Branched core-shell a-TiO2@N-TiO2 nanospheres with gradient-doped N for highly efficient photocatalytic applications

A branched core-shell nanosphere composed of an anatase TiO₂ (a-TiO₂) core and a TiO₂ nanobranch shell with gradient-doped N (a-TiO₂@N-TiO₂) is synthesized by a simple in situ doping method, in which mixed crystal anatase-rutile TiO₂ (ar-TiO₂) nanosphere is first prepared by oxidizing Ti using H₂O₂, and then is etched by NH₃·H₂O to form (NH₄)₂TiO₃ nanobranches, which is converted into a-TiO₂@N-TiO₂ following an ambient annealing process. The diameter of a-TiO₂ core is ～500 nm, and the thickness of N-TiO₂ branched shell is ～100 nm with gradually increased N concentration from the bottom to the edge. Ultra-thin amorphous coating layers on the branches are also observed. The morphology of the composites could be further tuned by the amount of NH₃·H₂O, and its effect on the photocatalytic performance is also investigated. The optimized a-TiO₂@N-TiO₂ shows an outstanding hydrogen evolution rate of 308.1 μmol g^?1 h^?1 under air mass (AM) 1.5 illumination, and also exhibits highly active in photocatalytic degradation of various refractory organic pollutants, including organic dyes, phenols, antibiotics, and personal care products, with removal ratios higher than 96% after 2 h operation. This can be due to the gradient-doped N-TiO₂ nanobranches, which not only provide bending band structure and defect level derived from the N impurities and O vacancies, resulting the formation of n-n⁺ heterojunctions to improve the charge separation, but also enhance the charge transfer at the liquid-solid interface due to the numerous nanobranches and amorphous coating layers.     

Protective coatings for stainless steel for SOFC applications

In this paper, a coating procedure based on spin coating of metal oxide polymer precursors on stainless steel, which decreases the oxide scale growth rate, is evaluated. The yttrium and cobalt solutions were used as polymer precursors, while a ferritic stainless steel Crofer 22 APU was used for the deposition of protective coatings. The thickness of deposited protective film was about ~500 nm. The effectiveness of protective layer was evaluated by cyclic thermogravimetry, oxide scale electrical conductivity, and X-ray diffractometry. The results show that steel coated with yttrium polymer precursor has better properties than uncoated or cobalt-coated sample.     

Pd cluster nanowires as highly efficient catalysts for selective hydrogenation reactions

Palladium is a key catalyst invaluable to many industrial processes and fine-chemical synthesis. Although recent progress has allowed the synthesis of Pd nanoparticles with various shapes by using different techniques, the facile synthesis of Pd nanocrystals and turning them into a highly active, selective, and stable catalyst systems still remain challenging. Herein, we report the highly selective one-pot synthesis of monodisperse Pd cluster nanowires in aqueous solution; these consist of interconnected nanoparticles and may serve as highly active catalysts because of the enrichment of high index facets on the surface, including {443}, {331}, and {221} steps. For the first time, carbon nanotube and γ-Al(2)O(3) immobilized Pd cluster nanowires showed highly enhanced catalytic performance in the liquid-phase selective hydrogenation of cinnamaldehyde and gas-phase hydrogenation of 1,3butadiene relative to immobilized Pd icosahedra and nanocubes, as well as commercial Pd catalysts.     

CoS2 nanowires supported graphdiyne for highly efficient hydrogen evolution reaction

Transition metal sulfides are an important category for hydrogen evolution reaction(HER).However,only few edge unsaturated sulfurs functionalize as catalytic si...     

Facile synthesis of zirconia supported nanomaterials for efficient photocatalytic applications

The recent study enlightens the synthesis and characterization of zirconia (ZrO₂), Fe-doped ZrO₂ (Fe@ZrO₂), and Ni-doped ZrO₂ (Ni@ZrO₂) catalysts having new-fangled morphology with tuned band gap as photocatalysts for degradation of textile wastewater dyes methylene blue (MB), malachite green (MG), and their mixtures. SEM imaging of Fe@ZrO₂ and Ni@ZrO₂ is interestingly varied from ZrO₂ as well as doping of transition metals greatly affects the morphology of composites. The optimization study depicts that the pH, time (min) and catalyst amount (g) have a direct relation with degradation efficiency, while the dye concentration (mg/L) has an indirect relation as well. The photocatalytic studies depict that the degradation of MB and MG follows oxidation pathway via hydroxyl radicals (OH^•) and holes. Reusability of catalysts corresponds to a little decrease in degradation efficiency in the first two cycles and decreases to about ∼10% (Ni@ZrO₂) and ∼12% (Fe@ZrO₂) in next three cycles.     

