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Ultralow thermal conductivity and improved ZT of CuInTe2 by high-entropy structure design
No full textEntropy engineering has been widely applied to thermoelectrics as an effective strategy to reduce thermal conductivity. On the other hand,the increase of configuration entropy certainly decreases the electrical conductivity simultaneously, leading to the worsening of the thermoelectric performance. In this paper, we report a study on the high entropy structure design for chalcogenide CuInTe2. Based on the analysis of electronic band structure, we show how to optimize the constituents of high-entropy compound to relieve the influence on electrical conductivity. Compared with (CuAg)(0.5)(ZnGeGaIn)(0.25)Te-2, which has the highest configuration entropy among our samples, the optimized constituents of Cu0.8Ag0.2(ZnGe)(0.1)(GaIn)(0.4)Te-2 shows the one order higher carrier mobility and little bit higher thermal conductivity. Finally, the highest ZT of 1.02 at 820 K is obtained in Cu0.8Ag0.2(ZnGe)(0.1)(GaIn)(0.4)Te-2, accompanying with a very low thermal conductivity of 0.5 Wm(-1)K(-1). This work provides a successful example of the high-entropy structure design for thermoelectrics, and it indicates that to reconcile the different requirements of thermal conductivity and electrical conductivity is crucial. (C) 2021 Elsevier Ltd. All rights reserved
In Situ Nitrogen Retention of Carbon Anode for Enhancing the Electrochemical Performance for Sodium-Ion Battery
No full textRetaining nitrogen for polyacrylonitrile (PAN) based carbon anode is a cost-effective way to make full use of the advantages of PAN for sodium-ion batteries (SIBs). Here, a simple strategy has been successfully adopted to retain N atoms in situ and increase production yield of a novel composite PAZ by mixing 3 wt % of zinc borate (ZB) with poly (acrylonitrile-co-itaconic acid) (PANIA). Among the prepared carbonised fibre (CF) samples, PAZ-CF-700 maintains the highest N content, retaining 90 % of the original N from PANIA. It represents the highest capacity storage contribution (80.55 %) and the lowest impedance R-ct (117 omega). Consequently, the specific capacity increases from 60 mAh g(-1) of PANIA-CF-700 to 190 mAh g(-1) of PAZ-CF-700 at a current density of 100 mA g(-1). At the same time, PAZ-CF-700 exhibits a good rate performance and excellent long-term cycling stability with a specific capacity of 94 mAh g(-1) after 4000 cycles at 1.6 A g(-1)
High-Throughput Screening of a Single-Atom Alloy for Electroreduction of Dinitrogen to Ammonia
No full textExploring electrocatalysts with high activity, selectivity, and stability is essential for the development of applicable electrocatalytic ammonia synthesis technology. By performing density functional theory calculations, we systematically investigated the potential of a series of transition-metal-doped Au-based single-atom alloys (SAAs) as promising electrocatalysts for nitrogen reduction reaction (NRR). The overall process for the Au-based electrocatalyst suffers from the limiting potential arising from the first hydrogenation step of the reduction of *N-2 to *NNH. However, SAAs showed to be favorable toward lowering free energy barriers by increasing the binding strength of N-2. According to simulation results, three descriptors were proposed to describe the first hydrogenation step Delta G(*N-2 -> *NNH): Delta G(*NNH), d-band center, and d/root E-m. Eight doped elements (Ti, V, Nb, Ru, Ta, Os, W, and Mo) were initially screened out with a limiting potential ranging from -0.75 to -0.30 V. Particularly, Mo- and W-doped systems possess the best activity with a limiting potential of -0.30 V each. Then, the intrinsic relationship between the structure and potential performance was analyzed using machine learning. The selectivity, feasibility, and stability of these candidates were also evaluated, confirming that SAA containing Mo, Ru, Ta, and W could be outstanding NRR electrocatalysts. This work not only broadens our understanding of SAA application in electrocatalysis, but also leads to the discovery of novel NRR electrocatalysts
Hydrogen Bonding in Self-Healing Elastomers
No full textIn the past decade, the self-healing elastomers based on multiple hydrogen bonding have attracted ample attention due to their rich chemical structures, adjustable mechanical properties, fast healing speed, and high healing efficiency. Through prolonging the service life and fast recovery of the mechanical properties, self-healing elastomers can be potentially applied in the field of wearable electronics, electronic skins, motion tracking, and health monitoring. In this perspective, we will introduce the concept and classification of self-healing materials first, then the hydrogen bonds, and the corresponding position of hydrogen-bonding units in the polymer structures. We will also conclude the potential application of hydrogen bonding-based elastomers. Finally, a summary and outlook will be provided
