The application of homogeneous electrocatalytic reactions in energy storage and conversion has driven surging interests of researchers in exploring the reaction mechanisms of molecular catalysts.In this paper,homogene...The application of homogeneous electrocatalytic reactions in energy storage and conversion has driven surging interests of researchers in exploring the reaction mechanisms of molecular catalysts.In this paper,homogeneous electrocatalytic reaction between hydroxymethylferrocene(HMF)and L-cysteine is intensively investigated by cyclic voltammetry and square wave voltammetry for which,the secondorder rate constant(k_(ec))of the chemical reaction between HMF^(+)and L-cysteine is determined via a 1D homogeneous electrocatalytic reaction model based on finite element simulation.The corresponding k_(ec)(1.1(mol·m^(-3))^(-1)·s^(-1))is further verified by linear sweep voltammograms under the same model.Square wave voltammetry parameters including potential frequency(f),increment(Estep)and amplitude(ESW)have been comprehensively investigated in terms of the voltammetric waveform transition of homogeneous electrocatalytic reaction.Specifically,the effect of potential frequency and increment is in accordance with the potential scan rate in cyclic voltammetry and the increase of pulsed potential amplitude results in a conspicuous split oxidative peaks phenomenon.Moreover,the proposed methodology of k_(ec)prediction is examined by hydroxyethylferrocene(HEF)and L-cysteine.The present work facilitates the understanding of homogeneous electrocatalytic reaction for energy storage purpose,especially in terms of electrochemical kinetics extraction and flow battery design.展开更多
Greatly stable thermodynamics and sluggish kinetics impede the practical application of Mg-based hydrogen storage alloys.The modifications of composition and structure are important strategies in turning these hydroge...Greatly stable thermodynamics and sluggish kinetics impede the practical application of Mg-based hydrogen storage alloys.The modifications of composition and structure are important strategies in turning these hydrogen storage properties.In this study,Mg-based Mg90Ce5 Sm5 ternary alloy fabricated by vacuum induction melting was investigated to explore the performance and the reaction mechanism as hydrogen storage material by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM) and pressure-composition isotherms(PCI) measurements.The results indicate that the Mg-based Mg90Ce5 Sm5 ternary alloy consists of two solid solution phases,including the major phases(Ce,Sm)5 Mg41 and the minor phases(Ce,Sm)Mg12.After hydrogen absorption,these phases transform into the MgH2 and(Ce,Sm)H2.73 phase,while after hydrogen desorption,the MgH2 transforms into the Mg phase,but the(Ce,Sm)H2.73 phases are not changed.The alloy has a reversible hydrogen capacity of about 5.5 wt% H2 and exhibits well isothermal hydrogen absorption kinetics.Activation energy of 106 kJ/mol was obtained from the hydrogen desorption data between 573 and 633 K,which also exhibits the enhanced kinetics compared with the pure MgH2 sample,as a result of bimetallic synergy catalysis function of(Ce,Sm)H2.73 phases.The rate of hydrogen desorption is controlled by the release and recombination of H2 from the Mg surface.Furthermore,the changes of enthalpy and entropy of hydrogen absorption/desorption were calculated to be-80.0 kJ/mol H2,-137.5 J/K/mol H2 and 81.2 kJ/mol H2,139.2 J/K/mol H2,respectively.展开更多
Living organisms derive energy for cellular activities through three primary mechanisms. The first is photosynthesis, which is restricted to plants and certain bacteria. It uses energy in sunlight to combine carbon di...Living organisms derive energy for cellular activities through three primary mechanisms. The first is photosynthesis, which is restricted to plants and certain bacteria. It uses energy in sunlight to combine carbon dioxide with water to form carbohydrates plus oxygen. The second is chemical energy, which is ob-tainable by all organisms from the cellular metabolism of carbohydrates and other organic molecules. The third mechanism of obtaining cellular energy is the alternative cellular energy (ACE) pathway. The ACE pathway is expressed as an added dynamic (kinetic) quality of the body’s fluids. It results from the absorption of an environmental force termed KELEA (kinetic energy limiting electrostatic attraction). The fundamental role of KELEA is presumably to pre-vent the fusion and annihilation of electrostatically attracted opposing electrical charges. KELEA can loosen the hydrogen bonding between fluid molecules. KELEA benefits living organisms in part by enabling more efficient biochemical reactions. Cells require a minimal amount of energy to remain viable. Additional energy is required to undertake specialized cellular functions. Illnesses result if cells have insufficient cellular energy (ICE) for their specialized functions. Since KELEA is attracted to separated electrical charges, it is presumably attracted to the electrical charges comprising the membrane potential of cells. It is proposed that the depolarization of neuronal cells leads to the partial release of KELEA for use by the depolarized cell and as a contribution to the overall activation of the body’s fluids. Many brain illnesses currently attributed to cellular neurodegeneration are explainable as neuronal cells’ adaptations to ICE. The adaptations likely comprise initial hyper-excitability to obtain additional KELEA, followed by functional quiescence prior to actual neuronal cell death. Clinical recovery during both the hyper-excitable and hypoactive phases is potentially achievable by enhancing the ACE pathway. Furthermore, among the restored specialized functions of quiescent neuronal cells may be the capacity to again attract KELEA, leading to sustainable recovery. The opportunity exists for extended clinical trials involving the ACE pathway in neurological and psychiatric illnesses.展开更多
基金the support of National Natural Science Foundation of China, China (Grant No. 22005010)Beijing Municipal Education Commission Research Project (KM202010005012)
文摘The application of homogeneous electrocatalytic reactions in energy storage and conversion has driven surging interests of researchers in exploring the reaction mechanisms of molecular catalysts.In this paper,homogeneous electrocatalytic reaction between hydroxymethylferrocene(HMF)and L-cysteine is intensively investigated by cyclic voltammetry and square wave voltammetry for which,the secondorder rate constant(k_(ec))of the chemical reaction between HMF^(+)and L-cysteine is determined via a 1D homogeneous electrocatalytic reaction model based on finite element simulation.The corresponding k_(ec)(1.1(mol·m^(-3))^(-1)·s^(-1))is further verified by linear sweep voltammograms under the same model.Square wave voltammetry parameters including potential frequency(f),increment(Estep)and amplitude(ESW)have been comprehensively investigated in terms of the voltammetric waveform transition of homogeneous electrocatalytic reaction.Specifically,the effect of potential frequency and increment is in accordance with the potential scan rate in cyclic voltammetry and the increase of pulsed potential amplitude results in a conspicuous split oxidative peaks phenomenon.Moreover,the proposed methodology of k_(ec)prediction is examined by hydroxyethylferrocene(HEF)and L-cysteine.The present work facilitates the understanding of homogeneous electrocatalytic reaction for energy storage purpose,especially in terms of electrochemical kinetics extraction and flow battery design.
基金the National Natural Science Foundation of China(51901105,51871125,51761032)Natural Science Foundation of Inner Mongolia,China(2019BS05005)。
文摘Greatly stable thermodynamics and sluggish kinetics impede the practical application of Mg-based hydrogen storage alloys.The modifications of composition and structure are important strategies in turning these hydrogen storage properties.In this study,Mg-based Mg90Ce5 Sm5 ternary alloy fabricated by vacuum induction melting was investigated to explore the performance and the reaction mechanism as hydrogen storage material by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM) and pressure-composition isotherms(PCI) measurements.The results indicate that the Mg-based Mg90Ce5 Sm5 ternary alloy consists of two solid solution phases,including the major phases(Ce,Sm)5 Mg41 and the minor phases(Ce,Sm)Mg12.After hydrogen absorption,these phases transform into the MgH2 and(Ce,Sm)H2.73 phase,while after hydrogen desorption,the MgH2 transforms into the Mg phase,but the(Ce,Sm)H2.73 phases are not changed.The alloy has a reversible hydrogen capacity of about 5.5 wt% H2 and exhibits well isothermal hydrogen absorption kinetics.Activation energy of 106 kJ/mol was obtained from the hydrogen desorption data between 573 and 633 K,which also exhibits the enhanced kinetics compared with the pure MgH2 sample,as a result of bimetallic synergy catalysis function of(Ce,Sm)H2.73 phases.The rate of hydrogen desorption is controlled by the release and recombination of H2 from the Mg surface.Furthermore,the changes of enthalpy and entropy of hydrogen absorption/desorption were calculated to be-80.0 kJ/mol H2,-137.5 J/K/mol H2 and 81.2 kJ/mol H2,139.2 J/K/mol H2,respectively.
文摘Living organisms derive energy for cellular activities through three primary mechanisms. The first is photosynthesis, which is restricted to plants and certain bacteria. It uses energy in sunlight to combine carbon dioxide with water to form carbohydrates plus oxygen. The second is chemical energy, which is ob-tainable by all organisms from the cellular metabolism of carbohydrates and other organic molecules. The third mechanism of obtaining cellular energy is the alternative cellular energy (ACE) pathway. The ACE pathway is expressed as an added dynamic (kinetic) quality of the body’s fluids. It results from the absorption of an environmental force termed KELEA (kinetic energy limiting electrostatic attraction). The fundamental role of KELEA is presumably to pre-vent the fusion and annihilation of electrostatically attracted opposing electrical charges. KELEA can loosen the hydrogen bonding between fluid molecules. KELEA benefits living organisms in part by enabling more efficient biochemical reactions. Cells require a minimal amount of energy to remain viable. Additional energy is required to undertake specialized cellular functions. Illnesses result if cells have insufficient cellular energy (ICE) for their specialized functions. Since KELEA is attracted to separated electrical charges, it is presumably attracted to the electrical charges comprising the membrane potential of cells. It is proposed that the depolarization of neuronal cells leads to the partial release of KELEA for use by the depolarized cell and as a contribution to the overall activation of the body’s fluids. Many brain illnesses currently attributed to cellular neurodegeneration are explainable as neuronal cells’ adaptations to ICE. The adaptations likely comprise initial hyper-excitability to obtain additional KELEA, followed by functional quiescence prior to actual neuronal cell death. Clinical recovery during both the hyper-excitable and hypoactive phases is potentially achievable by enhancing the ACE pathway. Furthermore, among the restored specialized functions of quiescent neuronal cells may be the capacity to again attract KELEA, leading to sustainable recovery. The opportunity exists for extended clinical trials involving the ACE pathway in neurological and psychiatric illnesses.
