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Electrochemical performances of MnO2/Fe3O4/activated carbon ternary composites for supercapacitor and direct ethanol fuel cell catalyst application

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RSC Advances 2025年第21期15卷 16493-16509页

作者： Dessie, Yilkal Bekele, Eneyew Tilahun Gonfa, Bedasa Abdisa Ravikumar, C.R. Khasim, Syed Abraham, Getahun Department of Applied Chemistry College of Applied Natural Science Adama Science and Technology University Adama1888 Ethiopia Research Centre Department of Science East-West Institute of Technology Bangalore560091 India Advanced Materials Research Laboratory Department of Physics Faculty of science University of Tabuk Tabuk71491 Saudi Arabia Department of Chemistry College of Natural and Computational Sciences Kebri Dehar University P.O. Box 250 Kebri Dehar Ethiopia

MnO2 and Fe3O4 nanoparticles' slow ion-diffusion kinetics and weak electrical conductivity hinder their electrochemical performance in supercapacitors and their energy-conversion ability in direct ethanol fuel cells (DAFCs). Combining MnO2/Fe3O4 with biomass-based activated carbon (AC), which is conductive, inexpensive, and has a long cycle life, to create MnO2/Fe3O4/AC can improve their electrochemical performances for ethanol oxidation and in supercapacitors. Herein, MnO2/Fe3O4/AC ternary composites were synthesized via a facile method. The physicochemical and electrochemical properties of pure and composite materials were characterized using TGA-DTA, XRD, FTIR, BET, SEM-EDX, TEM, HRTEM, SAED, CV, and EIS. The composite MnO2/Fe3O4@8%AC exhibited the highest specific capacitance, with a value of 515.113 F g−1 at 1 A g−1. Furthermore, in cyclability tests, after 700 cycles at a current density of 1 A g−1, its charge-storage performance showed an 81.83% capacity retention and a maximum energy density of 27.679 W h kg−1. Upon integration in a DAFC, MnO2/Fe3O4@8%AC electrocatalytic ethanol oxidation was achieved with a maximum power density of 44.41 mW cm−2, indicating better performance than that of other pure and composite catalysts. Therefore, this work provides a potential candidate for use in efficient energy-storage devices and an effective catalyst electrode for the ethanol oxidation reaction. © 2025 The Royal Society of Chemistry.

关键词： Electrochemical oxidation

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Structure inversion asymmetry enhanced electronic structure and electrical transport in 2D A3SnO(A=Ca,Sr,and Ba)antiperovskite monolayers

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Nano Research 2023年第1期16卷 1779-1791页

作者： Syed Muhammad Alay-e-Abbas Ghulam Abbas Waqas Zulfiqar Muhammad Sajjad Nirpendra Singh J.Andreas Larsson Applied Physics Division of Materials ScienceDepartment of Engineering Sciences and MathematicsLuleåUniversity of Technology97187 LuleåSweden Computational Materials Modeling Laboratory Department of PhysicsGovernment College UniversityFaisalabad 38040Pakistan Department of Energy Conversion and Storage Technical University of Denmark2800 Kgs.LyngbyDenmark Department of Physics Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates Center for Catalysis and Separation(CeCaS) Khalifa University of Science and TechnologyAbu Dhabi-127788United Arab Emirates

Anti-perovskites A3SnO(A=Ca,Sr,and Ba)are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry,spin–orbit coupling,and band *** provides an exciting playground for modulating their electronic properties in the two-dimensional(2D)***,we employ first-principles density functional theory(DFT)calculations by combining dispersion-corrected SCAN+rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural,thermodynamic,dynamical,mechanical,electronic,and thermoelectric properties of bulk and monolayer(one unit cell thick)A3SnO *** results show that 2D monolayers derived from bulk A3SnO anti-perovskites are structurally and energetically ***,Rashba-type splitting in the electronic structure of Ca3SnO and Sr3SnO monolayers is observed owing to strong spin–orbit coupling and inversion *** the other hand,monolayer Ba3SnO exhibits Dirac cone at the high-symmetryΓpoint due to the domination of band *** on the predicted electronic transport properties,it is shown that inversion asymmetry plays an essential character such that the monolayers Ca3SnO and Sr3SnO outperform thermoelectric performance of their bulk counterparts.

