Energy Of Hydrogen Atom Research Articles

Interfacial coordination bonds accelerate charge separation for unprecedented hydrogen evolution over S-scheme heterojunction

Inspired by natural photosynthesis, fabricating high-performance S-scheme heterojunction is regarded as a successful tactic to address energy and environmental issues. Herein, NH2-MIL-125(Ti)/Zn0.5Cd0.5S/NiS (NMT/ZCS/NiS) S-scheme heterojunction with interfacial coordination bonds is successfully synthesized through in-situ solvothermal strategy. Notably, the optimal NMT/ZCS/NiS S-scheme heterojunction exhibits comparable photocatalytic H2 evolution (PHE) rate of about 14876.7 μmol h−1 g−1 with apparent quantum yield of 24.2% at 420 nm, which is significantly higher than that of recently reported MOFs-based photocatalysts. The interfacial coordination bonds (Zn–N, Cd–N, and Ni–N bonds) accelerate the separation and transfer of photogenerated charges, and the NiS as cocatalyst can provide more catalytically active sites, which synergistically improve the photocatalytic performance. Moreover, theoretical calculation results display that the construction of NMT/ZCS/NiS S-scheme heterojunction also optimize the binding energy of active site-adsorbed hydrogen atoms to enable fast adsorption and desorption. Photoassisted Kelvin probe force microscopy, in-situ irradiation X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy, and theoretical calculations provide sufficient evidence of the S-scheme charge migration mechanism. This work offers unique viewpoints for simultaneously accelerating the charge dynamics and optimizing the binding strength between the active sites and hydrogen adsorbates over S-scheme heterojunction.

Quantification of Hydrogen and Transition Metals in the Cathode Catalyst Layer of Anion Exchange Membrane Electrolyzer By Ion Beam Techniques

Anion Exchange Membrane Water Electrolyzer (AEMWE) has increased interest in H2 production at low cost and high scalability. The efficiency is strongly dependent on the membrane electrode assembly (MEA) with appropriate ionomer and catalyst layers. Herein, we report AEMWE with MoNi4-MoO2 cathode catalyst layer in ionomer-free Catalyst Coated Substrate (CCS) configuration. The optimized MEA for AEMWE demonstrated the superior performance of 225 mA/cm2 at 2V with more than 48 hours of durability. The X-ray diffraction confirmed the NiMoO4 phase transformation to MoNi4-MoO2 and SEM-EDS was used to study the morphology and elemental composition of the deposited catalyst. X-ray photoelectron Spectroscopy demonstrated the dominant metallic MoO2 formed after H2/Ar annealing. Rutherford Backscattering Spectroscopy (RBS) was also employed to measure the depth composition profile of the catalyst layer exhibiting the reduction of Ni concentration in the bulk after annealing. Further, we introduce hydrogen depth profiling by Nuclear Reaction Analysis (NRA) via the resonant 1H(15N,αγ)12C reaction as a versatile method for the highly depth-resolved visualization of hydrogen(H) in the near-surface region, including transitions of hydrogen between the surface and the bulk, and between shallow interfaces of the nanostructured cathode catalyst layer. The diffusion of the H atoms was observed with a 40% atomic percent of Hydrogen after H2/Ar annealing of the catalyst for 180 minutes (about 3 hours) and decreased to 10% atomic percent of hydrogen after 24 hours of electrolyzer operation. This technique also enabled the measurement of the zero-point vibrational energy of hydrogen atoms absorbed on the surfaces of the catalyst layer. Overall, this work better explains the cathode catalyst degradation effects and hydrogen diffusion in the cathode catalyst layer responsible for voltage and mass transfer losses in AEM electrolyzers.

Hydrogen trapping behavior in IVB-VB transition metal carbides

The hydrogen capture mechanism of transition metal carbides is crucial to improve the hydrogen embrittlement resistance of steel materials. Although numerous experimental and theoretical studies have been carried out, the mechanism of hydrogen capture in these carbides has not been fully elucidated. In this paper, the ability of transition metal carbides (TMCs; TM=Ti, Zr, Hf, V, Nb and Ta) to capture hydrogen is studied by first-principles calculations. It is found that there is a strong correlation between the hydrogen solubility energy and the number of valence electrons of IV-VB transition metal carbides. With the increase of the number of valence electrons, the hydrogen solubility energy decreases, which indicates that IVB transition metal carbides have strong hydrogen capture ability. Compared with interstitial sites, the mechanism by which carbon vacancies are more stable hydrogen capture sites is to enhance the capture stability of hydrogen atoms by reducing the effect of chemical and mechanical effects on the dissolution energy of hydrogen atoms. In the interstitial site, hydrogen atoms tend to occupy the triangular site (TMCs-TM) surrounded by three transition metal atoms and one carbon atom. The bonding interaction between the hydrogen atom and the nearest carbon atom is the main factor affecting the stability of hydrogen atom capture.

