Amorphous structure

非晶结构
  • 文章类型: Journal Article
    在碱性水电解和阴离子交换膜水电解技术中,在水离解步骤期间,阴极处的析氢反应(HER)受到高能势垒的显著限制。本研究采用相位工程策略来构建由结晶Ni4W和非晶WOx组成的异质结构,旨在增强碱性条件下HER的催化性能。这项工作系统地调制W在异质结构的非晶WOx内的氧化态,以调节相界的电子态,与水解离步骤相关的能量屏障,以及碱性HER过程中中间体的吸附/解吸性能。优化后的催化剂,Ni4W/WOx-2,具有W的准金属态,由非晶WOx中的低氧含量配位,表现出优异的催化性能(22mV@10mAcm-2),优于商用Pt/C(30mV@10mAcm-2)。此外,操作X射线吸收光谱分析和理论计算表明,无定形WOx中优化的W原子充当水解离的活性位点,而晶体Ni4W中附近的Ni原子促进了H2的释放。这些发现为设计用于能量转换的高效异质结构材料提供了有价值的见解。
    In alkaline water electrolysis and anion exchange membrane water electrolysis technologies, the hydrogen evolution reaction (HER) at the cathode is significantly constrained by a high energy barrier during the water dissociation step. This study employs a phase engineering strategy to construct heterostructures composed of crystalline Ni4W and amorphous WOx aiming to enhance catalytic performance in the HER under alkaline conditions. This work systematically modulates the oxidation states of W within the amorphous WOx of the heterostructure to adjust the electronic states of the phase boundary, the energy barriers associated with the water dissociation step, and the adsorption/desorption properties of intermediates during the alkaline HER process. The optimized catalyst, Ni4W/WOx-2, with a quasi-metallic state of W coordinated by a low oxygen content in amorphous WOx, demonstrates exceptional catalytic performance (22 mV@10 mA cm-2), outperforming commercial Pt/C (30 mV@10 mA cm-2). Furthermore, the operando X-ray absorption spectroscopy analysis and theoretical calculations reveal that the optimized W atoms in amorphous WOx serve as active sites for water dissociation and the nearby Ni atoms in crystalline Ni4W facilitated the release of H2. These findings provide valuable insights into designing efficient heterostructured materials for energy conversion.
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  • 文章类型: Journal Article
    森林是加拿大人的主要财富来源,纤维素构成了木纤维的“骨架”。浓H2SO4和NaOH/尿素水溶液是两种可以快速溶解纤维素的有效溶剂。我们的初步实验从这两种溶剂中获得了具有不同机械性能的再生木质纤维素膜。因此,在这里,我们旨在研究水性溶剂对木质纤维素薄膜结构和性能的影响。通过将木质纤维素溶解在64重量%H2SO4溶液(RC-H4)或NaOH/尿素水溶液(RC-N4)中来制备再生纤维素(RC)膜。RC-H4具有较高的抗拉强度(109.78±2.14MPa),更好的折叠耐久性(20-28倍),扭转角(42°)高于RC-N4(62.90±2.27MPa,不可折叠,和12°)。H2SO4溶液中的纤维素含量从3wt%增加到5wt%,导致拉伸强度从102.61±1.99提高到132.93±5.64MPa,并且不影响可折叠性。RC-H4还表现出更好的水蒸气阻隔性能(1.52±0.04×10-7g-1h-1Pa-1),优异的透明度(〜90%的透射率在800纳米),但热稳定性低于RC-N4。这项工作提供了对两种水性溶剂中再生木材纤维素的特殊见解,并有望促进从丰富的林业资源中开发高性能RC膜。
    Forests are a major source of wealth for Canadians, and cellulose makes up the \"skeleton\" of wood fibers. Concentrated H2SO4 and NaOH/urea aqueous solutions are two efficient solvents that can rapidly dissolve cellulose. Our preliminary experiment obtained regenerated wood cellulose films with different mechanical properties from these two solvents. Therefore, herein, we aim to investigate the effects of aqueous solvents on the structure and properties of wood cellulose films. Regenerated cellulose (RC) films were produced by dissolving wood cellulose in either 64 wt% H2SO4 solution (RC-H4) or NaOH/urea aqueous solution (RC-N4). RC-H4 showed the higher tensile strength (109.78 ± 2.14 MPa), better folding endurance (20-28 times), and higher torsion angle (42°) than RC-N4 (62.90 ± 2.27 MPa, un-foldable, and 12°). The increased cellulose contents in the H2SO4 solutions from 3 to 5 wt% resulted in an improved tensile strength from 102.61 ± 1.99 to 132.93 ± 5.64 MPa and did not affect the foldability. RC-H4 also exhibited better water vapor barrier property (1.52 ± 0.04 × 10-7 g m-1 h-1 Pa-1), superior transparency (~90 % transmittance at 800 nm), but lower thermal stability compared to RC-N4. This work provides special insights into the regenerated wood cellulose from two aqueous solvents and is expected to facilitate the development of high-performance RC films from abundant forestry resources.
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  • 文章类型: Journal Article
    预催化剂的设计和相应的电化学重构的合理操纵对于构建用于海水氧化的高耐久性和活性催化剂至关重要。但相当具有挑战性。在这里,首先设计了一种新型的Co2(PS3)@Co2P(标记为CoPS)的核壳催化剂,该催化剂是通过在结晶的钴磷三卤族化合物(Co2(PS3))上外延生长非晶磷化钴(Co2P)作为碱性海水氧化的预催化剂。采用各种表征技术来证明独特的无定形-结晶纳米线结构(CoPS)实现了快速表面重构为活性CoOOH和多种氧阴离子物种(标记为CoPS-R)。理论模拟揭示了原位衍生的氧阴离子(PO42-,COOOH表面的SO32-和SO42-)可以调节Co位点的电子分布,从而优化了析氧反应(OER)中间体在CoOOH上的化学吸附,降低了测定步骤的能障。因此,在碱性天然海水溶液中,重建的CoPS-R催化剂在200和500mAcm-2时OER分别表现出357和402mV的小的过电势,在500毫安cm-2的大电流密度下,500小时内具有令人印象深刻的耐用性,受益于衍生的PO42-的强排斥效应,SO32-和SO42-氧阴离子。这项工作为理解结构-组成-活性的关系提供了新的见解,并开发了一种新的方法来构建用于海水电解的有效和强大的OER催化剂。
    The design of pre-catalysts and the rational manipulation of corresponding electrochemical reconstruction are vitally important to construct the highly durable and active catalysts for seawater oxidation, but rather challenging. Herein, a novel core-shell catalyst of Co2(PS3)@Co2P (labeled as CoPS) by epitaxial growth of amorphous cobalt phosphide (Co2P) on crystalline cobalt phosphorous trichalcogenide (Co2(PS3)) is firstly designed as a pre-catalyst for alkaline seawater oxidation. Various characterization techniques are employed to demonstrate that the unique amorphous-crystalline nanowire structure (CoPS) achieves the rapid surface reconstruction into active CoOOH and diversiform oxyanions species (labeled as CoPS-R). Theoretical simulations uncover that the in situ derived oxyanions (PO42-, SO32- and SO42-) on the surface of CoOOH can tune the electron distribution of Co site, thereby optimizing the chemisorption of oxygen evolution reaction (OER) intermediates on CoOOH and reducing the energy barrier of determining step. Consequently, in an alkaline natural seawater solution, the reconstructed CoPS-R catalyst exhibits small overpotentials of 357 and 402 mV for OER at 200 and 500 mA cm-2, respectively, together with an impressive durability over 500 h at a large current density of 500 mA cm-2 benefiting from the strong repulsive effect of the derived PO42-, SO32- and SO42- oxyanions. This work offers a new insight for comprehending the relationship of structure-composition-activity and develops a new approach toward the construction of efficient and robust OER catalysts for seawater electrolysis.
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  • 文章类型: Journal Article
    本研究提出了一种使用人工神经网络(ANN)优化蚕豆生物量(FBB)的半固态发酵(S-SSF)的新型高效普鲁兰多糖生产方法。该方法在10.82天内达到破纪录的支链淀粉产量为36.81mg/g,大大超过以前的结果。此外,这项研究通过表征纯化的普鲁兰超越了产量优化,揭示其独特的性质,包括热稳定性,非晶结构,和抗氧化活性。能量色散X射线光谱和扫描电子显微镜证实了其化学组成和独特的形态。这项研究引入了一种开创性的神经网络组合和全面的表征,为在S-SSF条件下在FBB上生产可持续且具有成本效益的支链淀粉铺平了道路。此外,该研究表明,在使用尖孢镰刀菌合成过程中,普鲁兰多糖与Ag@TiO2纳米颗粒成功整合。这种新颖的方法通过改变纳米粒子的表面性质,显著提高了纳米粒子的稳定性和功效。导致对各种人类病原体的抗菌活性显着提高。这些发现展示了低成本的生产介质,以及普鲁兰的广泛潜力不仅在于其固有特性,而且还在于其显着提高纳米材料性能的能力。这一突破为各个领域的不同应用打开了大门。
    This study presents a novel and efficient approach for pullulan production using artificial neural networks (ANNs) to optimize semi-solid-state fermentation (S-SSF) on faba bean biomass (FBB). This method achieved a record-breaking pullulan yield of 36.81 mg/g within 10.82 days, significantly exceeding previous results. Furthermore, the study goes beyond yield optimization by characterizing the purified pullulan, revealing its unique properties including thermal stability, amorphous structure, and antioxidant activity. Energy-dispersive X-ray spectroscopy and scanning electron microscopy confirmed its chemical composition and distinct morphology. This research introduces a groundbreaking combination of ANNs and comprehensive characterization, paving the way for sustainable and cost-effective pullulan production on FBB under S-SSF conditions. Additionally, the study demonstrates the successful integration of pullulan with Ag@TiO2 nanoparticles during synthesis using Fusarium oxysporum. This novel approach significantly enhances the stability and efficacy of the nanoparticles by modifying their surface properties, leading to remarkably improved antibacterial activity against various human pathogens. These findings showcase the low-cost production medium, and extensive potential of pullulan not only for its intrinsic properties but also for its ability to significantly improve the performance of nanomaterials. This breakthrough opens doors to diverse applications in various fields.
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  • 文章类型: Journal Article
    金属硫化物由于其结构多样性和高理论容量,是钠离子电池(SIB)的有前途的负极材料,但是,由于结构稳定性差和动力学缓慢而导致的严重容量衰减和低率容量阻碍了它们的实际应用。在这里,由还原氧化石墨烯包裹的钴掺杂非晶VS4(即,Co0.5-VS4/rGO)是通过Co诱导缺陷工程策略开发的,以提高动力学性能。制备的Co0.5-VS4/rGO在10Ag-1以上具有出色的倍率容量,在5Ag-1超过1600次循环时具有出色的循环稳定性,这归因于Co掺杂形成的缺陷,形成的非晶结构和坚固的rGO基底。当使用活性炭阴极时,在钠离子电容器中进一步证实了Co0.5-VS4/rGO阳极的巨大特性。此外,金属掺杂之间的关系,派生的缺陷,无定形结构,并揭示了VS4的钠储存。这项工作为制备无定形功能材料提供了深刻的见解,也探讨了金属硫化物基电极材料在先进电池中的潜在应用。
    Metal sulfides are promising anode materials for sodium-ion batteries (SIBs) due to their structural diversity and high theoretical capacity, but the severe capacity decay and inferior rate capability caused by poor structural stability and sluggish kinetics impede their practical applications. Herein, a cobalt-doped amorphous VS4 wrapped by reduced graphene oxide (i.e., Co0.5-VS4/rGO) is developed through a Co-induced defect engineering strategy to boost the kinetics performances. The as-prepared Co0.5-VS4/rGO demonstrates excellent rate capacities over 10 A g-1 and superior cycling stability at 5 A g-1 over 1600 cycles, which is attributed to the defects formed by Co doping, the formed amorphous structure and the robust rGO substrate. The great features of Co0.5-VS4/rGO anode are further confirmed in sodium-ion capacitors when the active carbon cathode is used. Additionally, the relationships between metal doping, the derived defects, the amorphous structure, and the sodium storage of VS4 are uncovered. This work provides deep insights into preparing amorphous functional materials and also probes the potential applications of metal sulfide-based electrode materials for advanced batteries.
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  • 文章类型: Journal Article
    建立廉价的基于固体废物的催化剂,建立过氧单硫酸盐(PMS)催化体系以降解水中卡马西平(CBZ)是一条绿色和可持续的道路。在这项研究中,制备了耐久的铜尾矿废渣基催化剂(CSWR),首次构建了高效的CSWR/PMS催化降解CBZ体系。通过碱浸和中温煅烧,CSWR的形态和结构从团块变为多孔和松散的无定形。CSWR的重建表面暴露了更多的活性位点,促进了催化反应,并将CBZ的降解速率提高了39.8倍以上。CSWR/PMS在20分钟内实现了近99.99%的CBZ去除率。特别是,形成钙钛矿型铁-钙化合物,这刺激了系统中更多HO·和SO4·-的产生。DFT计算表明,CSWR对PMS分子具有更强的吸附能和电子转移能力,提高了系统的降解效率。总的来说,这项研究提出了一种高价值废物利用的手段,为固体废物基环境功能材料的制备提供了新思路,有望在实际废水处理中得到广泛应用。
    It is a green and sustainable path to establish cheap solid waste-based catalyst to establish peroxymonosulfate (PMS) catalytic system for the degradation of carbamazepine (CBZ) in water. In this study, durable copper tailing waste residue-based catalyst (CSWR) was prepared, and efficient CSWR/PMS system was constructed for catalytic degradation of CBZ for first time. The morphology and structure of CSWR changed from clumps to porous and loose amorphous by alkali leaching and medium temperature calcination. The reconstructed surface of the CSWR exposes more active sites promotes the catalytic reaction and increases the degradation rate of CBZ by more than 39.8 times. And the CSWR/PMS achieved a CBZ removal of nearly 99.99 % in 20 min. In particular, perovskite-type iron-calcium compounds were formed, which stimulated the production of more HO• and SO4•- in the system. DFT calculation shows that CSWR has stronger adsorption energy and electron transfer ability to PMS molecules, which improved the degradation efficiency of the system. In general, this study proposed a means of high-value waste utilization, which provided a new idea for the preparation of solid waste based environmental functional materials and is expected to be widely used in practical wastewater treatment.
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  • 文章类型: Journal Article
    温和条件下金属氧化物中的阳离子交换(CE)仍然是定制其组成并实现实际应用的必要但具有挑战性的目标。在这里,我们首先开发了一种非晶化诱导策略,以实现室温CE,用于普遍合成单原子掺杂的In2O3纳米片(NSs)。密度泛函理论(DFT)计算表明,a-In2O3NS中存在的大量配位不饱和位点有助于克服CE反应的能垒。根据经验,作为主体材料的a-In2O3NS成功地与一元阳离子(Cu2+,Co2+,Mn2+,Ni2+),二元阳离子(Co2+Mn2+,Co2+Ni2+,Mn2+Ni2+),和三元阳离子(Co2+Mn2+Ni2+)。令人印象深刻的是,获得了高负载的单原子掺杂(超过10原子%)In2O3NS。此外,Cu/a-In2O3NS具有出色的乙醇产率(798.7μmolg-1h-1),对CO2光还原的选择性高达99.5%。这项工作提供了一种在温和条件下在金属氧化物中诱导CE反应的新方法,并为关键应用构建了可扩展的单原子掺杂催化剂。
    Cation exchange (CE) in metal oxides under mild conditions remains an imperative yet challenging goal to tailor their composition and enable practical applications. Herein, we first develop an amorphization-induced strategy to achieve room-temperature CE for universally synthesizing single-atom doped In2O3 nanosheets (NSs). Density functional theory (DFT) calculations elucidate that the abundant coordination-unsaturated sites present in a-In2O3 NSs are instrumental in surmounting the energy barriers of CE reactions. Empirically, a-In2O3 NSs as the host materials successfully undergo exchange with unary cations (Cu2+, Co2+, Mn2+, Ni2+), binary cations (Co2+Mn2+, Co2+Ni2+, Mn2+Ni2+), and ternary cations (Co2+Mn2+Ni2+). Impressively, high-loading single-atom doped (over 10 atom %) In2O3 NSs were obtained. Additionally, Cu/a-In2O3 NSs exhibit an excellent ethanol yield (798.7 μmol g-1 h-1) with a high selectivity of 99.5% for the CO2 photoreduction. This work offers a new approach to induce CE reactions in metal oxides under mild conditions and constructs scalable single-atom doped catalysts for critical applications.
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  • 文章类型: Journal Article
    锆基金属玻璃薄膜是纳米电子和生物医学应用的有前途的材料,但是它们在不同条件下的力学行为还没有得到很好的理解。本研究调查了射频(RF)功率和测试温度对纳米结构的影响,形态学,射频磁控溅射制备的Zr55Cu30Al10Ni5金属玻璃薄膜的蠕变行为。通过X射线衍射和显微镜对薄膜进行了表征,并通过凸起测试系统测量了它们的机械性能。结果表明,随着RF功率从75W增加到125W,薄膜呈非晶态,并表现出从非柱状到柱状的转变。柱状形态降低了抗蠕变性。杨氏模量,残余应力,和薄膜的硬度。薄膜的蠕变行为也受测试温度的影响,较高的温度导致较高的蠕变应变和较低的蠕变应力。这项研究的结果提供了有关溅射参数优化和各种应用的锆基金属玻璃薄膜设计的见解。
    Zirconium-based metallic glass films are promising materials for nanoelectronic and biomedical applications, but their mechanical behavior under different conditions is not well understood. This study investigates the effects of radio frequency (RF) power and test temperature on the nanostructure, morphology, and creep behavior of Zr55Cu30Al10Ni5 metallic glass films prepared by RF magnetron sputtering. The films were characterized by X-ray diffraction and microscopy, and their mechanical properties were measured by a bulge test system. The results show that the films were amorphous and exhibited a transition from noncolumnar to columnar morphology as the RF power increased from 75 W to 125 W. The columnar morphology reduced the creep resistance, Young\'s modulus, residual stress, and hardness of the films. The creep behavior of the films was also influenced by the test temperature, with higher temperature leading to higher creep strain and lower creep stress. The findings of this study provide insights into the optimization of the sputtering parameters and the design of zirconium-based metallic glass films for various applications.
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  • 文章类型: Journal Article
    用于酸中析氢反应(HER)的无贵金属电催化剂在基于质子交换膜的电解中起着重要作用。这里,我们开发了一种原位表面自重建策略来构建优异的酸性HER催化剂。首先,通过金属-有机骨架衍生方法,在碳布上作为预催化剂,合成了镍钨合金纳米颗粒镶嵌的自支撑钨酸锌镍纳米片。随着NiW合金纳米颗粒的溶解和阳离子的浸出,在纳米片表面原位形成非晶态镍钨氧化物(Ni-W-O)层作为实际的HER活性位点。虽然独立式结构的形态保持不变,保持活性位点的最大暴露并充当电子传输框架。因此,受益于原子的无序排列和Ni和W原子之间的协同效应,非晶Ni-W-O层表现出优异的酸性HER活性,仅具有46mV的过电位以驱动10mAcm-2的电流密度和36.4mVdec-1的相当好的Tafel斜率以及优异的耐久性。这项工作启发了在酸性溶液中HER过程中催化剂表面演化的探索,并将其用作设计酸性HER催化剂的策略。
    Noble metal free electrocatalysts for hydrogen evolution reaction (HER) in acid play an important role in proton exchange membrane-based electrolysis. Here, we develop an in situ surface self-reconstruction strategy to construct excellent acidic HER catalysts. Firstly, free-standing zinc nickel tungstate nanosheets inlaid with nickel tungsten alloy nanoparticles were synthesized on carbon cloth as pre-catalyst via metal-organic framework derived method. Amorphous nickel tungsten oxide (Ni-W-O) layer is in situ formed on surface of nanosheet as actual HER active site with the dissolution of NiW alloy nanoparticles and the leaching of cations. While the morphology of the free-standing structure remains the same, keeping the maximized exposure of active sites and serving as the electron transportation framework. As a result, benefiting from disordered arrangement of atoms and the synergistic effect between Ni and W atoms, the amorphous Ni-W-O layer exhibits an excellent acidic HER activity with only an overpotential of 46 mV to drive a current density of 10 mA cm-2 and a quite good Tafel slope of 36.4 mV dec-1 as well as an excellent durability. This work enlightens the exploration of surface evolution of catalysts during HER in acidic solution and employs it as a strategy for designing acidic HER catalysts.
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  • 文章类型: Journal Article
    电驱动的有机氧化最近显示出越来越大的潜力。然而,析氧反应(OER)是主要的竞争反应,特别是在高电流密度下,这导致产物的低法拉第效率(FE)和催化剂从电极脱离。这里,我们报道了一种负载在Ni泡沫(Ni-Cu/NF)上的双金属Ni-Cu电催化剂,以钝化OER过程,同时5-羟甲基糠醛(HMF)的氧化显着增强。在1.50V时可以实现1000mAcm-2的电流密度可逆氢电极,在很宽的电位范围内,FE和产量都保持接近100%。实验结果和理论计算均表明,Cu掺杂会阻碍OH*脱质子化为O*,从而大大钝化了OER过程。这些指导性结果为通过调节OER活性实现高效生物质升级提供了新的途径。
    Electricity-driven organo-oxidations have shown an increasing potential recently. However, oxygen evolution reaction (OER) is the primary competitive reaction, especially under high current densities, which leads to low Faradaic efficiency (FE) of the product and catalyst detachment from the electrode. Here, we report a bimetallic Ni-Cu electrocatalyst supported on Ni foam (Ni-Cu/NF) to passivate the OER process while the oxidation of 5-hydroxymethylfurfural (HMF) is significantly enhanced. A current density of 1000 mA cm-2 can be achieved at 1.50 V vs. reversible hydrogen electrode, and both FE and yield keep close to 100 % over a wide range of potentials. Both experimental results and theoretical calculations reveal that Cu doping impedes the OH* deprotonation to O* and hereby OER process is greatly passivated. Those instructive results provide a new approach to realizing highly efficient biomass upgrading by regulating the OER activity.
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