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.

Bi_(2)WO_(6)-N-TiO_(2)纳米管电极的制备及性能分析

采用水热法与低温等离子体法制备了Bi_(2)WO_(6)-N-TiO_(2)纳米管电极,对其进行SEM、EDS、XRD、UV-VIS-DRS、CV和I-t等手段表征,并应用于环丙沙星抗生素废水的降解。结果表明,Bi_(2)WO_(6)纳米片成功的负载到TiO_(2)纳米管电极表面,Bi_(2)WO_(6)和N的共同改性显著增强了TiO_(2)对可见光的吸收。电化学分析结果表明经过改性后的TiO_(2)纳米管电极具有优异的光电转换性能,光电流密度约是改性前的5~9倍。Bi_(2)WO_(6)-N-TiO_(2)纳米管电极对环丙沙星污染物的降解过程遵循一级动力学反应方程,其中0.8 mmol Bi_(2)WO_(6)-N-TiO_(2)纳米管电极的降解速率最高,可以达到0.00683 min^(-1)。

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.

Pt-N-TiO_(2)纳米管电极的制备及其表征

采用光化学沉积法与等离子体法制备Pt-N-TiO_(2)纳米管电极,SEM、EDS以及XRD等表征手段表明TiO_(2)纳米管管径约为90 nm,Pt纳米颗粒均匀负载至纳米管管口且未改变TiO_(2)纳米管结构。UV-Vis-DRS表明Pt-N-TiO_(2)纳米管光吸收性能在可见光区相比掺Pt前提高明显。CV、EIS电化学性能分析表明Pt-N-TiO_(2)纳米管表面电荷转移加快,具有更好的导电性能和氧化性能。通过降解目标染料甲基紫分析Pt-N-TiO_(2)纳米管的光电催化性能,在初始浓度10 mg/L,pH=3,外加偏压25 V,Pt负载浓度为1 g/L,甲基紫60 min降解率93.64%,降解过程符合一级动力学反应方程。

颗粒状N-TiO_(2)的制备及其光催化活性

采用溶剂热法制备氮掺杂二氧化钛(N-TiO_(2))光催化剂,以亚甲基蓝(MB)为降解目标,探讨了不同的合成条件对产物的影响,以及催化剂质量、染料初始质量浓度和pH等因素对N-TiO_(2)催化性能的影响,初步研究了其催化和吸附的动力学过程。结果表明:在尿素与钛源质量比为1∶1,合成温度和时间为180℃和18 h条件下,合成的纳米N-TiO_(2)是由粒径为30~60 nm的纳米颗粒团聚形成的大颗粒,禁带宽度为3.1 eV;在可见光照射下,当N-TiO_(2)的质量为0.075 g,染料的初始质量浓度为25 mg/L,以及pH=5时,其催化效果良好;此外,其催化和吸附MB的过程分别符合一级动力学过程和准二级动力学模型。

Three-dimensional Porous Networks of Ultra-long Electrospun SnO_2 Nanotubes with High Photocatalytic Performance

Recent progress in nanoscience and nanotechnology creates new opportunities in the design of novel SnO2 nanomaterials for photocatalysis and photoelectrochemical. Herein, we firstly highlight a facile method to prepare threedimensional porous networks of ultra-long SnO2 nanotubes through the single capillary electrospinning technique.Compared with the traditional SnO2 nanofibers, the as-obtained three-dimensional porous networks show enhancement of photocurrent and photocatalytic activity, which could be ascribed to its improved light-harvesting efficiency and high separation efficiency of photogenerated electron–hole pairs. Besides, the synthesis route delivered three-dimensional sheets on the basis of interwoven nanofibrous networks, which can be readily recycled for the desirable circular application of a potent photocatalyst system.

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.

TEM Study on the Formation Process of TiO_2 Nanotubes

The process, that the polycrystalline TiO2 powders were converted into TiO2 nanotubes, was observed with transmission electron microscope. The results obtained indicated that in concentrated NaOH aqueous solution, anisotropic swelling appears on the polycrystalline TiO2 granula at first, and then the nanotubes are formed.

Photo-degradation of Acid-red 3B dye catalyzed by TiO_2 nanotubes

TiO2 nanotube precursor was synthesized by the hydrothermal reaction of TiO2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron microscopic （TEM） observation revealed that the nanotube could be obtained by either a direct rinse with acid solution or rinse with distilled water followed by acid solution. The results of X-ray diffraction （XRD） and inductively coupled plasma （ICP） analysis indicated that the nanotube material was composed of H2Ti2O5·H2O. In addition, the photocatalytic activities of the resulting catalysts were found to be strongly dependent on the post-treatment. The results of the photocatalytic reaction showed that the degradation of Acid-red 3B dye fitted pseudo-zero-order kinetics and TiO2 nanotube prepared under direct rinse with acid solution exhibited a higher catalytic efficiency compared to other catalysts.

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.