Synergistic catalytic effect of LPSO structure and nano (Ni-TiO2)@C on hydrogen storage properties of Mg-Ni-Y alloy

Fine multiphase structure and LPSO structure are formed in the hydrogen storage alloy Mg88.7Ni6.3Y5 by microalloying with small amounts of Ni and Y elements. The catalyst (Ni-TiO2)@C is torn as a carbon layer encapsulating on the surface of the alloy particles by ball milling to form Mg88.7Ni6.3Y5+1 wt.% (Ni-TiO2)@C hydrogen storage composites. The Ni and TiO2 in the catalyst accelerate the dissociation of hydrogen molecules. The carbon carrier prevents the agglomeration of nanocatalysts Ni and TiO2. The alloy exhibited exceptional hydrogen ab/desorption kinetics. It can reach 80% hydrogen absorption saturation content within 1 min. The initial hydrogen desorption temperature has been reduced to 200 °C, and the dehydrogenation content is 4.26 wt.% at 250 °C. The adsorption energies of hydrogen atoms at different sites are calculated by Density Functional Theory (DFT). Synergistic catalytic effects were observed in LPSO and (Ni-TiO2)@C.

Сутегі атомының байланысқан күйлерінің қозу процесін зерттеу

One of the most important areas of plasma physics is the physics of elementary processes, that is, the physics of processes occurring during collisions of molecules, atoms, ions, electrons and photons. The composition of plasma, its thermodynamic, transport, optical and other properties are determined by the processes occurring in the plasma system, as well as their speeds. For this reason, by analyzing collision processes, it is possible to investigate certain properties of the plasma. Traditionally, the study of elementary processes within a specific model begins with the study of the scattering cross section, when the first estimates are made using simple methods. These methods include the Born method, which can and should be applied in practice.In this work, studies were carried out of the influence of collective effects in plasma on the states and energies of hydrogen atoms and hydrogen-like ions, as well as on excitation processes. Quantum mechanics methods were used in the research process, including the variational method and the perturbation theory, especially the Born approximation for inelastic scattering processes. As a result of the work, data were obtained based on the Born approximation for the process of excitation of a hydrogen atom by electron impact. The Born approximation shows better results in the case of high-energy collisions. The results obtained during the study have scientific and experimental significance, since they make it possible to determine the velocity coefficients through the calculation of scattering cross sections. These coefficients, in turn, are necessary to solve the kinetic equation used to describe the sedimentation (concentration) of particles in the plasma.

Growing sp2 materials on transition metals: calculated atomic adsorption energies of hydrogen, boron, carbon, nitrogen, and oxygen atoms, C2 and BN dimers, C6 and (BN)3 hexamers, graphene and h-BN with and without atomic vacancies.

The growth of graphene and hexagonal boron nitride on hot transition metal surfaces involves the adsorption of precursor molecules, and their dissociation and assembly into two-dimensional honeycomb lattices. In a recent account it was found that h-BN may be distilled on a rhodium metal surface, which yields higher quality h-BN [Cun et al., ACS Nano, 2020, 15, 1351]. In this context, we calculated in a systematic approach the adsorption energies and sites of hydrogen, boron, carbon, nitrogen, and oxygen atoms and from the site dependence the activation energy for diffusion. Existing computed values of the solvation energy into the bulk were compared to the present ones with our calculation scheme and found to be in good agreement. For the distinction of different systems we introduce the concepts of epiphilicity and epiphobicity. The adsorption energies and stabilities of the C2 and BN dimers, the C6 and (BN)3 ring-hexamers and the graphene and h-BN monolayers allow the prediction of the performance of different substrates in chemical vapor deposition (CVD) processes for the growth of graphene and h-BN. Finally, vacancy creation energies were calculated as a criterion for the stability of graphene and h-BN on metallic substrates.

