeneously studded on the inner surfaces. Moreover, the Pt content can be regulated from ～8 to 50 wt%, and the particle size can be tuned from 2–5 nm by varying the pristine Pt‐ion loading amount and CVD temperature. The Pt NP@graphene nanoboxes possess not only large pore volumes to effectively accommodate large amounts of oxygen, but also supply excellent electrical conductivity for the fast transfer of electrons (～3.96 e^‐), resulting in a high efficiency (175 mA/mg Pt) and long‐term stability (above 1000 cycles) for the oxygen reduction reaction.     

Shape transformation and relaxation dynamics of photoexcited TiO2/Ag nanocomposites

The laser-induced sintering of TiO2 nanoparticles into larger nanospheres is accelerated by adsorbed silver particles. For the same weight fraction of silver, silver nanoparticles of 5 nm in diameter modify TiO2 nanoparticles more effectively than those of 1.5 nm do, suggesting that the photocatalysis of TiO2 nanoparticles as well as their stability is highly dependent on the sizes, the shapes, and the distribution of adsorbed metal nanoparticles. The photoexcited electrons of TiO2 nanoparticles are quenched at trap sites and surface states by transfer to the conduction band of silver, implying that the presence of adsorbed silver nanoparticles enhances the photocatalytic effect of TiO2.     

Preparation, characterization, and photocatalytic activity of Gd3+ doped TiO2 nanoparticles

TiO2 and Gd3+ doped TiO2 nanoparticles were prepared by sol-gel method and the materials were characterized by XRD, TEM, SEM-EDX, BET, FT-IR, UV-Vis absorption, and Raman spectral analysis. The photocatalytic activity of nano TiO2 and Gd/TiO2 nanoparticles was evaluated using a model pollutant propoxur, a carbamate pesticide, in a batch type UV photoreactor. The results revealed higher photocatalytic activity for Gd/TiO2 nanoparticles than both TiO2 nanoparticles and commercial TiO2 (Degussa P-25). The enhanced photocatalytic activity of Gd/TiO2 relative to TiO2 is attributed to its increased band gap energy as evidenced from the blue shift to shorter wavelength observed in the UV-Vis abso4ption spectra. The recombination rate of photogenerated electron-hole pair decreased due to increase in the band gap, which enhanced the charge transfer efficiency of Gd/TiO2 nanoparticles. Gd3+ with its half filled 7 f subshell facilitated rapid electron transfer at solid-liquid interface by shallowly trapping the electrons. Among the various dopant level of gadolinium, 0.3 wt% Gd/TiO2 nanoparticles showed higher activity than others due to its higher surface area.