Surface engineering,which modulates the electronic structure and adsorption/desorption properties of electrocatalysts,is one of the key strategies for improving the catalytic ***,we demonstrate a facile solid-phase re...
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Surface engineering,which modulates the electronic structure and adsorption/desorption properties of electrocatalysts,is one of the key strategies for improving the catalytic ***,we demonstrate a facile solid-phase reaction for surface engineering of MnO_(2)to boost the oxygen reduction *** reaction with surface hydroxy groups,La single atoms with loading amount up to 2.7 wt%are anchored onto a-MnO_(2)*** surface engineering,the oxygen reduction reaction(ORR)kinetics is significantly improved with the half-wave potential from 0.70 to 0.84 V,the number of transferred electrons from 2.5 to 3.9 and the limiting current density from 4.8 to 6.0 mA·cm^(-2).In addition,the catalyst delivers superior discharge performance in both alkaline and neutral metal–air *** functional theory(DFT)calculations reveal that atomic La modulates the surface electronic configuration of MnO_(2),reduces its d-band center and thus lowers the OOH*and O*reaction energy *** work provides a new route for rational design of highly active electrocatalyst and holds great potential for application in various catalytic reactions.
MgZn_(2)-type(Hf,Ta)Fe_(2),known for its negative thermal expansion during magnetic transition,is a key component in the production of zero thermal expansion *** paper presents a basic approach for designing such comp...
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MgZn_(2)-type(Hf,Ta)Fe_(2),known for its negative thermal expansion during magnetic transition,is a key component in the production of zero thermal expansion *** paper presents a basic approach for designing such composites by introducing an additional Laves phase through atomic ***,Co,Ni,A1 and V were chosen to substitute Fe in(Hf,Ta)Fe_(2).The addition of Co or Ni results in the creation of an extra MgCu_(2)(C15)phase in the MgZn_(2)(C14)*** C15phase exhibits positive thermal expansion,which effectively compensates for the negative thermal expansion of the C14 *** adjusting the amount of Co or Ni,zero thermal expansion can be achieved in a given temperature ***,the replacement of Fe by Al or V yields another C14 phase with a higher doping element content relative to the C14 *** two C14 phases possess different magnetic transition temperatures and negative thermal expansion temperature *** combination of the two C14 phases results in zero thermal expansion due to the effective thermal expansion compensation between *** results serve to identify potential approaches for designing(Hf,Ta)Fe_(2)-based zero thermal expansion composites.
The phenomenon of spontaneous formation of quasihexagonal arrays of electric bubbles in systems of electric dipoles subjected to an external electric field bias is studied via ab initio-based simulations of ultrathin ...
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The phenomenon of spontaneous formation of quasihexagonal arrays of electric bubbles in systems of electric dipoles subjected to an external electric field bias is studied via ab initio-based simulations of ultrathin ferroelectric films. We find that the formation of such topologically nontrivial superstructures is driven by development and evolution of soft-mode triplets with equal wavelengths and eigenfrequencies. The concurrent development of these soft-modes takes place above the transition point and the soft-modes become frozen-in near the transition temperature, where frequencies of the soft modes attain a minimum value. A further gradual cooling (or heating) of the superstructures leads to an increase in the soft-mode frequencies, following a square root law around the transition point. We quantify the thermal behavior of the degree of quasihexagonal ordering and find that the dipole structure factor intensities show the same critical behavior around the transition point as the soft-mode frequencies. The critical behavior, associated with the topological changes, is consistent with the Landau theory of phase transitions.
Tungsten-bronze-type material Ba_(6-3x)RE_(8+2x)Ti_(18)O_(54),(RE=rare earth elements)is an important microwave dielectric that has shown great promises for future miniaturization of microwave devices because of its h...
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Tungsten-bronze-type material Ba_(6-3x)RE_(8+2x)Ti_(18)O_(54),(RE=rare earth elements)is an important microwave dielectric that has shown great promises for future miniaturization of microwave devices because of its high dielectric constant,low loss,and tunabilities,and there is still much room for *** their proven predictive power,first-principles calculations may greatly help accelerate materials optimization by reducing or eliminating the expensive and time-consuming experimental trial-and-error ***,microwave dielectrics such as the tungsten-bronzetype materials are rather complex systems with unit cells containing hundreds or thousands of atoms,making ab initio calculations prohibitively *** this work,we propose an elemental-unit decomposition(EUD)technique that can drastically reduce the computational effort of predicting the properties of complex microwave dielectrics and demonstrate its accuracy and *** approach facilitates first-principles prediction and design of complex microwave dielectric materials that would otherwise be extremely difficult.
The rapid development of sustainable green energy,which often generates fluctuating electrical signals,has driven the demand for high-performance filter capacitors in alternating/direct current *** bulky aluminum elec...
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The rapid development of sustainable green energy,which often generates fluctuating electrical signals,has driven the demand for high-performance filter capacitors in alternating/direct current *** bulky aluminum electrolytic capacitors with electric double-layer capacitors(EDLCs)holds promise for electronics ***,EDLCs face a trade-off between charge storage ability and ion/electron transport ***,we demonstrate three-dimensional Y-branched carbon tube(3D-YCT)grids with a hierarchically porous structure as electrodes for line-filtering *** branching patterns and positions within the 3D-YCT are precisely tailored through the nanochannels inside anodic aluminum oxide *** integrated 3D Y-branched CT arrays provide unobstructed pathways for fast frequency response and extensive surfaces for high *** resulting 3D-YCT-based EDLC achieves a desirable specific areal capacitance(C_(A))of 3.6 mF cm^(-2)with a phase angle of-80°at 120 Hz,outperforming most reported line-filtering EDLCs and demonstrating excellent line-filtering *** findings offer valuable insights for constructing miniaturized filter capacitors.
Direct electron detectors in scanning transmission electron microscopy give unprecedented possibilities for structure analysis at the *** electronic and quantum materials,this new capability gives access to,for exampl...
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Direct electron detectors in scanning transmission electron microscopy give unprecedented possibilities for structure analysis at the *** electronic and quantum materials,this new capability gives access to,for example,emergent chiral structures and symmetry-breaking distortions that underpin functional *** nanoscale structural features with statistical significance,however,is complicated by the subtleties of dynamic diffraction and coexisting contrast mechanisms,which often results in a low signal-to-noise ratio and the superposition of multiple signals that are challenging to deconvolute.
As global population rises,accompanied by escalating environmental pollution and climate change,numerous countries find themselves grappling with an acute scarcity of natural freshwater resources^([1]).Seawater desali...
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As global population rises,accompanied by escalating environmental pollution and climate change,numerous countries find themselves grappling with an acute scarcity of natural freshwater resources^([1]).Seawater desalination presents a compelling solution to this looming crisis,especially considering the oceans are Earth’s largest water reservoir^([2]).
Oxygen vacancies are one of the most common *** are imperfections in the regular geometrical arrangement of the atoms in crystalline *** are point defects,linear defects,plane defects and volume defects in *** an elem...
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Oxygen vacancies are one of the most common *** are imperfections in the regular geometrical arrangement of the atoms in crystalline *** are point defects,linear defects,plane defects and volume defects in *** an elemental crystal,point defects are formed when atoms are removed from the position that should be filled in the crystal,creating vacancies,or when atoms occupy interstitial sites where no atom would ordinarily appear,causing interstitialcy[1].
Electroreduction of nitrite to ammonia(NO_(2)RR)is recognized as an appealing method for achieving renewable NH_(3)production and waste NO_(2)^(-)***,monodispersed W-doped ZnO(W_(1-)ZnO)is develo ped as an efficient N...
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Electroreduction of nitrite to ammonia(NO_(2)RR)is recognized as an appealing method for achieving renewable NH_(3)production and waste NO_(2)^(-)***,monodispersed W-doped ZnO(W_(1-)ZnO)is develo ped as an efficient NO_(2)RR *** simulations and in situ spectroscopic measurements unravel that the enhanced NO_(2)RR property of W_(1)-ZnO originates from the creation of active W_(1)-Zn dinuclear sites to selectively activate NO_(2)^(-)and enhance the protonation energetics of NO_(2)^(-)to-NH_(3)pathway,whilst repelling the competing H_(2)***,W_(1)-ZnO equipped in flow cell shows an impressive NO_(2)RR performa nce with NH_(3)yield rate of 970μmol h^(-1)cm^(-2)and NH_(3)-Faradaic efficiency of 94.5%.
The generation and manipulation of spin-polarized electrons at room temperature are essential for the development of advanced spin-optoelectronic *** this work,a one-pot method was used to successfully synthesize homo...
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The generation and manipulation of spin-polarized electrons at room temperature are essential for the development of advanced spin-optoelectronic *** this work,a one-pot method was used to successfully synthesize homogenous Mn:CsPbBr_(3) perovskite quantum dots in air with particle sizes of 7−8 *** effects of Mn doping on the structure,optical and magnetic properties of CsPbBr_(3) quantum dots were *** findings demonstrated proper Mn doping improved the crystallinity and photoluminescence(PL)of quantum *** prepared quantum dots have a narrow full width at half maximum emission(FWHM)of about 17−20 *** magnetic properties of the doped samples and the effect of the magnetic field on the PL spectra properties were *** results show that trace Mn doping can improve the room-temperature ferromagnetism of CsPbBr_(3) quantum *** with magnetic elements makes CsPbBr_(3) quantum dots more responsive to the applied magnetic *** at a lower 50 mT magnetic field,the PL peak of Mn:CsPbBr_(3) still declined 5.91%.Mn:CsPbBr_(3) quantum dots are a new type of multifunctional material that is beneficial to spintronics *** work demonstrates a low-cost synthesis *** should make all-inorganic perovskite quantum dots a promising material for room-temperature spin optoelectronic devices.
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