N-doped graphene quantum dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube composite photocatalysts for antibiotic photodegradation and H2 production

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

TiO2纳米管的制备及其光电性能研究

采用水热法成功地制备了厚度为1 nm,直径为15 nm的TiO_(2)纳米管。利用差热-热重分析、X射线衍射、透射电镜及紫外-可见漫反射光谱对产物的结构进行了表征,并通过TiO_(2)纳米管对甲基橙的降解效果对其光催化活性进行评价。结果表明:制备的TiO_(2)纳米管有锐钛矿和金红石两种晶型,反应时间对样品的组织结构和光催化活性有较大影响,金红石相比例随着反应时间的增长而减少。反应时间为12 h时,TiO_(2)纳米管具有更佳的晶型比例及形貌结构,光催化性能最好。通过对TiO_(2)纳米管的形成机理研究发现:TiO_(2)前驱体先在强碱的作用下形成片状结构的碱金属钛盐,然后,该片状结构在表面静电作用和弹性形变等多因素诱导下转变成更稳定的纳米管状结构。

One-Pot Green Synthesis of 1, 4-Dihydropyridine Derivatives Using Polyindole TiO2 Nanocatalyst by Solvent Free Method

This study used a Polyindole in combination with TiO2 nanocatalyst as an efficient heterogeneous catalyst to carry out a multi-component Hantzsch reaction involving different aromatic aldehydes with methyl acetoacetate, and aqueous ammonium to create 1,4-dihydropyridine derivatives under solvent free condition at ambient temperature. A broad range of aldehydes and methyl acetoacetates, ranging from heteroaromatic to polyaromatic one, with high level of functional group tolerance can be used to provide the desired products possessing relevant medicinal moiety in high yields. This technology has prospective advantages over current protocols, including the utilization of a cheap, stable, recyclable, and safe catalyst, quicker reaction times with higher yields and simple product isolation.

TiO2/Fe-ZSM-5光催化降解印染废水

印染废水非常难处理。随着氧化降解的大量发展,各种先进的氧化技术,包括光催化、臭氧分解、声催化光芬顿、光电芬顿技术等已经成为破坏顽固化合物的技术的一。迄今为止,已经深入研究了各种预期应用中的TiO2光催化性能的研究,即掺杂剂添加、合成技术改性和异质复合材料结构。在本研究中,TiO2/Fe-ZSM-5复合材料的光催化活性将成为光催化剂,并且将确定最佳操作参数。本实验在pH值为9,RhB浓度为5 ppm,光强度为538 w/m2,TiO2/Fe-ZSM-5添加量为0.5 g/L时,有最佳降解效率。

Two-dimensional ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes for enhanced photocatalytic water splitting hydrogen production

Two-dimensional (2D) ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method.Bare TiO2 nanotubes were fabricated via electrospinning.Then,2D MoS2 lamellae were grown on the surface of the nanotubes and Ti^3+/Ov ions were introduced by reduction.The photocatalytic performance of the 2D MoS2/Ti^3+-TiO2 nanotubes was^15 times better than that of TiO2.The HER enhancement of the MoS2/Ti^3+-TiO2 nanotubes can be attributed to the Pt-like behavior of 2D MoS2 and the presence of Ti^3+-ions,which facilitated the quick diffusion of the photogenerated electrons to water,reducing the H2 activation barrier.The presence of Ov ions in the nanotubes and their hollow structure increased their solar utilization.

BiVO4/TiO2(N2) Nanotubes Heterojunction Photoanode for Highly Efficient Photoelectrocatalytic Applications

We report the development of a novel visible response BiVO_4/TiO_2(N_2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO_2 nanotube shows a high carrier concentration rate, thus resulting in a high efficient charge transportation and low electron–hole recombination in the TiO_2–BiVO_4. Therefore, the BiVO_4/TiO_2(N_2) NTs photoanode enabled with a significantly enhanced photocurrent of 2.73 mA cm^(-2)(at 1 V vs. Ag/Ag Cl) and a degradation efficiency in the oxidation of dyes under visible light. Field emission scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometer, and UV–Vis absorption spectrum were conducted to characterize the photoanode and demonstrated the presence of both metal oxides as a junction composite.