Performance of a photocatalytic hybrid system coupled with a stainless steel membrane for removal of humic acid

The objective of this study was to evaluate the performance of a photocatalysis/H₂O₂/metal membrane hybrid system in the degradation of humic acid. A metal membrane of nominal pore size 0.5 μm was used in the experiment for separation of TiO₂ particles. Hydrogen peroxide was tested as an oxidant. The efficiency of removal of COD_Cr and color increased rapidly for initial hydrogen peroxide concentrations up to 50 mg L⁻¹. The efficiency of removal of COD_Cr and color by 50 mg L⁻¹ initial hydrogen peroxide concentration was approximately 95 and 98%, respectively. However, addition of hydrogen peroxide over 50 mg L⁻¹ inhibited the efficiency of the system. Addition of hydrogen peroxide to a UV/TiO₂ system enhanced efficiency of removal of COD_Cr and color compared with no addition of hydrogen peroxide. This may be ascribed to capture electrons ejected from TiO₂ and to the production of OH radicals. Application of the metal membrane in the UV/TiO₂/H₂O₂ system enhanced the efficiency of removal of COD_Cr and color because of adsorption by the metal membrane surface and the production of OH radicals. By application of a metal membrane with a nominal pore size of 0.5 μm, TiO₂ particles were effectively separated from the treated water by metal membrane rejection. The photocatalytic metal membrane had much less resistance than the humic acid, TiO₂, and humic acid/TiO₂ because of the degradation of humic acid by the photocatalytic reaction.     

Preparation and measurement of properties of BiOBr/BiOCl/PANI ternary nanocomposite for highly efficient visible light photocatalytic applications

In this paper, we report the synthesis of the BiOBr/BiOCl/PANI ternary nanocomposite using a simple co-precipitation method. The modified photocatalyst produced was characterized by the FT-IR, FE-SEM equipped with EDS (as a Map), TEM, XRD, PL, Raman, and UV–Vis DRS analytical techniques. The synergetic effect of PANI and surface defects in nanoplates can prolong the recombination rate of photo-generated charge carriers. Thus, photocatalytic and photoelectrochemical activities of samples have been studied. Then, the methyl orange (MO) degradation performance of PANI/BiOBr and BiOBr/BiOCl/PANI was investigated under visible light irradiation. The lamp used to simulate sunlight in this photocatalytic study process was power down white light (5-W LED), less reported. The results got exhibited that the as-prepared BiOBr/BiOCl/PANI (90:10, Bi:PANI) nanocomposite showed a higher photocatalytic efficiency. Based on the scavenger tests, ^·O₂^? played a significant role in the degradation of MO. The connection between BiOBr, BiOCl, and PANI improved photocatalytic activity, which enhanced migration rate of the photo-generated electrons besides limiting the recombination of photo-generated electron–hole pairs.

     

Fabrication of polydiacetylene nanowires by associated self-polymerization and self-assembly processes for efficient field emission properties

The paper described here concerns a challenge of general interest for producing a novel structure of a polymer aggregate, the achievement of nanowires with controlled diameters. We provide a strategy for fabricating a supramolecular polymer, in which ordered polydiacetylene nanowires can be obtained by associated self-polymerization and self-assembly processes. The polymer nanowire film shows excellent field emission properties with the turn-on field of 8.2 V/mum at 10 muA/cm2 and the maximum current density of 5 mA/cm2 at an applied field of 15 V/mum.     

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

Niobium doping increases the visible light adsorption of titanate nanoflakes, which greatly enhances the photocatalytic activity for ibuprofen elimination.     

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

In this study, a novel class of niobium (Nb) doped titanate nanoflakes (TNFs) are fabricated through a one-step hydrothermal method. Nb doping affects the curving of titanate nanosheet, leading to the formation of nanoflake structure. In addition, Nb⁵⁺ filled in the interlayers of [TiO₆] alters the light adsorption property of pristine titanate. The band gap of Nb-TNFs is narrowed to 2.85 eV, while neat titanate nanotubes (TNTs) is 3.4 eV. The enhanced visible light adsorption significantly enhances the visible-light-driven activity of Nb-TNFs for ibuprofen (IBP) degradation. The pseudo-first order kinetics constant for Nb-TNFs is calculated to be 1.04 h^?1, while no obvious removal is observed for TNTs. Photo-generated holes (h⁺) and hydroxyl radicals (OH) are responsible for IBP degradation. The photocatalytic activity of Nb-TNFs depends on pH condition, and the optimal pH value is found to be 5. In addition, Nb-TNFs exhibited superior photo-stability during the reuse cycles. The results demonstrated Nb-TNFs are very promising in photocatalytic water purification.     