CuAl-LDHs/CNTs优势组装及电催化CO_(2)还原制甲醇的研究

双碳背景下,电催化CO_(2)制甲醇等化合物有重要研究价值。为了提高CO_(2)的转化率和甲醇的选择性,本文借助兼具酸碱性的铜铝类水滑石(CuAl-LDHs)和具有优异导电性的碳纳米管材料(CNTs),协调构筑了LDHs/CNTs杂化物,实现了两种材料的优势互补,使其制甲醇性能和导电性能双向提高。研究结果表明,相较于LDHs,杂化物中二者良好的分散性和丰富的弱碱位点更有利于CO_(2)分子在其表面大量吸附并快速扩散,同时具有高迁移率的晶格氧和高还原电位的一价铜物种在催化剂表面形成了氧化还原循环,显著降低了传质阻力和电子转移难度,使得CuAl-LDHs/5%CNTs在-0.6 V(针对可逆氢电极)下对甲醇拥有较高的选择性和电流密度,最高可达80.7%和-6.5 mA/cm 2,为开发在低电位高电流密度下具有高CO_(2)转化率的LDHs基电催化剂提供了重要参考。

Fabrication of Fe_2O_3@polypyrrole Nanotubes and the Catalytic Properties Under the Ultrasound

Fe2O3@polypyrrole nanotubes （Fe2O3@PPy nanotubes） have been successfully prepared by in-situ polymerization of the pyrrole on the surface of Fe2O3 nanotubes （Fe2O3-NTs）, via using L-Lysine as modified surfactant. Hollow PPy nanotubes were also produced by dissolution of the Fe2O3 core from the core/shell composite nanotubes with 1 mol,L-1 HC1. Scanning electron microscopy（SEM）, transmission electron microscope （TEM）, selective-area electron diffraction （SAED）, X-ray powder diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared spectroscopy（FT-IR） confirmed the formation of Fe2O3-NTs and Fe2O3@PPy core/shell nanotubes. Its catalytic properties were investigated under the ultrasound. The results of UV-vis spectroscopy （UV） demonstrated Rhodamine B （RhB） can be efficiently degraded by Fe2O3 @PPy nanotubes.

Preparation of Polyaniline/TiO_2 Composite Nanotubes for Photodegradation of AZO Dyes

Polyaniline （PANI） composite nanotubes （90-130 nm in diameter） containing titanium dioxide （TiO2） nanoparticles （about 10 nm in diameter） were synthesized through a self-assembly process in the presence of a-naphthalenesulfonic acid （a-NSA） as the dopant. It was found that PANI-TiO2 composites and PANI nanotubes both behaved with significant photocatalytic activities towards AZO dyes, during 2 h photocatalytic processes under natural light, the degradation ratio was 94.2% and 97.2% respectively （methyl orange and orange II）. The morphology of such products was characterized by SEM. The specific surface area of such composite nanotubes was 14.7 m2/g compared to normal polyaniline which was 0.27 m2/g. IR and X-ray diffraction characterizations showed that the chemical chain of the composite nanotubes was identical to that of the doped PANI. It may provide a new way for photodegradation of organic contaminants by using conjugated polymer with dimensional structure.

Nickel nanoparticles supported on nitrogen-doped carbon nanotubes are a highly active,selective and stable CO_(2) methanation catalyst

CO_(2) methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route.Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were synthesized by impregnation,calcination and reduction and characterized by elemental analysis,X-ray powder diffraction,H_(2) temperature-programmed reduction,CO pulse chemisorption and transmission electron microscopy.The Ni/NCNT catalysts were highly active in CO_(2) methanation at atmospheric pressure,reaching over 50% CO_(2) conversion and over 95% CH_(4) selectivity at 340℃ and a GHSV of50,000 mL g^(-1) h^(-1) under kinetically controlled conditions.The small Ni particle sizes below 10 nm despite the high Ni loading is ascribed to the efficient anchoring on the N-doped CNTs.The optimum loading of 30 wt%-40 wt% Ni was found to result in the highest Ni surface area,the highest degree of conversion and the highest selectivity to methane.A constant TOF of 0.3 s^(-1) was obtained indicating similar catalytic properties of the Ni nanoparticles in the range from 10 wt%to 50 wt% Ni loading.Long-term experiments showed that the Ni/NCNT catalyst with 30 wt% Ni was highly stable for 100 h time on stream.

Two-Dimensional Co_(2)(OH)1,4-Benzenedicarboxylate-Halloysite Nanotube Nanocomposite-Epoxy Coating with High Corrosion Resistance

Introducing inorganic nanomaterials into a polymer matrix greatly improves the anticorrosion performance of epoxy coatings(EP);however,poor compatibility between the materials can limit the improvement in properties.In this work,based on the high interface compatibility of two-dimensional(2D)Co_(2)(OH)_(2)BDC(BDC=1,4-benzenedicarboxylate)in the epoxy coating that we reported in previous work,we fabricated a 2D Co_(2)(OH)_(2)BDC-halloysite nanotube(HNT)nanocomposite have a structure consisting of alternating of nanosheets and nanotube by in situ synthesis.The nanocomposite was characterized by Fourier transform infrared spectroscopy,X-ray diffraction,and scanning electron microscopy.The mechanical and anticorrosion performance of the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was evaluated by mechanical tests and electrochemical impedance spectroscopy spectra.Compared with a conventional unreinforced epoxy coating,the 2D Co_(2)(OH)_(2)BDC-HNT/EP coating had higher mechanical strength and toughness,and the low-frequency impedance modulus of 2D Co_(2)(OH)_(2)BDC-HNT/EP coating was increased by three orders of magnitude,demonstrating the high corrosion resistance of our reinforced coating.

Preparation by High-gravity Technology of a Cu/N-TiO_(2) Nanophotocatalyst for Photodegradation of Phenol Wastewater

TiO_(2) is a promising photocatalyst,but its practical use is restricted by its low catalytic efficiency caused by the large particle size and uneven size distribution,which arise from the limited contact area of the liquid-liquid interface during synthesis.Impinging stream-rotating packed bed(IS-RPB)reactors,which are used for process intensification,overcome the mixing limitation of traditional stirred-tank reactors and provide a micromixing environment at the molecular scale for the two liquid phases,which can reduce the particle size and distribution range.Cu/N-TiO_(2) nanoparticles were prepared in an IS-RPB reactor by the one-step precipitation method using urea as the nitrogen source,titanyl sulfate as the titanium source,copper chloride as the copper source,and ammonium hydroxide as the precipitant.The particle size of the photocatalyst was about 11.40 nm with a narrow size distribution measured by scanning electron microscopy and transmission electron microscopy.X-ray photoelectron spectroscopy showed that N replaced some O and was uniformly dispersed in the TiO_(2) lattice as interstitial and substitutional N.Cu replaced some Ti and was present as Cu^(2+).The synergistic effects of these two elements formed a new impurity energy level and reduced the band gap energy of the TiO_(2) nanoparticles.The specific surface area of the Cu/N-TiO_(2) nanoparticles was 152.97 m^(2)/g.The effects of the main factors on the degradation rate were studied,and the removal efficiency reached 100%under the optimal operating conditions after 2 h ultraviolet irradiation.The electron paramagnetic resonance measurements showed that the superoxide radical played a main role in the degradation process,whereas the photogenerated holes and hydroxyl radicals had weak effects.

原位生长的CNTs@MoS_(2)杂化物增强水性膨胀型防火涂料的耐火和隔热性能

目的设计并研制一种耐火和隔热性能突出的水性膨胀型防火涂料。方法以碳纳米管(CNTs)、四水合钼酸铵、十六烷基溴化铵(CTAB)、硫脲为原料,通过简单的一步水热法原位生长出一种新型的CNTs@MoS_(2)杂化物,并采用FT-IR、XRD、拉曼光谱、SEM等手段对复合杂化物进行表征。再将CNTs@MoS_(2)杂化物作为增效剂分散在水性膨胀型防火涂料(CNTs@MoS_(2)/WES)中,通过大板实验和涂层、炭焦层表面分析评价了涂层的耐火和隔热性能。结果与WES(膨胀倍率为3.90)、CNTs/WES涂层(膨胀倍率为6.04)、MoS_(2)/WES涂层(膨胀倍率为4.59)相比,CNTs@MoS_(2)/WES涂层具有最高的膨胀倍率(8.88)。CNTs@MoS_(2)/WES涂层所涂覆的钢板在燃烧40min后背面温度最低(133.3℃),这充分表明该涂层具有优异的隔热性能。结论制备的CNTs@MoS_(2)杂化物表现出稳定的网络交织结构,有效提高了它在涂料中的分散性能。此外,CNTs@MoS_(2)/WES涂层优异的耐火和隔热性能主要归因于:1)CNTs@MoS_(2)/WES涂层及其炭焦层具有更致密和完整的表面,阻隔了热量的传递;2)CNTs的添加增强了炭焦层的致密性,抑制了膨胀过程中产生的气体泄漏,提升了涂层膨胀倍率;3)MoS_(2)提高了膨胀层强度且促进了炭焦层的形成,减少了裂纹和孔隙的产生。

Fabrication and Characterization of Lanthanide-TiO2 Nanotube Composites

Titanium dioxide (TiO2) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Titanium dioxide nanotubes (TNTs) and in-situ Nd-doped and/or Gd-doped TNTs were characterized with transmission and scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Morphologies indicated a network of aggregated nanotubes. The phase and composition analyses revealed that the lanthanide TNTs had anatase phases with Nd and/or Gd nanoparticles in the TNT lattice. The nanoparticles were uniformly deposited on the surface because of hydroxyl groups on the TNT surfaces, resulting in a very high loading density. The outer diameter and the length of the TNTs increased with doping. The mechanisms for the formation of multiwall TNTs are discussed.