关键词： electrical transport anti-perovskites low-dimensional materials electronic structure mechanical properties

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Electronic structures and strengthening mechanisms of superhard high-entropy diborides

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Rare Metals 2023年第2期42卷 614-628页

作者： Gang Yao William-Yi Wang Pei-Xuan Li Ke Ren Jia-Qi Lu Xing-Yu Gao De-Ye Lin Jun Wang Yi-Guang Wang Hai-Feng Song Zi-Kui Liu Jin-Shan Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Innovation Center NPU ChongqingChongqing401135China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing100088China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing100081China Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity ParkPA16802USA

High-entropy diborides(HEBs)have attracted extensive research due to their potential ultra-high *** the present work,the effects of transition metals(TM)on lattice parameters,electron work function(EWF),bonding charge density,and hardness of HEBs are comprehensively investigated by the first-principles calculations,including(TiZrHfNbTa)B_(2),(TiZrHfNbMo)B_(2),(TiZrHfTaMo)B_(2),(TiZrNbTaMo)B_(2),and(TiHfNbTaMo)B_(2).It is revealed that the disordered TM atoms result in a severe local lattice distortion and the formation of weak *** view of bonding charge density,it is understood that the degree of electron contribution of TM atoms directly affects the bonding strength of the metallic layer,contributing to the optimized hardness of ***,the proposed power-law-scaled relationship integrating the EWF and the grain size yields an excellent agreement between our predicted results and those reported experimental *** is found that the HEBs exhibit relatively high hardness which is higher than those of single transition metal *** particular,the hardness of(TiZrNbTaMo)B_(2)and(TiHfNbTaMo)B_(2)can be as high as29.15 and 28.02 GPa,*** work provides a rapid strategy to discover/design advanced HEBs efficiently,supported by the coupling hardening mechanisms of solid solution and grain refinement based on the atomic and electronic interactions.

关键词： High-entropy diborides(HEBs) Hardness Electronic structure Lattice distortion Power-law

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Correlations in interacting electron liquids: Many-body statistics and hyperuniformity

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Physical Review B 2024年第10期110卷 104201页

作者： Haina Wang Rhine Samajdar Salvatore Torquato Department of Chemistry Department of Physics Princeton Center for Theoretical Science Princeton Materials Institute Program in Applied and Computational Mathematics

Disordered hyperuniform many-body systems are exotic states of matter with novel optical, transport, and mechanical properties. These systems are characterized by an anomalous suppression of large-scale density fluctuations compared to ordinary liquids. The structure factor of disordered hyperuniform systems often obeys the scaling relation S(k)∼Bkα with B,α>0 in the limit k→0. Ground states of d-dimensional free fermionic gases, which are fundamental models for many metals and semiconductors, are key examples of quantum disordered hyperuniform states with important connections to random matrix theory. However, the effects of electron-electron interactions as well as the polarization of the electron liquid on hyperuniformity have not been explored thus far. In this paper, we systematically address these questions by deriving the analytical small-k behaviors (and, associated, α and B) of the total and spin-resolved structure factors of quasi-one-dimensional, two-dimensional, and three-dimensional electron liquids for varying polarizations and interaction parameters. We validate that these equilibrium disordered ground states are hyperuniform, as dictated by the fluctuation-compressibility relation. Interestingly, free fermions, partially polarized interacting fermions, and fully polarized interacting fermions are characterized by different values of the small-k scaling exponent α and coefficient B. In particular, partially polarized fermionic liquids exhibit a unique form of multihyperuniformity, in which the net configuration exhibits a stronger form of hyperuniformity (i.e., larger α) than each individual spin component. The detailed theoretical analysis of such small-k behaviors enables the construction of corresponding equilibrium classical systems under effective one- and two-body interactions that mimic the pair statistics of quantum electron liquids. Our paper thus reveals that highly unusual hyperuniform and multihyperuniform states can be achieved in simple

关键词： Electronic structure Quantum many-body systems Two-dimensional electron gas

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First-principles electron-phonon interactions and polarons in the parent cuprate La2CuO4

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Physical Review Research 2025年第1期7卷 L012073-L012073页

作者： Benjamin K. Chang Iurii Timrov Jinsoo Park Jin-Jian Zhou Nicola Marzari Marco Bernardi Department of Applied Physics and Materials Science and Department of Physics California Institute of Technology Pasadena California 91125 USA PSI Center for Scientific Computing Theory and Data Paul Scherrer Institut 5232 Villigen PSI Switzerland Department of Physics Pohang University of Science and Technology Pohang 37673 Korea School of Physics Beijing Institute of Technology Beijing 100081 China Theory and Simulation of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL) École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland

Understanding electronic interactions in high-temperature superconductors is an outstanding challenge. In the widely studied cuprate materials, experimental evidence points to strong electron-phonon (e-ph) coupling and broad photoemission spectra. Yet, the microscopic origin of this behavior is not fully understood. Here, we study e-ph interactions and polarons in a prototypical parent (undoped) cuprate, La2CuO4 (LCO), by means of first-principles calculations. Leveraging parameter-free Hubbard-corrected density functional theory, we obtain a ground state with the band gap and Cu magnetic moment in nearly exact agreement with experiments. This enables a quantitative characterization of e-ph interactions. Our calculations reveal two classes of longitudinal optical (LO) phonons with strong e-ph coupling to hole states. These modes consist of bond stretching and bond bending in the Cu-O plane as well as vibrations of apical O atoms. The hole spectral functions, obtained with a cumulant method that can capture strong e-ph coupling, exhibit broad quasiparticle peaks with a small spectral weight (Z≈0.25) and pronounced LO-phonon sidebands characteristic of polaron effects. Our calculations predict features observed in photoemission spectra, including a 40-meV peak in the e-ph coupling distribution function not explained by existing models. These results show that the universal strong e-ph coupling found experimentally in doped lanthanum cuprates is also present in the parent compound, and elucidate its microscopic origin.

关键词： High temperature superconductors

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Taenia solium taeniasis and cysticercosis:extinction or outbreak

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Animal Diseases 2023年第2期3卷 90-103页

作者： Jacob I.Irunde Faraja B.Luhanda Department of Mathematics Physics and InformaticsMkwawa University College of EducationIringaTanzania Department of Applied Mathematics and Computational Sciences The Nelson Mandela African Institution of Science and TechnologyArushaTanzania

Taenia solium taeniasis and cysticercosis are neglected zoonotic diseases that affect human health and economies of developing *** this work,we formulate and analyze deterministic and continuous time Markov chain(CTMC)stochastic models to determine parameters that drive Taenia solium taeniasis and cysticercosis and the likelihood of their *** basic reproduction number R0 is computed by the next generation matrix approach,sensitivity index of each parameter in R0 is derived by the normalized forward sensitivity index and the likelihood of diseases’extinction is computed by the multitype branching *** analysis shows that humans with Taenia solium taeniasis,infectious pork and Taenia solium eggs in the environment play an important role in the transmission of Taenia solium taeniasis and cysticercosis,and the model exhibits forward bifurcation at R0=*** implies that R0<1 is a sufficient condition to eliminate Taenia solium taeniasis and *** CTMC model,analysis shows that the probability of Taenia solium taeniasis and cysticercosis extinction is high if the diseases emerge from humans with Taenia solium cysticercosis and there is an outbreak if the diseases emerge from either humans with Taenia solium taeniasis or infectious pork or Taenia solium eggs in the *** control Taenia solium taeniasis and cysticercosis,the intervention strategies should focus on improving hygiene and sanitation for reducing shedding rate of Taenia solium eggs in the environment,inspection of pork for reducing the rate of acquiring Taenia solium taeniasis and spraying of insecticides for killing Taenia solium eggs in the environment.

关键词： Taeniasis Cysticercosis Basic reproduction number Sensitivity analysis Multitype branching process Stochastic model

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Approximating reproduction numbers: a general numerical method for age-structured models

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Mathematical Biosciences and Engineering 2024年第4期21卷 5360-5393页

作者： De Reggi, Simone Scarabel, Francesca Vermiglio, Rossana Department of Mathematics Computer Science and Physics University of Udine via delle Scienze 206 Udine33100 Italy Department of Applied Mathematics University of Leeds Woodhouse LeedsLS2 9JT United Kingdom CDLab – Computational Dynamics Laboratory University of Udine Italy

In this paper, we introduce a general numerical method to approximate the reproduction numbers of a large class of multi-group, age-structured, population models with a finite age span. To provide complete flexibility in the definition of the birth and transition processes, we propose an equivalent formulation for the age-integrated state within the extended space framework. Then, we discretize the birth and transition operators via pseudospectral collocation. We discuss applications to epidemic models with continuous and piecewise continuous rates, with different interpretations of the age variable (e.g., demographic age, infection age and disease age) and the transmission terms (e.g., horizontal and vertical transmission). The tests illustrate that the method can compute different reproduction numbers, including the basic and type reproduction numbers as special cases. c 2024 the Author(s), licensee AIMS Press.

