共查询到20条相似文献，搜索用时 15 毫秒
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Letizia Liccardo Matteo Bordin Polina M. Sheverdyaeva Matteo Belli Paolo Moras Alberto Vomiero Elisa Moretti 《Advanced functional materials》2023,33(22):2212486
Nanostructured TiO2 is one of the best materials for photocatalysis, thanks to its high surface area and surface reactivity, but its large energy bandgap (3.2 eV) hinders the use of the entire solar spectrum. Here, it is proposed that defect-engineered nanostructured TiO2 photocatalysts are obtained by hydrogenation strategy to extend its light absorption up to the near-infrared region. It is demonstrated that hydrogenated or colored TiO2 hollow spheres (THS) composed of hierarchically assembled nanoparticles result in much broader exploitation of the solar spectrum (up to 1200 nm) and the engineered surface enhances the photogeneration of charges for photocatalytic processes. In turn, when applied for photodegradation of a targeted drug (Ciprofloxacin) this results in 82% degradation after 6 h under simulated sunlight. Valence band analysis by photoelectron spectroscopy revealed the presence of oxygen vacancies, whose surface density increases with the hydrogenation rate. Thus, a tight correlation between degree of hydrogenation and photocatalytic activity is directly established. Further insight comes from electron paramagnetic resonance, which evidences bulk Ti3+ centers only in hydrogenated THS. The results are anticipated to disclose a new path toward highly efficient photocatalytic titania in a series of applications targeting water remediation and solar fuel production. 相似文献
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Yijun Chen Qing Zhang Yi Zhong Pingdong Wei Xuejie Yu Junchao Huang Jie Cai 《Advanced functional materials》2021,31(38):2104368
Currently, the world is facing the problems of the gradual depletion of non-renewable fossil resources and the severe harm of non-degradable plastic waste to the land and marine ecological environment. Because of the rapid increase in the demand for fiber materials, the development of high-performance biomass-based fibers has emerged as an important research topic to reduce the reliance on petroleum-based synthetic fibers. In this study, a novel green wet-spinning strategy is used for the fabrication of super-strong and super-stiff chitosan filaments from an aqueous KOH/urea solution using a two-step drawing process. The highly ordered hierarchical structure of the resulting filaments contributes to their excellent mechanical properties. The tensile strength and Young's modulus of the chitosan filaments are 878 ± 123 MPa and 44.7 ± 12.3 GPa, respectively, and these values are comparable to those of spider silk and bacterial cellulose. The chitosan filaments prepared in this study are superior to low-density steel in terms of the specific strength and modulus. The green and scalable strategy proposed in this study will broaden the application range of chitosan filaments in flexible bioelectronics, biomaterials, and textiles. 相似文献
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Jianguo Zhou Zhenlong Sun Mingqi Chen Jitong Wang Wenming Qiao Donghui Long Licheng Ling 《Advanced functional materials》2016,26(29):5368-5375
Hollow carbon spheres (HCSs) represent a special class of functional materials, to which intense interest has been paid in the fields of materials science and chemistry. A major problem with these materials is the lack of sufficient particle engineering and mechanical strength for practical applications and the difficulty of up‐scaling. Herein, we report a general, template‐free, phase‐separation approach, in which the liquid–liquid phase‐inversion process and a gas‐foaming process are coupled for the first time, for fast and continuous processing of uniform HCSs. The obtained HCSs have particle sizes on the millimeter scale, and a hierarchical structure with an interpenetrating, open‐porous, carbon shell and huge external voids, therefore permitting rapid transport of molecules into, throughout, and out of the hollow structure. By evenly dispersing the CNTs in the precursor solution, CNT‐reinforced HCSs can be achieved with significantly enhanced mechanical strength, hydrophobicity, and electronic and thermal properties. The resulting CNT‐reinforced HCSs offer a viable route to remove the engine oil from water in a fixed‐bed system. Moreover, these floatable HCSs can receive and convert sunlight to heat at the water–air interface, resulting in a great enhancement in solar evaporation rate compared to conventional bulk heating schemes. 相似文献
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A Unique Disintegration–Reassembly Route to Mesoporous Titania Nanocrystalline Hollow Spheres with Enhanced Photocatalytic Activity 
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下载免费PDF全文 Xin Wang Licheng Bai Hongyan Liu Xuefeng Yu Yadong Yin Chuanbo Gao 《Advanced functional materials》2018,28(2)