Constructing recyclable photocatalytic BiOBr/Ag nanowires/cotton fabric for efficient dye degradation under visible light

In this study, a highly-efficient photocatalytic and recyclable BiOBr/Ag nanowires (AgNW)/cotton fabric (CF) composite was fabricated by successive ionic layer adsorption and reaction (SILAR) for rapid treatment of dye wastewater. The integration of AgNW and BiOBr aims to establish a channel for faster and easier charge transfer to enhance the photocatalytic performance. The chemical structure and morphology of BiOBr/AgNW/CF, as well as its photo-degradation of Rhodamine B (RhB) under visible light radiation were explored. Results reveal that BiOBr/AgNW/CF exhibits remarkably enhanced photocatalytic activity over BiOBr/CF, which degrades 97 % of RhB within 90 min. BiOBr/AgNW/CF still maintains 88 % of photocatalytic degradation capacity after five reusing cycles due to the effective encapsulation of BiOBr that protects AgNW from oxidation. Photoluminescence, electron spin resonance, and free radical trapping experiments confirm that the separation efficiency of photo-generated electron-hole pairs plays an important role in improving photocatalytic performance. In all, this work exhibits great potential in the development of textile-based photocatalytic materials that integrates two significant merits, the high degradation efficiency and easy recovery.     

基于表面优先型相变过程构建TiO_2(B)/锐钛矿异相结纳米纤维及其光催化性能（英文）

近年来,随着光催化研究的逐渐深入,人们发现有效的电荷分离往往是提高半导体光催化材料活性的关键步骤.其中,在多晶相半导体材料中构建异相结结构是提高其活性的最有效途径之一.在TiO_2四种稳定晶相中,Ti O2(B)是发现最晚且研究较少的,并且目前对它的研究主要集中于锂离子电池方面,而在光催化领域中研究较少.然而,该材料特殊的晶相结构带来的各向异性和较大的比表面积都表明其在光催化领域同样具有潜在应用前景.本文通过三步合成法,包括水热过程、离子交换、退火过程,研究了TiO_2(B)向锐钛矿转变的相变过程,同时构建了具有TiO_2(B)/锐钛矿异相结结构的纳米线.在材料退火过程中,通过X射线衍射(XRD)和表面灵敏的紫外拉曼光谱(UV-Raman)分别监测了样品体相和表面相的晶相结构变化过程.发现了XRD与UV-Raman结果的不同步性.同时,通过对样品扫描电镜和透射电镜的形貌表征可知,TiO_2(B)纳米线在退火过程中部分结构发生坍塌,且逐渐转化成锐钛矿相,而相变过程很可能首先发生在坍塌结构处.高分辨电镜结果表明,纳米线中同时存在着TiO_2(B)结构和锐钛矿结构,并形成很好的异相结.根据相结构变化和形貌观察结果,我们推测TiO_2(B)向锐钛矿转变过程为表面优先型的相变过程,即材料表面相先于体相先发生相变过程,由此得到的材料表面相含有较多的锐钛矿,而体相中含有较多的TiO_2(B).为了验证构建的异相结材料的光催化活性,采用光催化产氢和降解污染物双重反应对样品进行了表征.结果发现,单独的TiO_2(B)材料活性较锐钛矿材料相差较多,但其混相结构能较大幅度地提高光催化活性.其中,通过逐渐退火过程形成的体相为24%的TiO_2(B)、表面为100%的锐钛矿相的催化剂活性最高,其产氢活性可达4.82 mmol/(h?g),降解污染物反应速率常数为0.0402 min~(-1).采用光电流测试、电化学阻抗和荧光光谱表征了材料在光催化过程中的载流子动力学行为.结果表明,最优活性的催化剂中体相的异相结结构对光生电荷的分离、传输都起到良好地促进作用,而表面的锐钛矿相主要负责高活性的表面反应,二者共同对高活性的光催化反应起到推动作用.     