Diffusion of hydrogen in the Volterra elastic fields around dislocations in α-Ti: Coupling DFT calculations and elasticity method

Hydrogen around dislocation has a great influence on the mechanical properties of Titanium (Ti) alloys. In this study, the diffusion of hydrogen around dislocations in α-Ti alloys is investigated by coupling density functional theory (DFT) calculations and the elasticity method. Initially, the attempt frequency and hopping activation energy of hydrogen atom in the α-Ti lattice are calculated using the DFT method under various simple strain fields, including volume strain, biaxial strain, and shear strains, within a strain range of −2%–2 %. It is observed that both volume strain and biaxial strain have the most pronounced effects on the hopping activation energy of hydrogen atom, while the attempt frequency remains relatively unaffected across different strain conditions. Subsequently, the hopping activation energy in the elastic strain field has been parameterized using an elasticity method based on elastic dipole and diaelastic polarizability. Using the elasticity method, an analysis is conducted on the effective activation energy of hydrogen atoms and their hopping tendencies in the Volterra elastic strain fields around the perfect edge and screw dislocations. The elastic strain field around screw dislocation enhances the diffusion of hydrogen atoms and simultaneously promotes their migration toward the dislocation core. In the vicinity of edge dislocation, the tensile elastic strain field enhances the diffusion of hydrogen atoms and facilitates their migration toward the dislocation core. Conversely, the compressive strain field retards the diffusion of hydrogen atoms and promotes their migration away from the dislocation core or towards regions with tensile strain.

Interaction of 1/2〈111〉 interstitial dislocation loop with hydrogen and helium in tungsten: molecular dynamics simulation

The interaction of hydrogen and helium atoms with 1/2 〈111〉 interstitial dislocation loop in tungsten is investigated by molecular dynamics simulation. The binding energies of hydrogen and helium atoms around dislocation loop are calculated by molecular statics method. The results show that the outer region of the loop is attractive to the two atoms and the inner region is repulsive. Notably, the maximum binding energies are located in the core region of the dislocation loop. We have also studied the influence factors of the interaction between the dislocation loop and two atoms: free volume, lattice distortion degree, the radius and shape of the dislocation loop. The results show that large free volume benefits the retention of hydrogen and helium atoms, especially for helium. The less lattice distortion caused by the impurity atom, the more favorable for the dislocation loop to trap it. In addition, the larger dislocation loop with higher defect concentration results in stronger capture ability for the hydrogen and helium atoms. The different dislocation loop shapes lead to different binding energy distribution patterns. And the hydrogen and helium atoms tend to occupy the groove region of the concave dislocation loop. Finally, we employ the nudged elastic band theory and dynamics method to investigate the diffusion pattern of the hydrogen atom in the dislocation loop and find that the hydrogen atom tends to migrate spirally around dislocation line. Based on the obtained results, a reasonable interpretation of the interaction behaviors between the dislocation loop with hydrogen and helium atoms are discussed, which can provide essential parameters for mesoscopic scale simulations.

Photoionization Cross Section for H@Cn${\text{H@C}}_{n}$ Implanted in Nonideal Classical Plasmas

AbstractIn this study, photoionization cross sections of guest hydrogen atom in endohedral fullerene () modeled by the Woods–Saxon confinement potential implanted in the nonideal classical plasma (NICP) under spherical confinement are reported for the first time in the related literature. The relevant wave equation is solved numerically via the tridiagonal matrix method and then the energy levels, bound and continuum wave functions are interpreted. Plasma effect is examined by considering plasma temperature and density and is evaluated in the photoionization process. Since the plasma modifies the discrete and continuum spectra by changing the potential energy of hydrogen atom, it closely affects the overlapping of the wave functions of ground state and continuum state. This effect has a distinct response on photoionization resonances. Using different values of endohedral confinement parameters, which means regarding different types of fullerenes, detailed analysis of energy levels, bound and continuum wave functions, and photoionization cross sections are provided by evaluating confinement width, depth, smoothing effect and distance from the spherical encompassement center. The photoionization process of implanted in the NICP (nonideal classical plasma) is highly sensitive to both plasma and endohedral confinement. At this sensitivity, Cooper resonance character is like an encoder for fullerene structure.

Estimation of Correction of Ground State Energy of Hydrogen Atom in Presence of Quadratic GUP

Abstract: String Theory, Quantum Geometry, Loop Quantum Gravity and Black Hole physic all predict the existence of a observable minimal length at Planck scale. For example, in case of string theory it is conjectured that a particle described as a string does not interact at distances smaller than its size. As a consequence, the HUP has to be generalized to take into account this aspect. The models which are designed to implement the minimal length scale and/or the maximum momentum in different physical systems entered into the literature as the Generalized Uncertainty Principle (GUP). Here, quadratic GUP model has been used to estimate the quantum-gravitational correction of ground state energy of hydrogen atom (H-atom).

Hydrogen Promotes the Growth of Platinum Pyramidal Nanocrystals by Size-Dependent Symmetry Breaking.

The growth of pyramidal platinum nanocrystals is studied by a combination of synthesis/characterization experiments and density functional theory calculations. It is shown that the growth of pyramidal shapes is due to a peculiar type of symmetry breaking, which is caused by the adsorption of hydrogen on the growing nanocrystals. Specifically, the growth of pyramidal shapes is attributed to the size-dependent adsorption energies of hydrogen atoms on {100} facets, whose growth is hindered only if they are sufficiently large. The crucial role of hydrogen adsorption is further confirmed by the absence of pyramidal nanocrystals in experiments where the reduction process does not involve hydrogen.

