Fabricating perovskite oxide/carbon material composite catalysts is a widely accepted strategy to enhance oxygen reduction reaction/oxygen evolution reaction (ORR and OER) catalytic activities. ...Herein, synthesized, porous, perovskite‐type Sm0.5Sr0.5CoO3‐δ hollow nanofibers (SSC‐HF) are hybridized with cross‐linked, 3D, N‐doped graphene (3DNG). This rationally designed hybrid catalyst, SSC‐HF‐3DNG (SSC‐HG), exhibits a remarkable enhancement in ORR/OER activity in alkaline media. The synergistic effects between SSC and 3DNG during their ORR and OER processes are firstly revealed by density functional theory calculations. It suggests that electron transport from 3DNG to O2 and SSC increases the activity of electrocatalytic reactions (ORR and OER) by activating O2, increasing the covalent bonding of lattice oxygen. This electron transfer–accelerated catalysis behavior in SSC‐HG will provide design guidelines for composites of perovskite and carbon with bifunctional catalysts.
A perovskite oxide, Sm0.5Sr0.5CoO3‐δ hollow nanofibers and 3D porous N‐doped graphene are fabricated into a composite bifunctional electrocatalyst, which exhibits great enhancement of oxygen reduction reaction and oxygen evolution reaction activities. The mechanism of synergistic effects between perovskite oxides and N‐doping graphene for the better designing of this kind of composite electrocatalyst is revealed.
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The linear canonical wavelet transform is a nontrivial generalization of the classical wavelet transform in the context of the linear canonical transform. In this article, we first present a direct ...interaction between the linear canonical transform and Fourier transform to obtain the generalization of the uncertainty principles related to the linear canonical transform. We develop these principles for constructing some uncertainty principles concerning the linear canonical wavelet transform.
This paper presents a multigigahertz active clock deskewing architecture that uses analog phase interpolation to replace the area-consuming capacitively controlled delay lines used in regional clock ...deskewing delay-locked loops. It provides a small phase step that is uniform and process-independent over the entire 2ϖ phase deskew range, which reduces the intra-die clock skew. The phase interpolators have virtually zero latency, which leads to a very fast clock deskewing process and allows for the tracking of fast dynamic variations. A bandgap referencing technique was used to provide a tracking mechanism between the phase-locked loop (PLL) time constants to achieve a process-independent PLL damping factor and pole-zero separation. Both feedback and input divider modulus independence of the damping factor was achieved through a combined current and capacitor switching architecture, that provides an optimal compromise between area, power, and spurs. A reset-generation charge-pump architecture was introduced to minimize the dead-zone avoidance pulse width in order to improve the PLL jitter and reference spurs performance. The power supply partitioning exploits the dual gate oxide transistors offered by the current deep-submicron CMOS technologies. The biasing scheme is comprised of a 1.5-V supply for the ring oscillator and digital circuitry for speed considerations, while the analog front-end is biased from a 2.5-V supply to ensure more voltage headroom as required by low-gain oscillators and low-noise loop filters.
Notice of Violation of IEEE Publication Principles "A 0.16-2.55-GHz CMOS active clock deskewing PLL using analog phase interpolation" by Maxim, A. in the IEEE Journal of Solid-State Circuits, Volume 40, Issue 1, Jan. 2005 Page(s):110 - 131 After careful and considered review, it has been determined that the above paper is in violation of IEEE's Publication Principles. Specifically, the paper contains information that Adrian Maxim admits had been falsified. In response to an inquiry on this misconduct, Mr. Maxim acknowledged that the following people who have been listed as co-authors on several of his papers are fabricated names and that he is the only author: C. Turinici, D. Smith, S. Dupue Additionally, in papers by Mr. Maxim that have co-authors other than those listed above, it was discovered in some cases that he had not consulted with them while writing the papers, and submitted papers without their knowledge. Although Mr. Maxim maintains that not all of the data is falsified, IEEE nevertheless cannot assure the integrity of papers posted by him because of his repeated false statements. Due to the nature of this violation, reasonable effort should be made to remove all past references to the above paper, and to refrain from any future references.
Using first principles study, we have investigated the hydrogen storage capacity of Ca-coated B40. Our result shows that Ca prefers to adsorb on the top hollow center of heptagonal ring of B40 due to ...the large binding energy of −2.820 eV. Bader charges calculation indicates that charges transfer from Ca to B40 result in an induced electric field so that H2 molecules are polarized and adsorbed onto the surface of B40 without dissociation. The Ca6B40 complex can adsorb up to 30 H2 molecules with average adsorption energy of −0.177 eV/H2 and the hydrogen storage gravimetric density reaches up to 8.11 wt.%, higher than the goal from DOE by the year 2020. These findings will suggest a new and potential structure for hydrogen storage in the future.
The electrostatic potential contours of 30H2@Ca6B40 configuration and the blue and red colors represent the positive and negative value of electrostatic potential. Display omitted
•The metal clustering is avoided due to the large binding energy for Ca atoms.•The desirable adsorption energy of H2 molecules is −0.177 eV/H2 within the suitable range.•The hydrogen storage gravimetric density reaches up to 8.11 wt.%, higher than the target from DOE by the year 2020.
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Janus MoSSe monolayer has been widely considered as an appealing anode for lithium-ion batteries (LIBs), owing to its suitable open circuit voltage, low diffusion barrier and high specific capacity. ...However, Janus MoSSe suffers from low electrical conductivity and poor mechanical property, resulting in a rapid capacity decay during cycling. Thus, in this work, we proposed two MoSSe/graphene (SMoSe/G and SeMoS/G) heterostructures as anodes of LIBs, which not only eliminate the drawbacks of MoSSe but also integrate the advantages of individual components. By means of first principles computations, we have systematically investigated the structural, electronic, mechanical and electrochemical properties of MoSSe/graphene heterostructures. Our results show that MoSSe/graphene heterostructures possess good structural stability, superior Li-ion conductivity and high mechanical stiffness (Yx(y),SMoSe/G=459.8 N/m; Yx(y),SeMoS/G = 459.3 N/m). Due to the synergistic effect between MoSSe and graphene, the adsorption energies of Li in heterostructures are much larger than those of pristine MoSSe and graphene. Accordingly, the MoSSe/G heterostructures achieve a high theoretical capacity of 560.59 mA h/g. Moreover, the diffusion barriers in SMoSe/G and SeMoS/G heterostructures are 0.17 and 0.22 eV, respectively, ensuring high mobility of Li. All these encouraging results demonstrate that the MoSSe/graphene heterostructures are high-performance anodes for advanced LIBs.
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•A detailed investigation of MoSSe/G heterostructures as LIB anodes are carried out.•Improved electrical conductivity and mechanical stiffness are observed in the MoSSe/G heterostructures.•The MoSSe/G heterostructures possess a high specific capacity of 560.59 mA h/g and suitable open circuit voltage.•The diffusion barriers of SMoSe/G and SeMoS/G heterostructures are 0.17 and 0.22 eV, respectively.
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Institutionalization of law-making principles is the most important state task to give to the law-making the task-oriented formation, to enforce legally state’s social purpose and development ways. ...The scientific perception of this principle should be enforced in legal act framework without which the principle itself shall not be valuable and alive. Institutionalization of law-making principles is preservation in legal norms the basic ideas, social and other values as the leading landmarks to regulate public relationships in order to form the social stability and development in the state. The formal figuration of law-making principles cannot be conceptualized unless solved in view of the legal regulation extent.
In this work the electronic and optical properties of luminescent materials XSiN2 (X = Ca, Sr, Ba) were revisited based on density function theory (DFT) calculations with a newly developed DFT-1/2 ...scheme. It was found that the DFT-1/2 correction on nitrogen can well correct the band gaps to approach the experimental values, showing its advantage comparing to the Perdew–Burke–Ernzerhof (PBE) and the Strongly Constrained and Appropriately Normed (SCAN) functionals. Then the electronic band structures and optical properties of the three compounds were investigated using the DFT-1/2 scheme. Within the three compounds, the band gap shows a monotonic decrease along with the atomic number of alkali earth metal mainly due to the downshift of the conduction band edge, where the electronic conductivity is primarily based on electron since it shows a much smaller effective mass than hole. CaSiN2 owns more flat valence bands, while SrSiN2 gives lighter electron. Moreover, the three compounds show high optical absorption, but distinct behavior of light absorption and refractivity in specific energy range, suggesting their applications in optical applications.
•A more accurate method was chosen to address the band gap of XSiN2 (X=Ca,Sr,Ba).•The physical properties were computationally investigated using this approach.•The compounds are predicted to be good candidates for luminescent application.
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The double perovskites, as a novel material with promising applications in solar cells, have garnered significant research interest. The mechanical, electrical, optical, and thermodynamic ...characteristics of Cs2OsI6 are systematically studied using first-principles calculations. The material's mechanical stability satisfies the Born criteria, and it exhibits commendable elasticity and anisotropy. The application of the HSE06 hybrid functional reveals that Cs2OsI6 has a direct band gap of 1.14 eV at the Γ-point, with electronic states primarily originating from the I-p orbitals and Os-d orbitals. The optical properties, including the dielectric function, refractive index, and absorption coefficient, indicate that it has a strong UV absorption capacity. The thermodynamic properties, including the Debye temperature, heat capacity, enthalpy, entropy, and free energy, conform to the laws of thermodynamics. The results indicate that Cs2OsI6 exhibits good stability with changes in temperature. In addition, it has a suitable band gap and a strong light absorption coefficient, making it suitable for photovoltaic applications. It has great potential to be a candidate for perovskite solar cell materials.
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The structural stability, electronic, and mechanical properties of Ti1-xMx (M = Fe, Mo, Nb, Ni) binary alloys were systematically investigated through first-principles calculations based on Density ...Functional Theory (DFT). The results indicate that the formation energy decreased with an increase in the substitutional atomic M content, accompanied by an increase in the values of C11–C12. This observation suggests a significant improvement in the structural stability of the Ti1-xMx alloys considered, with the concentration of substitutional atomic M ranging from 6.25 % to 50 %. Furthermore, the mechanical parameters, including bulk modulus B and shear modulus G, exhibited a linear increase with the concentration of the alloy element M. The Young's modulus E of Ti1-xFex and Ti1-xNbx alloys increased, whereas Ti1-xMox and Ti1-xNbx alloys reached a minimum value. In addition, the B/G ratio and Poisson's ratio ν indicated that β-Ti1-xMx alloys are fundamentally ductile materials. Moreover, using the stretching model, we demonstrate that the tensile strength of Ti1-xMx alloys was significantly improved by increasing the alloy element M concentration. The enhancement in tensile strength was primarily attributed to the enhanced bond strength between Ti and M atoms, as revealed by the analysis of the density state. These findings provide a pragmatic approach for reinforcing the strength-toughness compatibility of Ti-based alloys, rendering them suitable for aerospace industry applications.
•This work suggest that the considered alloying elements M (M = Fe, Mo, Nb, Ni) improve the structural stability of β-phase Ti alloys.•The mechanical parameters, including bulk modulus B and shear modulus G, exhibited a linear increase with the concentration of the alloy element M.•The results indicate that the addition of alloying elements M can enhance the tensile strength of β-Ti alloys while simultaneously maintaining toughness.
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The further practical applications of halide perovskite quantum dots (QDs) are blocked by problems of instability and nonradiative Auger recombination manifested as photoluminescence blinking. Here, ...single core/shell structured perovskite semiconductor QDs are successfully fabricated by capping CsPbBr3 QD core with CdS shell. It is demonstrated that CsPbBr3/CdS core/shell QDs exhibit ultrahigh chemical stability and nonblinking photoluminescence with high quantum yield due to the reduced electronic traps within the core/shell structure. Efficiency of amplified spontaneous emission exhibits obvious enhancement compared to that of pure CsPbBr3 QDs, originating from the mitigated competition between stimulated emission and suppressed nonradiative biexciton Auger recombination. Furthermore, low‐threshold whispering‐gallery‐mode lasing with a high‐quality factor is achieved by incorporating CsPbBr3/CdS QDs into microtubule resonators. Density functional theory (DFT)‐based first‐principles calculations are also performed to reveal the atomic interface structure, which supports the existence of CsPbBr3/CdS structure. An interesting feature of spatially separated charge density at CsPbBr3/CdS interface is found, which may greatly contribute to the suppressed Auger recombination. The results provide a practical approach to improve the stability and suppress the blinking of halide perovskite QDs, which may pave the way for future applications for various optoelectronic devices.
Single CsPbBr3/CdS core/shell quantum dots are successfully fabricated and demonstrated by combining materials synthesis, characterization, optical measurements, and first‐principles calculations, which show ultrahigh stability and nonblinking photoluminescence with high quantum yield. Exotic interfacial electronic structures within the core/shell structures contribute to their interesting physical behaviors, such as low‐threshold whispering‐gallery‐mode lasing.
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