Abstract 1. Retrieving electrical energy from carbon nanotube spinning distortion (Harvestingelectrical energy from carbon nanotube tubenarntwist)
1. Harnessing electrical energy from carbon nanotube yarn twist
Many practical applications have demand for mechanical energy harvesters, including self-powered wireless sensors, structural and human health monitoring systems, and the extraction of energy from ocean waves. Kim et al. reported a carbon nanotube spinning collector that converts tensile or torsional mechanical energy into electrical energy by electrochemical conversion without the need for an external bias voltage. When the stretch crimping cycle reaches 30 Hz, it produces 250 watts of peak power per kilogram. When the weight of the yarn collector is normalized, each mechanical cycle produces up to 41.2 joules per kilogram. These energy harvesters have been used to collect wave energy in the ocean, combine heat-driven artificial muscles to convert temperature fluctuations into electrical energy, stitch into textiles for use as automatic breathing sensors, and to power LEDs and charge storage capacitors. (Science DOI: 10.1126/science.aam8771)
2. Optical imaging of surface chemistry and constrained dynamics (Optical imaging of surface chemistry and dynamics in confinement)
MaciRomero et al. performed a three-dimensional imaging of the interface structure and interface dynamics of water using a wide field second harmonic microscope with structured illumination. The second harmonic image shows the orientation of the interface water orientation caused by the charge-dipole interaction between the water molecules and the surface charge. The spatially resolved surface acid dissociation constant (pKa, s) of the silica deprotonation reaction can be determined by tracking the bending of the glass microcapillary immersed in the aqueous solution and limiting the pH-induced chemical changes on the surface. Due to surface heterogeneity, this value is between 2.3 and 10.7 along the wall of a single capillary. Finally, they also imaged water molecules that rotate along the oscillating external electric field. (Science DOI: 10.1126/science.aal4346)
3. Two-dimensional heterostructure, multiple heterostructures, and robust growth of the superlattice (Robust epitaxial growth of two-dimensional heterostructures, multiheterostructures, and superlattices)
Zhang et al. reported a general synthetic strategy for robust growth of two-dimensional (2D) atomic crystals with different lateral heterostructures, multiple heterostructures, and superlattices. The reverse flow during the temperature swing phase during sequential vapor deposition growth enables the cooling of existing 2D crystals to prevent undesired thermal degradation and uncontrolled uniform nucleation, thereby achieving very robust block-by-block epitaxial growth. Raman and photoluminescence mapping studies have shown that a wide range of two-dimensional heterostructures (such as WS2-WSe2 and WS2-MoSe2), multiple heterostructures (such as WS2-WSe2-MoS2 and WS2-MoSe2-WSe2) and superlattices ( Such as WS2-WSe2-WS2-WSe2-WS2) can be easily made by precisely controlled spatial modulation. Transmission electron microscopy studies revealed clear chemical modulation with a distinct atomic interface. Electrical transport studies of the WSE2-WS2 lateral junctions show diode characteristics with a rectification ratio of 105. (Science DOI: 10.1126/science.aan6814)
4. Ruthenium catalyzed insertion of adjacent diol carbon atoms into CC bonds: Entry to type II polyketides
The current catalytic processes involving carbon-carbon bond activation rely on π-unsaturated conjugates. Using the concept of transfer hydrogen coupling, Bender et al. reported that benzocyclobutenone can be modified by ruthenium (O)-catalyzed cycloaddition to modify two adjacent saturated diol carbon-hydrogen bonds. These regions and diastereoselective methods make it possible to polymerize a type II polyketide substructure. (Science DOI: 10.1126/science.aao0453)
5. The use of sub-nanocarbon nanotube pores to achieve enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins
Rapid water transport methods using carbon nanotube pores increase the likelihood of using carbon nanotubes in next-generation water treatment technologies. Tunuguntla et al. restricted water to a single longitudinal chain by passing water through 0.8 nm diameter carbon nanotube porin (CNTPs), which is an order of magnitude greater than that of a biological water transporter and a relatively wide CNT pore. The intermolecular hydrogen bond rearrangement required to enter the nanotubes determines the energy barrier and can be manipulated to increase the water delivery rate. CNTPs block anion transport, so even at salinities above seawater levels, they can be configured as switchable ion diodes to adjust their ion selectivity. These properties make CNTPs a promising material for the development of membrane separation technology. (Science DOI: 10.1126/science.aan2438)
6. Epitix of advanced nanowire quantum devices
Semiconductor nanowires are ideal for implementing a variety of low-dimensional quantum devices. In particular, when a semiconductor nanowire having a strong spin-orbit coupling is in contact with a superconductor, a topological phase of matter having a non-Abelian quasiparticle (for example, an arbitrary sub-particle) may occur. In order to fully exploit the potential of non-Abelian arbitrary children, which are key elements of topological quantum computing, they need to be exchanged in well-controlled weaving operations. The basic hardware used for weaving is a crystalline nanowire network coupled to a superconducting island. Gazibegovic et al. show a technique for synthesizing complex quantum devices from the bottom up, with particular attention to nanowire networks having a predetermined number of superconducting islands. Structural analysis confirmed the high crystalline quality of the nanowire junction and the epitaxial superconductor-semiconductor interface. The measurement of quantum transport as a nanowire "tag" exhibits the Aharonov-Bohm effect and the weak anti-localization effect, indicating a phase coherent system with strong spin-orbit coupling. In addition, a strong superconducting energy gap with near-induction (disappearance of sub-gap conductance) was exhibited in these hybrid superconductor-semiconductor nanowires, indicating the successful development of materials required for the first weaving experiment. This approach opens up new avenues for the three-dimensional quantum structure epitaxy that has the potential to become a key component of various quantum devices. (Nature DOI: 10.1038/nature23468)
7. Nanodiffusion in electrocatalytic films
Electrochemical reaction catalysis associated with modern energy challenges has led to widespread research interest, and films deposited on electrodes are generally more prone to in-phase catalysis. Depending on the effectiveness and selectivity, the potential diversification of such films can be achieved by spraying catalytic nanoparticles onto a conductive network. In combination with this catalytic reaction, Costentin et al. theoretically analyzed various modes of substrate diffusion (diffusion toward nanoparticles and linear diffusion of film and linear diffusion of solution). By a dimensionless parameter containing all experimental factors, the corresponding conditions for nano-diffusion dominated mass transfer mode can be selected. These theories are experimentally verified by a Pt/C mixture dispersed on a Nafion film. The theory was tested as the experimental variable density and scan rate of the nanoparticles. (Nature Materials DOI: 10.1126/science.aan0202)
8. Theoretically guided discovery of thermoelectric materials
The development potential of thermoelectric materials is huge, so the development potential of solid-state refrigeration and power generation is also huge. The progress made so far has been limited by the breadth and diversity of chemical space and the continuity of experimental work. Gorai et al. reviewed and discussed the following: how recent computational advances have changed researchers' ability to predict electron and phonon transport and scattering and material doping, and investigated the effectiveness of research to calculate critical transport properties in large chemical spaces. method. These high-throughput methods combined with experimental feedback can facilitate the discovery of new types of thermoelectric materials. In a smaller subset of materials, calculations can guide optimal chemical and structural adjustments to improve material performance and provide insight into potential transport physics. In addition to complete materials, calculations can also be used to rationalize structural and chemical modifications (such as defects, interfaces, dopants, and alloys) to optimize the performance of the transport performance. Computational predictions of material search and design are becoming a new model for exploring thermoelectric materials. (Nature Reviews Materials DOI: 10.1038/natrevmats.2017.53)
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