Supporting IrO2 and IrRuOx nanoparticles on TiO2 and Nb-doped TiO2 nanotubes as electrocatalysts for the oxygen evolution reaction

IrO2 and IrRuOx(Ir:Ru 60:40 at%),supported by 50 wt%onto titania nanotubes(TNTs)and(3 at%Nb)Nb-doped titania nanotubes(Nb-TNTs),as electrocatalysts for the oxygen evolution reaction(OER),were synthesized and characterized by means of structural,surface analytical and electrochemical techniques.Nb doping of titania significantly increased the surface area of the support from 145(TNTs)to 260 m2g-1(Nb-TNTs),which was significantly higher than those of the Nb-doped titania supports previously reported in the literature.The surface analytical techniques showed good dispersion of the catalysts onto the supports.The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV)species,the suitable form to behave as a donor introducing free electrons to the conduction band of titania.The redox transitions of the cyclic voltammograms,in agreement with the XPS results,were found to be reversible.Despite the supported materials presented bigger crystallite sizes than the unsupported ones,the total number of active sites of the former was also higher due to their better catalyst dispersion.Considering the outer and the total charges of the cyclic voltammograms in the range 0.1–1.4 V,stability and electrode potentials at given current densities,the preferred catalyst was Ir O2 supported on the Nb-TNTs.The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping,thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER.The good dispersion of IrO2,high specific surface area of the Nb-doped supports,accessibility of the electroactive centers,increased stability due to Nb doping and electron donor properties of the Nb(IV)oxide species were considered the main reasons for its good performance.

Nitrogen-doped carbon encapsulated in mesoporous TiO2 nanotubes for fast capacitive sodium storage

Controllable synthesis of insertion-type anode materials with beneficial micro-and nanostructures is a promising approach for the synthesis of sodium-ion storage devices with high-reactivity and excellent electrochemical performance.In this study,we developed a sacrificial-templating route to synthesize TiO_(2)@N-doped carbon nanotubes(TiO_(2)@NC-NTs)with excellent electrochemical performance.The asprepared mesoporous TiO_(2)@NC-NTs with tiny nanocrystals of anatase TiO_(2) wrapped in N-doped carbon layers showed a well-defined tube structure with a large specific surface area of 198 m^(2) g^(-1) and a large pore size of~5 nm.The TiO_(2)@NC-NTs delivered high reversible capacities of 158 m A h g^(-1) at 2 C(1 C=335 m A g^(-1))for 2200 cycles and 146 m A h g^(-1) at 5 C for 4000 cycles,as well as an ultrahigh rate capability of up to 40 C with a capacity of 98 m A h g^(-1).Even at a high current density of 10 C,a capacity of 138 m A h g^(-1) could be delivered over 10,000 cycles.Thus,the synthesis of mesoporous TiO_(2)@NC-NTs was demonstrated to be an efficient approach for developing electrode materials with high sodium storage and long cycle life.

Photothermal Therapy Using TiO2 Nanotubes in Combination with Near-Infrared Laser

We report the in vitro cell test and in vivo animal test results of titanium oxide nanotubes (TiO2 NTs) as a potential therapeutic agent used for cancer thermotherapy in combination with near-infrared (NIR) laser. The in vitro cell test results show that both the cells exposed to NIR laser without TiO2 NTs treatment and the cells treated with TiO2 NTs but not with NIR irradiation had cell viabilities higher than 96%. Combination of these two techniques, however, shows cell viability less than 1%. The cell death rate strongly depended on the concentration of TiO2 NTs. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results show that tumor cells can be completely destroyed without nearly giving damage to surrounding healthy cells by an injection of an adequate amount of TiO2 NTs/NaCl suspension and a subsequent single continuous laser treatment at a moderately low laser illumina-tion intensity for the exposure time optimized for the tumor size. These results suggest that TiO2 NTs can be effectively utilized as a therapeutic agent for cancer thermotherapy due to their excellent photothermal property and high bio-compatibility.

Photocatalytic Oxidation of Low Molecular Weight Hydrocarbon Gases over Pt-TiO2 Nanotubes

Pt-TiO2 nanotubes with tube diameter of -120 nm and uniformly dispersed Pt particles（size of -2 nm） were successfully synthesized via a carbon nanotube（CNT） templating method followed by a photo-deposition processing of Pt nanoparticles. The as-obtained Pt-TiO2 NTs possess both enhanced visible light absorption and reduced recombination of photogenerated electrons and holes. These merits boost the Pt-TiO2 NTs an excellent photocatalytic material toward photooxidation of a variety of low molecular hydrocarbons under atmospheric environment.

Preparation and Characterization of TiO2 Nanotubes Decorated by CuO and CeO2 Particles

A novel catalyst,TiO2 nanotubes(TiO2 NTs)composite decorated by CuO and CeO2 particles,was prepared by a simple and cost-effective method.The TiO2 NTs were fabricated by the hydrothermal method,and CuO and CeO2 particles loaded onto TiO2 NTs(CuO/CeO2@TiO2 NTs)were prepared by the water bath heating method.The CuO/CeO2@TiO2 NTs were investigated and characterized by transmission electron microscope(TEM),energy dispersive spectrometer(EDS),photoluminescence(PL),X-ray diffractometer(XRD)and ultraviolet-visible light diffuse reflectance spectrum(UV-Vis DRS).Both the p-n heterojunction formed at the p-CuO and n-TiO2 interfaces and the highly induced electron transfer of CeO2 can greatly promote the separation of electrons-holes.Therefore,CuO/CeO2@TiO2 NTs show enhanced absorption and have potential applications in photocatalysis.

豆芽模板合成TiO2材料及其光催化还原Cr(Ⅵ)的性能研究

以廉价易得的豆芽为模板,通过将豆芽简单浸泡在钛前驱液中制备得到了保留豆芽形貌的多孔TiO2材料,通过XRD、N2吸附-脱附、SEM、TEM、XPS、UV-vis和荧光光谱进行表征,并对其紫外光下光催化还原Cr(Ⅵ)的性能进行探究。结果表明,在以甲酸为空穴牺牲剂的条件下,以豆芽茎为模板的TiO2(BSS-TiO2)效果最佳,光催化还原率为60 min达到100%,比无模板TiO2的光催化活性提高了22%,且该材料表现出较好的稳定性。

聚苯胺-TiO2复合膜对316L不锈钢耐蚀性能的影响

以苯胺单体和纳米TiO2胶体溶液为电解液,采用电化学聚合法在316L不锈钢表面合成了聚苯胺(PANI)膜和PANI-TiO2复合膜,并利用扫描电镜、X射线衍射等检测手段对PANI-TiO2复合膜的316L不锈钢表面进行了表征,用循环伏安法和动电位极化曲线研究不同pH值下苯胺聚合的效果及不同TiO2含量对316L不锈钢耐蚀性能的影响。结果表明,在pH为2.5的条件下,聚苯胺的聚合效果最好;相比于单一聚苯胺膜,PANI-TiO2复合膜对316L不锈钢具有更好的保护性能。当TiO2添加量为1.5 g时,制备的复合膜对提高316L不锈钢的耐蚀性效果最佳,其腐蚀电位为-0.55 V。

Experimental and computational study of visible light-induced photocatalytic ability of nitrogen ions-implanted TiO2 nanotubes

Nitrogen-doped TiO2 nanotubes(TNTs)were prepared by ion implantation and anodic oxidation.The prepared samples were applied in photocatalytic(PC)oxidation of methyl blue,rhodamine B,and bisphenol A under light irradiation.To explore the influence of doped ions on the band and electronic structure of TiO2,computer simulations were performed using the VASP code implementing spin-polarized density functional theory(DFT).Both substitutional and interstitial nitrogen atoms were considered.The experimental and computational results propose that the electronic structure of TiO2 was modified because of the emergence of impurity states in the band gap by introducing nitrogen into the lattice,leading to the absorption of visible light.The synergy effects of tubular structures and doped nitrogen ions were responsible for highly efficient and stable PC activities induced by visible and ultraviolet(UV)light.

Enhanced ionic conductivity in a novel composite electrolyte based on Gd-doped SnO_(2) nanotubes for ultra-long-life all-solid-state lithium metal batteries