Optimized design of novel Pt decorated 3D BiOBr flower-microsphere synthesis for highly efficient photocatalytic properties

3D BiOBr flower-microspheres decorated with small amount (0.02–0.5 wt%) of Pt nanoparticles were successfully prepared via new electrostatic-adsorption-assisted light-reduction route. The as-prepared samples were characterized by XRD, SEM, HRTEM, EDS, XPS, UV–Vis DRS, PL, and photocurrent measurements. The photocatalytic activities were tested through the photocatalytic degradation of Bisphenol A (BPA) under visible light (420 nm?<?λ?<?680 nm) and simulated sunlight (320 nm?<?λ?<?680 nm) irradiation. The results indicate that Pt loading do not change the structural morphologies and particle sizes of BiOBr flower-microspheres, but there exists an enhanced photocurrent effect, greatly achieving the highly efficient photocatalytic activity of BiOBr under visible-light and simulated sunlight irradiation. 0.2 wt% Pt/BiOBr sample reveals the highest photocatalytic activity for the degradation on BPA with almost 92% under 10 min, much better than pure BiOBr and (P25) TiO₂. The presence of synergistic effect between Pt⁴⁺ and Pt⁰ has vital impact on the electron capture and transfer from the semiconductor to noble metal, preventing the fast electron/hole recombination and participating in the multi-electron reduction of O₂, and, consequently, achieving the formation of effective photocatalytic active species. Our findings should provide the fundamental data for making further research efforts in the hot topic on the monatomic Pt-modified photocatalyst systems.     

超疏水超亲油不锈钢网的制备工艺优化及其性能研究

采用十六烷基三甲氧基硅烷(HDTMS)对纳米二氧化硅(Nano-SiO2)进行疏水改性,通过一步浸渍法将疏水Nano-SiO2负载在化学刻蚀后的不锈钢网表面.以空气中水的静态接触角为评价手段,优化制备工艺并研究改性剂HDTMS的用量、改性时间、改性温度以及浸渍时间对疏水处理后不锈钢网的影响.采用透射电子显微镜(TEM)...     

A carbon-rich g-C3N4 with promoted charge separation for highly efficient photocatalytic degradation of amoxicillin

A novel carbon-rich g-C₃N₄ nanosheets with large surface area was prepared by facile thermal polymerization method using urea and 1,3,5-cyclohexanetriol. Plenty of carbon-rich functional groups were introduced into the surface layers of g-C₃N₄, which constructed the built-in electric field (BIEF) and resulted in improved charge separation; therefore, the carbon-rich g-C₃N₄ displayed superior photocatalytic activity for amoxicillin degradation under solar light. The contaminant degradation mechanism was proposed based on radical quenching experiments, intermediates analysis and density functional theory (DFT) calculation. Moreover, the reusing experiments showed the high stability of the material, and the amoxicillin degradation under various water matrix parameters indicated its high applicability on pollutants treatment, all of which demonstrated its high engineering application potentials.     

Fabrication of minimal capital-intensive scratch-resistant and hydrophobic tungsten oxide film on stainless steel through spray pyrolysis

In this contribution, a pure and robust tungsten oxide (WO₃) film was accomplished on stainless steel (SS) substrate at 400°C through a minimal capital intensive, simplistic spray pyrolysis method by utilizing a precursor comprising tungsten hexachloride and 2-methoxyethanol. Thermal analysis revealed the precursor's thermal decomposition and crystallization at ~230°C and 255°C, respectively. The fabricated polycrystalline (monoclinic crystal structured) film was uniform and dense in nature, exhibiting surface porosity and average surface roughness of 4.7 % and 15.9 nm, respectively. The average grain size and thickness of film were 360 ± 70 nm and ~3.6 μm, respectively. W, O elemental presence with a close atomic ratio of 1:3 on the film's surface was acquired along with 91 % lattice oxygen. Regardless of applied normal load in the range of 5 to 15 N, an increment of ~22 % in scratch hardness was gained in WO₃-coated SS compared to uncoated one. Hydrophilic natured WO₃ film (water contact angle, WCA, of ~31°) was efficaciously transformed into hydrophobic (WCA, 136°) by chemical modification with octadecyltrichlorosilane to create a self-assembled monolayer on the surface of the film. The hydrophobicity of octadecyltrichlorosilane (OTS)-treated film was found to be preserved even after 100 days.     

Atomic insights of electronic states engineering of GaN nanowires by Cu cation substitution for highly efficient lithium ion battery

Electronic engineering of gallium nitride(Ga N) is critical for enhancement of its electrode performance.In this work, copper(Cu) cation substituted Ga N(Cu-Ga N) nanowires were fabricated to understand the electronically engineered electrochemical performance for Li ion storage. Cu cation substitution was revealed at atomic level by combination of X-ray photoelectron spectroscopy(XPS), X-ray absorption fine structure(XAFS), density functional theory(DFT) simulation, and so forth. The Cu-Ga N el...     

Metal oxides composite electrode with high areal capacitance formed by thermal oxidation of stainless steel mesh

Journal of Solid State Electrochemistry - The motivation of this study is to understand the usability of annealed stainless steel mesh obtained by a straightforward method for energy storage...