A novel disintegration–reassembly route is reported for the synthesis of mesoporous TiO2 nanocrystalline hollow spheres with controlled crystallinity and enhanced photocatalytic activity. In this unique synthesis strategy, it is demonstrated that sol–gel‐derived mesoporous TiO2 colloidal spheres can be disintegrated into discrete small nanoparticles that are uniformly embedded in the polymer (polystyrene, PS) matrix by surface‐induced photocatalytic polymerization. Subsequent reassembly of these TiO2 nanoparticles can be induced by an annealing process after further coating of a resorcinol–formaldehyde (RF) resin, which forms self‐supported hollow spheres of TiO2 at the PS/RF interface. The abundant phenolic groups on the RF resin serve as anchoring sites for the TiO2 nanoparticles, thus enable the reassembly of the TiO2 nanoparticles and prevent their sintering during the thermal crystallization process. This unique disintegration–reassembly process leads to the formation of self‐supported TiO2 hollow spheres with relatively large surface area, high crystallinity, and superior photocatalytic activity in dye degradation under UV light irradiation. 相似文献
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Benjamin W. Riblett Nicola L. Francis Margaret A. Wheatley Ulrike G. K. Wegst 《Advanced functional materials》2012,22(23):4920-4923
Successful spinal cord repair is thought to be promoted with hierarchically structured scaffolds. These should combine aligned porosity with additional linear features on the micrometer scale to guide axons across multiple length scales. Such scaffolds are generated through the carefully controlled directional solidification of an aqueous biopolymer solution, followed by lyophilization. Under specific freezing conditions this yields a highly regular and aligned lamellar architecture. This architecture exhibits uniform ridges of controlled height and width on the lamellar surface. These ridges run parallel to the pore axis, serving as secondary guidance features. The ridges are capable of linearly aligning 62.4% of chick dorsal root ganglia neurites to within ±10° of the ridge direction. Notably, neurites sprouting perpendicular to the ridge are guided into alignment with these microridged features. 相似文献
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Wenguang Tu Yong Zhou Qi Liu Zhongping Tian Jun Gao Xiaoyu Chen Haitao Zhang Jianguo Liu Zhigang Zou 《Advanced functional materials》2012,22(6):1215-1221
Robust hollow spheres consisting of molecular‐scale alternating titania (Ti0.91O2) nanosheets and graphene (G) nanosheets are successfully fabricated by a layer‐by‐layer assembly technique with polymer beads as sacrificial templates using a microwave irradiation technique to simultaneously remove the template and reduce graphene oxide into graphene. The molecular scale, 2D contact of Ti0.91O2 nanosheets and G nanosheets in the hollow spheres is distinctly different from the prevenient G‐based TiO2 nanocomposites prepared by simple integration of TiO2 and G nanosheets. The nine times increase of the photocatalytic activity of G‐Ti0.91O2 hollow spheres relative to commercial P25 TiO2 is confirmed with photoreduction of CO2 into renewable fuels (CO and CH4). The large enhancement in the photocatalytic activity benefits from: 1) the ultrathin nature of Ti0.91O2 nanosheets allowing charge carriers to move rapidly onto the surface to participate in the photoreduction reaction; 2) the sufficiently compact stacking of ultrathin Ti0.91O2 nanosheets with G nanosheets allowing the photogenerated electron to transfer fast from the Ti0.91O2 nanosheets to G to enhance lifetime of the charge carriers; and 3) the hollow structure potentially acting as a photon trap‐well to allow the multiscattering of incident light for the enhancement of light absorption. 相似文献
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采用数值模拟方法研究了熔铸炸药常压和加压条件下凝固过程中的温度场,得到了温度的冷却曲线、固液界面的变化过程以及缩孔缩松缺陷可能出现的位置。常压条件下关注位置的计算温度值与实测温度值误差在10%以内;加压在5~20个大气压之间时,随着压力的增大,炸药件的缩孔缩松缺陷显著减少。模拟结果表明加压凝固工艺能有效地消除熔铸炸药的缩孔缩松缺陷。 相似文献
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Chunjuan Tang Yuning Liu Chang Xu Jiexin Zhu Xiujuan Wei Liang Zhou Liang He Wei Yang Liqiang Mai 《Advanced functional materials》2018,28(3)
The high theoretical capacity and natural abundance of SiO2 make it a promising high‐capacity anode material for lithium‐ion batteries. However, its widespread application is significantly hampered by the intrinsic poor electronic conductivity and drastic volume variation. Herein, a unique hollow structured Ni/SiO2 nanocomposite constructed by ultrafine Ni nanoparticle (≈3 nm) functionalized SiO2 nanosheets is designed. The Ni nanoparticles boost not only the electronic conductivity but also the electrochemical activity of SiO2 effectively. Meanwhile, the hollow cavity provides sufficient free space to accommodate the volume change of SiO2 during repeated lithiation/delithiation; the nanosheet building blocks reduce the diffusion lengths of lithium ions. Due to the synergistic effect between Ni and SiO2, the Ni/SiO2 composite delivers a high reversible capacity of 676 mA h g?1 at 0.1 A g?1. At a high current density of 10 A g?1, a capacity of 337 mA h g?1 can be retained after 1000 cycles. 相似文献
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Geon Dae Moon Ji Bong Joo Michael Dahl Heejung Jung Yadong Yin 《Advanced functional materials》2014,24(6):848-856