In Situ Generation of Pt2Co3 Nano‐Alloys in Porous N‐Doped Carbon for Highly Efficient Electrocatalytic Hydrogen Evolution

AbstractPlatinum (Pt) catalysts are the state‐of‐the‐art electrocatalysts for hydrogen evolution reaction (HER), but it is still a challenge to improve the utilization efficiency and stability of Pt‐based catalysts. Herein, Pt2Co3 nano‐alloys anchored on the surface of the N‐doped carbon support are precisely synthesized via metal complex‐controlled pyrolysis. Benefiting from the formation and exposure of the bimetallic nano‐alloys, the optimal Pt2Co3/NC‐950 electrocatalyst exhibits an extraordinary HER catalytic activity and stability. To achieve a current density of 10 mA cm−2, the Pt2Co3/NC‐950 electrocatalyst requires small overpotentials of 12 mV in both acidic and alkaline media with small Tafel slopes of 6 mV dec−1 and 24 mV dec−1 in 0.5 M H2SO4 and 1 M KOH, respectively, which is superior to the commercialized Pt/C catalyst. Additionally, the much higher turnover frequencies and the larger electrochemical surface areas of Pt2Co3/NC‐950 further reveal its superior catalytic active sites. Based on theoretical calculations, the outstanding HER activity is found to be attributed to the synergic effect of the Pt and Co components that optimizes the adsorption Gibbs free energy of hydrogen atom and accelerates water dissociation in alkaline media.

Discussion on the Problems of Bohr’s Hydrogen Atom Theory in Basic Theory

According to the charge momentum and charge kinetic energy, it is proved that the key problem of the basic theory of Bohr hydrogen atom is that equation does not hold. For the same electron of the hydrogen atom, the left side of the equation is the mechanical kinetic energy, the right side of the equation is the charge energy, the fundamental properties and the concept of energy are split. Based on experiments, this paper analyzes and calculates the combined energy of hydrogen, lithium and oxygen atoms, hydrogen atom radius and the ground state energy of hydrogen atom are obtained. This ground state energy is basically consistent with the Balmer system of hydrogen atomic spectrum ; Electron around the nuclear velocity . hydrogen atom radius is calculated by using energy , which verifies the correctness of charge momentum and charge kinetic energy and their experimental basis. The ground state energy atom and radius of Bohr hydrogen is derived under the condition that the basic theory has problems and the theoretical formula is set to , which has no experimental basis. The fundamental problem of quantum mechanics is that the theoretical formula of photoelectric effect is not correct, which is demonstrated in this paper. The relationship between the structure of hydrogen atom and the evolution of the universe is also discussed.

Thermal and atomic properties of hydrogen atom and diatomic molecules in Wilson-Racah Quantum System

In this study, a conventional quantum mechanics in which the potential function is not specified but replaced by specifying four parameters Wilson-Racah orthogonal polynomials in the energy and physical parameter space was presented. The wave function is written as a bounded sum of elements of a complete basis with these polynomials as expansion coefficients. By finding the asymptotic of these Wilson – Racah polynomials, the physical properties of the corresponding system (wave function, bound state energy spectrum and/or scattering phase shift) was obtained. Wilson – Racah quantum system was applied to determine the thermodynamics and atomic properties of Hydrogen atom and diatomic molecules. All properties of associated physical systems are obtained directly and simply from the asymptotic of the associated orthogonal polynomials. This new model, gives good an approximate prediction of the Hydrogen atom energy with an estimated average error of 0.125%. The proposed procedure merely relies on experimental values of five molecular constants. The average relative percentage deviations of the thermodynamic properties’ functions Q, U, C, S and F which are 2.42, 0.45, 0.30, 1.23 and 1.50% satisfied the experimental finding as ascertained. These represent satisfactory compromise between accuracy and rapid computations.

Coulomb-Zeeman-Stark problem in two dimensions

Coulomb-bound systems in reduced dimensions are sensitive probes of increased confinement. For example, the ground-state binding energy of hydrogen atoms increases by a factor of 4 when passing from three to two dimensions. Recently, quasi--two-dimensional hydrogen has been realized experimentally in the form of low-dimensional excitons. Their sensitivity to external electric and magnetic perturbations is reduced by the confinement. To quantify the reduction, we consider in the present work two-dimensional hydrogen in crossed electric and magnetic fields. We compare analytical, numerical, and variational results for the binding energy and dipole polarizability in arbitrary magnetic fields. