Ultrahigh Energy Absorption Multifunctional Spinodal NanoarchitecturesGuell Izard, Anna; Bauer, Jens; Crook, Cameron; Turlo, Vladyslav; Valdevit, Lorenzo
doi: 10.1002/smll.201903834pmid: 31531942
Nanolattices are promoted as next‐generation multifunctional high‐performance materials, but their mechanical response is limited to extreme strength yet brittleness, or extreme deformability but low strength and stiffness. Ideal impact protection systems require high‐stress plateaus over long deformation ranges to maximize energy absorption. Here, glassy carbon nanospinodals, i.e., nanoarchitectures with spinodal shell topology, combining ultrahigh energy absorption and exceptional strength and stiffness at low weight are presented. Noncatastrophic deformation up to 80% strain, and energy absorption up to one order of magnitude higher than for other nano‐, micro‐, macro‐architectures and solids, and state‐of‐the‐art impact protection structures are shown. At the same time, the strength and stiffness are on par with the most advanced yet brittle nanolattices, demonstrating true multifunctionality. Finite element simulations show that optimized shell thickness‐to‐curvature‐radius ratios suppress catastrophic failure by impeding propagation of dangerously oriented cracks. In contrast to most micro‐ and nano‐architected materials, spinodal architectures may be easily manufacturable on an industrial scale, and may become the next generation of superior cellular materials for structural applications.
Hydrothermal Coating of Patterned Carbon Nanotube Forest for Structured Lithium‐Ion Battery ElectrodesJessl, Sarah; Copic, Davor; Engelke, Simon; Ahmad, Shahab; De Volder, Michael
doi: 10.1002/smll.201901201pmid: 31544336
Controlling the arrangement and interface of nanoparticles is essential to achieve good transfer of charge, heat, or mechanical load. This is particularly challenging in systems requiring hybrid nanoparticle mixtures such as combinations of organic and inorganic materials. This work presents a process to coat vertically aligned carbon nanotube (CNT) forests with metal oxide nanoparticles using microwave‐assisted hydrothermal synthesis. Hydrothermal processes normally damage delicate CNT forests, which is addressed here by a combination of lithographic patterning, transfer printing, and reduction of the synthesis time. This process is applied for the fabrication of structured Li‐ion battery (LIB) electrodes where the aligned CNTs provide a straight electron transport path through the electrode and the hydrothermal coating process is used to coat the CNTs with conversion anode materials for LIBs. These nanoparticles are anchored on the surface of the CNTs and batteries fabricated following this process show a fourfold longer cyclability. Finally, this process is used to create thick electrodes (350 µm) with a gravimetric capacity of over 900 mAh g−1.
Solvent‐Exchange Strategy toward Aqueous Dispersible MoS2 Nanosheets and Their Nitrogen‐Rich Carbon Sphere Nanocomposites for Efficient Lithium/Sodium Ion StorageWang, Yufeng; Wang, Kai; Zhang, Chao; Zhu, Jixin; Xu, Jingsan; Liu, Tianxi
doi: 10.1002/smll.201903816pmid: 31532922
Major challenges in developing 2D transition‐metal disulfides (TMDs) as anode materials for lithium/sodium ion batteries (LIBs/SIBs) lie in rational design and targeted synthesis of TMD‐based nanocomposite structures with precisely controlled ion and electron transport. Herein, a general and scalable solvent‐exchange strategy is presented for uniform dispersion of few‐layer MoS2 (f‐MoS2) from high‐boiling‐point solvents (N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethyl formaldehyde (DMF), etc.) into low‐boiling‐point solvents (water, ethanol, etc.). The solvent‐exchange strategy dramatically simplifies high‐yield production of dispersible MoS2 nanosheets as well as facilitates subsequent decoration of MoS2 for various applications. As a demonstration, MoS2‐decorated nitrogen‐rich carbon spheres (MoS2‐NCS) are prepared via in situ growth of polypyrrole and subsequent pyrolysis. Benefiting from its ultrathin feature, largely exposed active surface, highly conductive framework and excellent structural integrity, the 2D core–shell architecture of MoS2‐NCS exhibits an outstanding reversible capacity and excellent cycling performance, achieving high initial discharge capacity of 1087.5 and 508.6 mA h g−1 at 0.1 A g−1, capacity retentions of 95.6% and 94.2% after 500 and 250 charge/discharge cycles at 1 A g−1, for lithium/sodium ion storages, respectively.
Remote Light‐Responsive Nanocarriers for Controlled Drug Delivery: Advances and PerspectivesZhao, Wei; Zhao, Yongmei; Wang, Qingfu; Liu, Tianqing; Sun, Jingjiang; Zhang, Run
doi: 10.1002/smll.201903060pmid: 31599125
Engineering of smart photoactivated nanomaterials for targeted drug delivery systems (DDS) has recently attracted considerable research interest as light enables precise and accurate controlled release of drug molecules in specific diseased cells and/or tissues in a highly spatial and temporal manner. In general, the development of appropriate light‐triggered DDS relies on processes of photolysis, photoisomerization, photo‐cross‐linking/un‐cross‐linking, and photoreduction, which are normally sensitive to ultraviolet (UV) or visible (Vis) light irradiation. Considering the issues of poor tissue penetration and high phototoxicity of these high‐energy photons of UV/Vis light, recently nanocarriers have been developed based on light‐response to low‐energy photon irradiation, in particular for the light wavelengths located in the near infrared (NIR) range. NIR light‐triggered drug release systems are normally achieved by using two‐photon absorption and photon upconversion processes. Herein, recent advances of light‐responsive nanoplatforms for controlled drug release are reviewed, covering the mechanism of light responsive small molecules and polymers, UV and Vis light responsive nanocarriers, and NIR light responsive nanocarriers. NIR‐light triggered drug delivery by two‐photon excitation and upconversion luminescence strategies is also included. In addition, the challenges and future perspectives for the development of light triggered DDS are highlighted.
Ultrahigh Rate Performance of Hollow Antimony Nanoparticles Impregnated in Open Carbon Boxes for Sodium‐Ion Battery under Elevated TemperatureXu, Anding; Xia, Qi; Zhang, Shenkui; Duan, Huanhuan; Yan, Yurong; Wu, Songping
doi: 10.1002/smll.201903521pmid: 31532895
Antimony is a competitive and promising anode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, the poor rate capability and fast capacity fading greatly restrict its practical application. To address the above issues, a facile and eco‐friendly sacrificial template method is developed to synthesize hollow Sb nanoparticles impregnated in open carbon boxes (Sb HPs@OCB). The as‐obtained Sb HPs@OCB composite exhibits excellent sodium storage properties even when operated at an elevated temperature of 50 °C, delivering a robust rate capability of 345 mAh g−1 at 16 A g−1 and rendering an outstanding reversible capacity of 187 mAh g−1 at a high rate of 10 A g−1 after 300 cycles. Such superior electrochemical performance of the Sb HPs@OCB can be attributed to the comprehensive characteristics of improved kinetics derived from hollow Sb nanoparticles impregnated into 2D carbon nanowalls, the existence of robust SbOC bond, and enhanced pseudocapacitive behavior. All those factors enable Sb HPs@OCB great potential and distinct merit for large‐scale energy storage of SIBs.
Periodic Operation of a Dynamic DNA Origami Structure Utilizing the Hydrophilic–Hydrophobic Phase‐Transition of Stimulus‐Sensitive PolypeptidesGoetzfried, Marisa A.; Vogele, Kilian; Mückl, Andrea; Kaiser, Marcus; Holland, Nolan B.; Simmel, Friedrich C.; Pirzer, Tobias
doi: 10.1002/smll.201903541pmid: 31531953
Dynamic DNA nanodevices are designed to perform structure‐encoded motion actuated by a variety of different physicochemical stimuli. In this context, hybrid devices utilizing other components than DNA have the potential to considerably expand the library of functionalities. Here, the reversible reconfiguration of a DNA origami structure using the stimulus sensitivity of elastin‐like polypeptides is reported. To this end, a rectangular sheet made using the DNA origami technique is functionalized with these peptides and by applying changes in salt concentration the hydrophilic–hydrophobic phase transition of these peptides actuate the folding of the structure. The on‐demand and reversible switching of the rectangle is driven by externally imposed temperature oscillations and appears at specific transition temperatures. Using transmission electron microscopy, it is shown that the structure exhibits distinct conformational states with different occupation probabilities, which are dependent on structure‐intrinsic parameters such as the local number and the arrangement of the peptides on the rectangle. It is also shown through ensemble fluorescence resonance energy transfer spectroscopy that the transition temperature and thus the thermodynamics of the rectangle‐peptide system depends on the stimuli salt concentration and temperature, as well as on the intrinsic parameters.