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High thermoelectric figure of merit ZT of 1.5 and a high average ZT >1.0 between 300 and 850 K can be achieved for Yb-filled CoSb3, which are superior to those of any single-element-filled skutterudite and comparable to the best in this class of materials. The long-term debate about the Yb-filling fraction limit in CoSb3 is clarified to be ~0.29, and the excess Yb mainly forms metallic YbSb2 precipitates. The transport properties of the x >0.35 samples with YbSb2 precipitates are quantitatively reproduced by the Bergman’s composite theory, providing new understanding of the role of Yb in CoSb3.
The application of a conjugated polymer with 9,10-di(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (exTTF) units as cathode and zinc as anode enables an aqueous-based hybrid organic battery. This energy storage device features ultra-high rate performance of up to a full charge in 30 s and an extended lifetime up to 10 000 cycles.
A new type of non-noble-metal hydrogen evolution reaction (HER) electrocatalyst based on ultrafine Mo2C nanoparticles embedded within 3D N-doped carbon nanofiber networks was fabricated by using a cheap, green, 3D nanostructured biomass (bacterial cellulose) as precursor. It exhibits remarkable electrocatalytic HER performance from pH 0 to pH 14.
We report the synthesis of ruthenium nanocrystal-decorated vertically aligned graphene nanosheets grown on nickel foam. As an effective binder-free cathode for Li-O2 batteries, it can significantly reduce the charge overpotential via their effects on the oxygen evolution reaction and achieve high specific capacity, leading to an enhanced electrochemical performance.
A novel and effective crystalline-Si/amorphous-Si core/shell sample configuration has been devised. The malleable amorphous Si shell helped inhibit brittle fracture, provide the confinement to significantly raise the stress level, and extend the plastic flow in crystalline Si core. This enabled a real-time observation of the stress-induced crystalline-to-amorphous transition (CAT) process in Si. In situ TEM compression experiment demonstrated a direct amorphization process from the single crystalline diamond cubic Si phase, owing to the accumulation of plastic strain and profuse stacking faults. Deep insights of the CAT process have been achieved from density functional theory simulations.
Nickel doped Li3VO4 nanocrystallites with high surface energy showed excellent lithium ion storage property with a capacity of 650 mAh g−1 at 50 mAh g−1 and excellent capacity stability as anode in lithium ion batteries. The nickel doping promoted the formation of V4+ and more amorphous in the surface of Li3VO4, probably resulting in higher surface energy, more nucleation sites for the phase transformation and reducing the activation energy of the redox reactions and phase transition during the Li+ intercalation/extraction processes.
Herein, we fabricated pure poly(3-hexylthiophene) (P3HT) film with highly oriented morphology using a small-molecule 1,3,5-trichlorobenzene (TCB) as the template for polymer epitaxy with a temperature gradient crystallization process. The strong π–π conjugated interactions as well as the very close matching between the repeat distance of the thiophene units in P3HT and the repeat distance of TCB molecules have successfully induced the epitaxy process, allowing the P3HT polymer chains to lock onto the lattice of TCB, forming highly ordered P3HT chains in the direction parallel to the fiber axis. As a result, the electrical conductivity in the direction parallel to the fiber axis was significantly improved. The maximum thermoelectric power factor and ZT value at 365 K reached 62.4 μW mK-2 and 0.1 in the parallel direction of the TCB-treated P3HT film.
Peculiar GaN/InGaN-based high-density nanocrystal array was demonstrated by a simple self-assembly process. The nanocrystals consist of bending InGaN nanoplates and supporting GaN nanocolumns. The nanocrystals are umbrella shaped with diameters of ∼200–700 nm; therefore, they are referred to as InGaN nanoumbrellas. An extremely wide range of photoluminescence was obtained from a small excitation diameter of ∼10 μm of the array. The result indicates that the high-density GaN/InGaN-based nanoumbrella array can be used as a source of white light without phosphors.
A new hybrid, fabricated by incorporating molybdenum carbide (Mo2C) nanoparticles into nitrogen-implanted three-dimensional carbon matrix (MoCN-3D), has been developed as a highly active and durable nonprecious metal electrocatalyst for HER. The porous architecture of the developed catalyst MoCN-3D can provide continuous mass transportation with a minimal diffusion resistance and thus produce effective electrocatalytic kinetics in both acidic and alkaline media.
We have rationally synthesized a binder-free and robust electrode by directly growing urchin-shaped α-MnO2 nanostructures on porous reduced graphene oxide-coated carbon microfiber (MGC) mats and fabricated an aqueous sodium–air cell using the MGC as an air electrode to demonstrate the rechargeability of an aqueous sodium–air battery. The fabricated aqueous Na–air cell exhibited excellent rechargeability, rate capability and round-trip efficiency.