Efficient monolithic diamond Raman yellow laser at 572.5 nm
No full textA high-power Raman yellow laser with a wavelength of 572.5 nm is demonstrated. High-power Raman laser is always restricted by various thermal effects inside the Raman crystals. Based on the theoretical analyze about the thermal effects, the internal heat accumulation can be slightly adjusted by output transmittances. Yellow laser is achieved with the average output power of 9.2 W and the slope efficiency of 60.8%, used a monolithic diamond crystal, with high thermal conductivity, as the Raman medium. The corresponding results have impacts on promoting the application of yellow laser into the fields of medical treatment, laser display, and scientific investigation
Electric Field Control of Magnetic Properties by Means of Li+ Migration in FeRh Thin Film
No full textRecently, the electric control of magnetism by means of ion migration has been proven to be effective with nonvolatility and low energy consumption. In this work, we investigated the control of the magnetic properties of FeRh films by means of Li+ migration in FeRh/MgO heterostructures. We found that the migration of Li+ could reduce the phase transition temperature by 2 K with an applied voltage of 1 V. Meanwhile, the voltage-dependent saturated magnetization exhibited a repetitive switching behavior from high to low magnetization values while the voltage was switched from 4 to -4 V, indicating that the migration of Li+ in the FeRh film can be reversible. This provides a means to control the magnetic properties of FeRh films
Scalable and facile synthesis of acetal covalent adaptable networks with readily adjustable properties
No full textCovalent adaptable networks (CANs) were rapidly developed to address the recycle issue of thermosets; however, facile and scalable synthesis of CANs is still a challenge. Here, we report the preparation of the acetal-based CANs with commercially available raw materials by a one-pot method without solvent, which can achieve zero atom loss over the whole process. The CANs were synthesized through a radical copolymerization of styrene (or 2-ethylhexyl methacrylate) and 2-hydroxyethyl methacrylate and an addition reaction of the hydroxyl from 2-hydroxyethyl methacrylate and a divinyl ether in one pot. The CANs could be recycled by hot-press reprocessing, and could also be degraded and regenerated into networks to achieve closed-loop recycling. In addition, the thermal and mechanical properties could be readily regulated by changing the monomers for the preparation. This work provides a scalable method to prepare acetal-based CANs, which will shorten the scientific research of CANs to industrialization
Efficient photocatalytic hydrogen evolution over carbon supported antiperovskite cobalt zinc nitride
No full textPhotocatalytic solar to chemical energy conversion is an important energy conversion process but suffer from low efficiency. Thus, development of efficient photocatalytic system using earth-abundant elements with low costs is highly desirable. Here, antiperovskite cobalt zinc nitride has been synthesized and coupled with carbon black (Co3ZnN/C) for visible light driven hydrogen production in an Eosin Y-sensitized system. Replacement of cobalt atom by zinc atom leads to an improved charge transfer kinetics and catalytic properties compared with Co4N. Density functional theory (DFT) calculations further reveal the adjusted electronic structure of Co3ZnN by zinc atom introducing. The lower antibonding energy states of Co3ZnN are beneficial for the hydrogen desorption. Moreover, carbon black as support effectively reduces the particle size of Co3ZnN and benefits to the electron storage and adsorption capabilities. The optimal Co3ZnN/C catalysts exhibit the H-2 evolution rate of 15.4 mu mol mg(-1) h(-1),which is over 6 times higher than that of monometallic Co4N. It is even greater than those of most of Eosin Y-sensitized systems
Electrochemical properties promotion of CrSiN coatings in seawater via Ni incorporation
No full textNickel was incorporated into CrSiN coatings to improve their electrochemical properties. The incorporated Ni existed as elementary substance (zero valence) regardless of concentration (5.2-13.9 at %). Ni-CrSiN coatings with a thickness around 2.5 mm all presented the nano-composite structure composing of CrN crystal, amorphous nickel and amorphous SiNx. With increasing Ni content, the morphology of Ni-CrSiN coatings became compact. The electrochemical impedance spectrum results showed that the charge transfer resistance (R-ct) of Ni-CrSiN coatings increased from 1.62 x 10(6) to 3.51 x 10(6) Omega cm(2) as Ni concentration increased from 0 to 8.3 at %. Meantime, the corrosion current density (i(corr)) decreased to 18.54 nA/cm(2) owing to the extra formation of nickel oxides. In contrast, icorr increased to 31.83 nA/cm(2) at Ni concentration of 13.9 at % due to the premature pitting of passive layer. (C) 2020 Elsevier B.V. All rights reserved