A general approach toward extremely stretchable and highly conductive electrodes was developed. The method involves wrapping a continuous carbon nanotube (CNT) thin film around pre‐stretched elastic wires, from which...
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A general approach toward extremely stretchable and highly conductive electrodes was developed. The method involves wrapping a continuous carbon nanotube (CNT) thin film around pre‐stretched elastic wires, from which high‐performance, stretchable wire‐shaped supercapacitors were fabricated. The supercapacitors were made by twisting two such CNT‐wrapped elastic wires, pre‐coated with poly(vinyl alcohol)/H 3 PO 4 hydrogel, as the electrolyte and separator. The resultant wire‐shaped supercapacitors exhibited an extremely high elasticity of up to 350 % strain with a high device capacitance up to 30.7 F g −1 , which is two times that of the state‐of‐the‐art stretchable supercapacitor under only 100 % strain. The wire‐shaped structure facilitated the integration of multiple supercapacitors into a single wire device to meet specific energy and power needs for various potential applications. These supercapacitors can be repeatedly stretched from 0 to 200 % strain for hundreds of cycles with no change in performance, thus outperforming all the reported state‐of‐the‐art stretchable electronics.
Branched nanowire (NW) heterostructures have recently been attracted considerable attention for solar water splitting and clean hydrogen production due to their unique properties such as nanoscale integration of diffe...
Branched nanowire (NW) heterostructures have recently been attracted considerable attention for solar water splitting and clean hydrogen production due to their unique properties such as nanoscale integration of different functional materials, greatly enhanced junction and surface area, enhanced gas evolution efficiency, broadband light absorption, etc. Moreover, branched NWs can be fabricated using facile and scalable fabrication methods such as hydrothermal or solvothermal growth methods. In this presentation, we show branched NWs of different compositions for core (or trunk) and branch NWs which were fabricated with facile and low-cost synthesis methods using cheap, non-toxic, and earth abundant materials including Si, CuO, Cu2O, ZnO, TiO2, and Fe2O3. The branched NW structures and the heterostructures' interfaces are investigated in detail using different characterization techniques such as SEM/HRSEM, TEM/HRTEM, STEM/HRSETM, etc. The photoelectrochemical (PEC) performances including photocurrent turn-on potential, photocurrent, solar conversion efficiency, and incident photon-to-current efficiency (IPCE) are studied systematically and optimized, based on different core and branch NW dimensions, for each specific branched NW heterostructure to provide efficient water splitting in a neutral medium. The electrode stability of different branched NWs is also investigated and long-term stability of over one day or several hours using a thin passivation layer or robust branched NWs are presented. The achieved results pave the way for accomplishing spontaneous overall solar water splitting for clean, efficient, cost-effective and durable solar hydrogen generation at large scales.
We study the equilibrium and nonequilibrium properties of Boolean decision problems with competing interactions on scale-free networks in an external bias (magnetic field). Previous studies at zero field have shown a ...
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We study the equilibrium and nonequilibrium properties of Boolean decision problems with competing interactions on scale-free networks in an external bias (magnetic field). Previous studies at zero field have shown a remarkable equilibrium stability of Boolean variables (Ising spins) with competing interactions (spin glasses) on scale-free networks. When the exponent that describes the power-law decay of the connectivity of the network is strictly larger than 3, the system undergoes a spin-glass transition. However, when the exponent is equal to or less than 3, the glass phase is stable for all temperatures. First, we perform finite-temperature Monte Carlo simulations in a field to test the robustness of the spin-glass phase and show that the system has a spin-glass phase in a field, i.e., exhibits a de Almeida-Thouless line. Furthermore, we study avalanche distributions when the system is driven by a field at zero temperature to test if the system displays self-organized criticality. Numerical results suggest that avalanches (damage) can spread across the whole system with nonzero probability when the decay exponent of the interaction degree is less than or equal to 2, i.e., that Boolean decision problems on scale-free networks with competing interactions can be fragile when not in thermal equilibrium.
We report measurements of electrical resistivity, magnetic susceptibility, specific heat, and thermoelectric power on the system Pr1−xCexPt4Ge12. Superconductivity is suppressed with increasing Ce concentration up to ...