关键词： Numerical methods

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Detailed discussion of discrepancy between theoretical and observed spectral lines in Kr-like W^(38+)based on advanced consideration of core electron correlations

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Chinese physics B 2025年第5期34卷 328-337页

作者： Guo-Qing Peng Kai Wang Jun Yan Wei Kang Center for Applied Physics and Technology Peking UniversityBeijing 100871China Department of Physics and Anhui Key Laboratory of Optoelectric Materials Science and Technology Key Laboratory of Functional Molecular SolidsMinistry of EducationAnhui Normal UniversityWuhu 241000China Institute of Applied Physics and Computational Mathematics Beijing 100088China

For the observed line at 799.23°A in tungsten EBIT experiment,which was assigned to be^(3)F_(4)^(o)−^(3)F_(3)^(o)([Ar]4s^(2)4p^(5)4d)of W^(38+)ion,there were noticeable deviations for most calculated wavelengths from the measured *** clarify this issue,we carry out an extensive calculation for energy levels and transition properties of W^(38+)ion using the multi-configuration Dirac–Hartree–Fock and relativistic configuration interaction method,in which more deeper inner core electron correlations are included,and different forms of Breit interaction as well as quantum electrodynamics corrections are *** is found that the inner core electron correlations can affect the total energy of levels,while only slightly modify the excited energy of levels in 4s^(2)4p^(5)4d *** present calculated wavelengths agree with the corresponding measured values excellently except the line at 799.23Å.Thus we are strongly suspicious this line should be misidentified,and suggest that new experiment with higher resolution and spectra analysis based on more accurate atomic data should be performed for W^(38+)ion.

关键词： Kr-like W^(38+) the multi-configuration Dirac-Hartree-Fock(MCDHF)method electron correlation imbalance Breit interaction quantum electrodynamic(QED)

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Local order metrics for many-particle systems across length scales

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Physical Review Research 2024年第3期6卷 033262页

作者： Charles Emmett Maher Salvatore Torquato Department of Chemistry Department of Physics Princeton Institute for the Science and Technology of Materials Program in Applied and Computational Mathematics

Formulating order metrics that sensitively quantify the degree of order/disorder in many-particle systems in d-dimensional Euclidean space Rd across length scales is an outstanding challenge in physics, chemistry, and materials science. Since an infinite set of n-particle correlation functions is required to fully characterize a system, one must settle for a reduced set of structural information, in practice. We initiate a program to use the local number variance σN2(R) associated with a spherical sampling window of radius R (which encodes pair correlations) and an integral measure derived from it ΣN(Ri,Rj) that depends on two specified radial distances Ri and Rj. Across the first three space dimensions (d=1,2,3), we find these metrics can sensitively describe and categorize the degree of order/disorder of 41 different models of antihyperuniform, nonhyperuniform, disordered hyperuniform, and ordered hyperuniform many-particle systems at a specified length scale R. Using our local variance metrics, we demonstrate the importance of assessing order/disorder with respect to a specific value of R. These local order metrics could also aid in the inverse design of structures with prescribed length-scale-specific degrees of order/disorder that yield desired physical properties. In future work, it would be fruitful to explore the use of higher-order moments of the number of points within a spherical window of radius R [S. Torquato et al., Phys. Rev. X 11, 021028 (2021)] to devise even more sensitive order metrics.

关键词： Classical statistical mechanics

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Majorana stellar representation for mixed-spin (s, 1/2) systems

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Chinese physics B 2021年第3期30卷 168-175页

作者： Yu-Guo Su Fei Yao Hong-Bin Liang Yan-Ming Che Li-Bin Fu Xiao-Guang Wang Zhejiang Province Key Laboratory of Quantum Technology and Device Department of PhysicsZhejiang UniversityHangzhou 310027China National Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China

By describing the evolution of a quantum state with the trajectories of the Majorana stars on a Bloch sphere,Majorana’s stellar representation provides an intuitive geometric perspective to comprehend the quantum system with highdimensional Hilbert ***,the representation of a two-spin coupling system on a Bloch sphere has not been solved satisfactorily ***,a practical method is presented to resolve the problem for the mixed-spin(s,1/2)system and describe the entanglement of the *** system can be decomposed into two spins:spin-(s+1/2)and spin-(s−1/2)at the coupling bases,which can be regarded as independent ***,any pure state may be written as a superposition of two orthonormal states with one spin-(s+1/2)state and the other spin-(s−1/2)***,the whole initial state can be regarded as a state of a pseudo spin-1/*** this way,the mixed spin decomposes into three ***,the state can be represented by(2s+1)+(2s−1)+1=4s+1 sets of stars on a Bloch ***,some examples are given to show symmetric patterns on the Bloch sphere and unveil the properties of the high-spin system by analyzing the trajectories of the Majorana stars on the Bloch sphere.

关键词： Majorana’s stellar representation Bloch sphere high-dimensional projective Hilbert space mixedspin

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