The nitridation of hollow TiO2 nanoshells and their layered assembly into electrodes for electrochemical energy storage are reported. The nitridated hollow shells are prepared by annealing TiO2 shells, produced initially using a sol–gel process, under an NH3 environment at different temperatures ranging from 700 to 900 °C, then assembled to form a robust monolayer film on a water surface through a quick and simple assembly process without any surface modification to the samples. This approach facilitates supercapacitor cell design by simplifying the electrochemical electrode structure by removing the need to use any organic binder or carbon‐based conducting materials. The areal capacitance of the as‐prepared electrode is observed to be ≈180 times greater than that of a bare TiO2 electrode, mainly due to the enhanced electrical conductivity of the TiN phase produced through the nitridation process. Furthermore, the electrochemical capacitance can be enhanced linearly by constructing an electrode with multilayered shell films through a repeated transfer process (0.8 to 7.1 mF cm–2, from one monolayer to 9 layers). Additionally, the high electrical conductivity of the shell film makes it an excellent scaffold for supporting other psuedocapacitive materials (e.g., MnO2), producing composite electrodes with a specific capacitance of 743.9 F g–1 at a scan rate of 10 mV s–1 (based on the mass of MnO2) and a good cyclic stability up to 1000 cycles. 相似文献
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Silica hollow nanosphere colloidal crystals feature a uniquely well‐defined structure across multiple length scales. This contribution elucidates the intricate interplay between structure and atmosphere on the effective thermal diffusivity as well as the effective thermal conductivity. Using silica hollow sphere assemblies, one can independently alter the particle geometry, the density, the packing symmetry, and the interparticle bonding strength to fabricate materials with an ultralow thermal conductivity. Whereas the thermal diffusivity decreases with increasing shell thickness, the thermal conductivity behaves inversely. However, the geometry of the colloidal particles is not the only decisive parameter for thermal insulation. By a combination of reduced packing symmetry and interparticle bonding strength, the thermal conductivity is lowered by additionally 70% down to only 8 mW m?1 K?1 in vacuum. The contribution of gaseous transport, even in these tiny pores (<200 nm), leads to minimum thermal conductivities of ≈35 and ≈45 mW m?1 K?1 for air and helium atmosphere, respectively. The influence of the individual contributions of the solid and (open‐ and closed‐pore) gaseous conductions is further clarified by using finite element modeling. Consequently, these particulate materials can be considered as a non‐flammable and dispersion‐processable alternative to commercial polymer foams. 相似文献
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Xiaoshuang Chen Huihui Yang Guangbo Liu Feng Gao Mingjin Dai Yunxia Hu Hongyu Chen Wenwu Cao PingAn Hu Wenping Hu 《Advanced functional materials》2018,28(8)
Well‐defined hollow spherical nanoshell arrays of 2D transitional metal dichalcogenide (TMDC) nanomaterials for MoSe2 and MoS2 are grown via chemical vapor deposition technique for the first time. The hollow sphere arrays display the uniform dimensions of ≈450 nm with the shell thickness of ≈10 nm. The unique hollow sphere architecture with increased active surface area is forecasted to supply more efficient route to improve light‐harvesting efficiency through repeated light reflection and scattering inside the hollow structure without decay of response and recovery speed, because exceptional “SP–SP” junction barriers conducting mechanism can facilitate carriers tunneling and transport during the electron transfer procedure within the present particular structure. The MoSe2 hollow sphere photodetector exhibits an outstanding responsivity (8.9 A W?1), which is tenfold higher than that for MoSe2 compact film (0.9 A W?1), fast response and recovery speed, and good durability under illumination wavelength of 365 nm. Meanwhile, MoSe2 hollow sphere arrays on flexible polyethylene terephthalate substrates reveal excellent bending stability. Therefore, this research indicates that unique hollow sphere architecture of 2D TMDC materials will be an anticipated avenue for efficient photodetector devices with far‐ranging capability. 相似文献
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Liu Yang Onur Kaba Peng Wang Dietmar Auhl Astrid Haibel Oliver Görke Claudia Fleck 《Advanced functional materials》2024,34(35):2305927
Bioinspired, graded structures with hierarchical porosity, combining high surface area with low density, are attractive for a wide range of applications. Local adaptation of properties makes it possible to fine-tune their strength and degradation kinetics over time. Production of such structures is, however, still scientifically and technically challenging. A versatile approach for fabricating hierarchical, porous structures from water-glass (WG), exploiting its inherent foaming ability in conjunction with robocasting, for applications such as, bone-replacement scaffolds, is presented. The unique processing route that is proposed uses a purely inorganic, mouldable sodium silicate hydrogel based on WG as ink for robocasting, which makes it cost-effective and highly environmentally friendly. The WG-based hydrogels can be used in a pure state, and also as carrier systems, e.g., for tricalcium phosphate. Following heat treatment at a relatively low temperature of 450 °C, the robocast parts develop hierarchical porosities. Multi-microscale porosity is created due to foaming during heating, in addition to the macroscale porosity designed during robocasting. The suggested process opens up a powerful alternative to fabrication routes presently available for hierarchically porous structures. 相似文献