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We report measurements of electrical resistivity, magnetic susceptibility, specific heat, and thermoelectric power on the system Pr1−xCexPt4Ge12. Superconductivity is suppressed with increasing Ce concentration up to x=0.5, above which there is no evidence for superconductivity down to 1.1 K. The Sommerfeld coefficient γ increases with increasing x from ∼48 mJ/mol K2 up to ∼120 mJ/mol K2 at x= 0.5, indicating an increase in strength of electronic correlations. The temperature dependence of the specific heat at low temperatures evolves from roughly T3 for x= 0 to e−Δ/T behavior for x= 0.05 and above, suggesting a crossover from a nodal to a nodeless superconducting energy gap or a transition from multiband to single-band superconductivity. Fermi-liquid behavior is observed throughout the series in low-temperature magnetization, specific heat, and electrical resistivity measurements.
An all‐solid‐state, lightweight, flexible, and wearable polymer solar cell (PSC) textile with reasonable photovoltaic performance has been developed. A metal textile electrode made from micrometer‐sized metal wires...
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An all‐solid‐state, lightweight, flexible, and wearable polymer solar cell (PSC) textile with reasonable photovoltaic performance has been developed. A metal textile electrode made from micrometer‐sized metal wires is used as the cathode, and the surfaces of the metal wires are dip‐coated with the photoactive layers. Two ultrathin, transparent, and aligned carbon nanotube sheets that exhibit remarkable electronic and mechanical properties were coated onto the modified metal textile at both sides as the anode to produce the desired PSC textile. Because of the designed sandwich structure, the PSC textile displays the same energy conversion efficiencies regardless of which side it is irradiated from. As expected, the PSC textiles are highly flexible, and their energy conversion efficiencies varied by less than 3 % after bending for more than 200 cycles. The PSC textile shows an areal density (5.9 mg cm −2 ) that is lower than that of flexible film‐based PSCs (31.3 mg cm −2 ).
A wire‐shaped energy device that can perform photoelectric conversion and electrochemical storage was developed through a simple but effective twisting process. The energy wire exhibited a high energy conversion effi...
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A wire‐shaped energy device that can perform photoelectric conversion and electrochemical storage was developed through a simple but effective twisting process. The energy wire exhibited a high energy conversion efficiency of 6.58 % and specific capacitance of 85.03 μF cm −1 or 2.13 mF cm −2 , and the two functions were alternately realized without sacrificing either performance.
Perovskite solar cells have triggered a rapid development of new photovoltaic devices because of high energy conversion efficiencies and their all‐solid‐state structures. To this end, they are particularly useful fo...
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Perovskite solar cells have triggered a rapid development of new photovoltaic devices because of high energy conversion efficiencies and their all‐solid‐state structures. To this end, they are particularly useful for various wearable and portable electronic devices. Perovskite solar cells with a flexible fiber structure were now prepared for the first time by continuously winding an aligned multiwalled carbon nanotube sheet electrode onto a fiber electrode; photoactive perovskite materials were incorporated in between them through a solution process. The fiber‐shaped perovskite solar cell exhibits an energy conversion efficiency of 3.3 %, which remained stable on bending. The perovskite solar cell fibers may be woven into electronic textiles for large‐scale application by well‐developed textile technologies.
Polymer dispersed liquid crystals are a useful model system for studying the relationship between surface topology and defect structures. They are comprised of a polymer matrix with suspended spherical nematic drops a...
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Polymer dispersed liquid crystals are a useful model system for studying the relationship between surface topology and defect structures. They are comprised of a polymer matrix with suspended spherical nematic drops and are topologically constrained to host defects of an elementary hedgehog charge per droplet, such as bulk or surface point defects or closed disclination loops. We control the genus of the closed surfaces confining such micrometer-sized nematic drops with tangential boundary conditions for molecular alignment imposed by the polymer matrix, allowing us to avoid defects or, on the contrary, to generate them in a controlled way. We show, both experimentally and through numerical modeling, that topological constraints in nematic microdrops can be satisfied by hosting topologically stable half-integer bulk defect lines anchored to opposite sides of handlebody surfaces. This enriches the interplay of topologies of closed surfaces and fields with nonpolar symmetry, yielding new unexpected configurations that cannot be realized in vector fields, having potential implications for topologically similar defects in cosmology and other fields.
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