All-solid-state electrolytes are exceedingly attractive because of the outstanding inherent safety and energy density compared to liquid electrolytes.Whereas,it is still formidable to simultaneously design solid electrolytes with favorable electrode/electrolyte interface compatibility and high ionic conductivity in a simple and scalable manner.Hence,the oxygen-vacancy-rich Gd-doped SnO_(2) nanotubes(GDS NTs)are innovatively prepared and applied to the electrolyte of all-solid-state lithium metal batteries for the first time.The addition of GDS NTs can validly construct long-range co ntinuous ion transport networks in the poly(ethylene oxide)(PEO)-based system and greatly improve the mechanical properties of the electrolyte.Compared to the PEO-based electrolyte,the composite electrolyte displays a higher lithium ion conductivity of 2.41×10^(-4) S cm^(-1) at 30℃,a higher lithium ion transference number up to 0.62 and a wider electrochemical window of 5 V at 50℃.In addition,the composite electrolyte manifests outstanding compatibility with high-voltage LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)cathode,LiFePO4 cathode and lithium metal anode.The assembled Li/Li symmetric battery exhibits stable Li plating/stripping cycling performance,which can cycle steadily for 1500 h at a capacity of 0.3 mA h cm^(-2).And Li/LiFePO4 battery still maintains a high capacity of 131.54 mA h g^(-1) at 0.5C after 800 cycles,which has a superior capacity retention rate of 93.2%.The obtained novel composite electrolyte has promising application prospects in the field of all-solid-state lithium metal cells.

In-situ incorporation of halloysite nanotubes with 2D zeolitic imidazolate framework-L based membrane for dye/salt separation

Layered assembled membranes of 2D leaf-like zeolitic imidazolate frameworks(ZIF-L)nanosheets have received great attention in the field of water treatment due to the porous structure and excellent antibacterial ability,but the dense accumulation on the membrane surface and the low permeate flux greatly hinder their application.Herein,we synthesized m HNTs(modified halloysite nanotubes)/ZIF-L nanocomposites on modified m HNTs by in situ growth method.Interestingly,due to the different size of m HNTs and ZIF-L,m HNTs were packed in ZIF-L nanosheets.The hollow m HNTs provided additional transport channels for water molecules,and the accumulation of the ZIF-L nanosheets was decreased after assembling m HNTs/ZIF-L nanocomposites into membrane by filtration.The prepared m HNTs/ZIF-L membrane presented high permeate flux(59.6 L·m^(-2)·h^(-1)),which is 2-4 times of the ZIF-L membranes(14.8 L·m^(-2)·h^(-1)).Moreover,m HNTs/ZIF-L membranes are intrinsically antimicrobial,which exhibit extremely high bacterial resistance.We provide a controllable strategy to improve 2D ZIF-L assembles,and develops novel membranes using 2D package structure as building units.

Binary molten salt in situ synthesis of sandwich-structure hybrids of hollowβ-Mo2C nanotubes and N-doped carbon nanosheets for hydrogen evolution reaction

Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.

金红石型纳米TiO2对镉胁迫下水稻光合特性及镉、钛富集的影响

本文采用种植箱试验,研究金红石型纳米二氧化钛(TiO2-NPs)对镉胁迫下水稻光合特性及镉、钛富集的影响。试验结果表明,金红石型TiO2-NPs单一处理下对水稻叶绿素含量影响较小,随着金红石型TiO2-NPs浓度升高,对水稻叶绿素影响增大;单一Cd处理,导致水稻叶绿素含量增加;高浓度、小粒径的Cd与金红石型TiO2-NPs共同作用毒性增强,对水稻叶绿素含量影响较大。金红石型TiO2-NPs单一处理、单一Cd处理和二者结合可使水稻蒸腾速率和气孔导度逐渐增加,而净光合速率和胞间CO2浓度则明显下降;蒸腾速率、胞间CO2浓度、气孔导度与对照组没有显著差异,但净光合速率在金红石型TiO2-NPs与Cd的作用下出现不同程度的变化。水稻中镉主要在根部富集,Cd与金红石型TiO2-NPs联合作用会降低Cd的迁移率。水稻中根部钛含量远大于叶部,Cd与金红石型TiO2-NPs联合处理可以增加Ti的迁移率。这些试验结果可为探寻金红石型TiO2-NPs与Cd对水稻的单一与联合效应提供一定帮助和参考。

Cu修饰TiO2纳米纤维及其光催化性能研究

TiO2是一类半导体技术光催化剂,在发展新能源技术领域、医疗卫生、净化室内空气质量方面具有潜在用途。但TiO2仍具光生载流子复合严重的问题而限制了其光催化性能。为解决上述问题,本论文采用Cu修饰TiO2纳米纤维,提高光催化CO2还原为CH4活性。首先通过高压静电纺丝制备TiO2纳米纤维,后将Cu修饰在纳米纤维TiO2催化剂上,系统表征所制备样品的物理化学性质,并探究其光催化还原CO2性能。结果显示,3%Cu/TiO2样品CO2还原为CH4效率为19.2μmolg-1h-1,是单纯TiO2的2.2倍。