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Shengjie Peng Linlin Li Huiteng Tan Ren Cai Wenhui Shi Chengchao Li Subodh G. Mhaisalkar Madhavi Srinivasan Seeram Ramakrishna Qingyu Yan 《Advanced functional materials》2014,24(15):2155-2162
We demonstrate in this paper facile synthesis of CoS2 and NiS2 hollow spheres with various interiors through a solution‐based route. The obtained CoS2 microspheres constructed by nanosheets display a three‐dimensional architecture with solid, yolk‐shell, double‐shell, and hollow interiors respectively, with continuous changes in specific surface areas and pore‐size distributions. Especially, the CoS2 hollow spheres demonstrate excellent supercapacitive performance including high specific capacitance, good charge/discharge stability and long‐term cycling life, owing to the greatly improved faradaic redox reaction and mass transfer. Furthermore, CoS2 hollow spheres exhibit superior electrocatalytic activity for disulfide/thiolate (T2/T?) redox electrolyte in dye‐sensitized solar cells (DSCs). Therefore, this work provides a promising approach for the design and synthesis of structure tunable materials with largely enhanced supercapacitor behavior, which can be potentially applied in energy storage devices. 相似文献
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Hollow Spheres: MS2 (M = Co and Ni) Hollow Spheres with Tunable Interiors for High‐Performance Supercapacitors and Photovoltaics (Adv. Funct. Mater. 15/2014) 下载免费PDF全文
下载免费PDF全文 Shengjie Peng Linlin Li Huiteng Tan Ren Cai Wenhui Shi Chengchao Li Subodh G. Mhaisalkar Madhavi Srinivasan Seeram Ramakrishna Qingyu Yan 《Advanced functional materials》2014,24(15):2154-2154
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Native and carbonized freeze-cast bacterial cellulose-alginate (BC-ALG) foams possess an ice-templated honeycomb-like architecture with remarkable properties. Their unique pore morphology consists of two levels of porosity: 20–50 µm diameter pores between, and 0.01–10 µm diameter pores within the cell-walls. The mechanical properties of the BC-ALG foams, a Young's modulus of up to 646.2 ± 90.4 kPa and a compressive yield strength of up to 37.1 ± 7.9 kPa, are high for their density and scale as predicted by the Gibson–Ashby model for cellular materials. Carbonizing the BC-ALG foams in an inert atmosphere at 1000–1200 °C in a second processing step, both pore morphology and mechanical properties of the BC-ALG remain well preserved with specific mechanical properties that are higher than those reported in the literature for similar foams. Also the electrical conductivity of the BC-ALG foams is high at 1.68 ± 0.04 S cm?1 at a density of only 0.055 g cm?3, and is found to increase with density as predicted, and as a function of the degree of carbonization determined by both carbonization temperature and atmosphere. The property profile makes freeze-cast BC-ALG foams and their carbonized foams attractive for energy applications and as a sorbent. 相似文献
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Yajiao Su Molin Qin Jinglin Kong Quanguo Zhai Daqiang Yuan Zhongshan Liu Yu Fang 《Advanced functional materials》2024,34(33):2400433
Solvothermal synthesis is the predominant method for creating new structured covalent organic frameworks (COFs), yet it grapples with challenges in controlling shape and morphology. This issue is attributed to the unregulated solvent-feeding process, which results in rapid polymerization and uncontrolled phase separation. Consequently, a two-step solvent-feeding process is reported for the solvothermal shaping of imine-linked COF monoliths with hierarchical porosity. The synthesis conditions for COF powders reported in existing literature are directly utilized without extensive optimization; however, solvents are divided into two segments prior to feeding. A minor segment of solvents is employed to dissolve monomers, which polymerize in situ to form amorphous monoliths. Subsequently, the remaining organic solvent, along with an acetic acid aqueous solution, is added for crystallization. The versatility of this two-step feeding process in producing COF monoliths is illustrated. The high-quality COF monoliths demonstrate benzene uptakes ranging from 6.0 to 16.8 mmol g−1 at 298 K. This study confirms that the two-step solvent feeding process can be effectively integrated with the conventional solvothermal method to enhance the solution-processability of COFs. It is anticipated that this modified solvothermal approach can readily shape COFs to meet practical application requirements. 相似文献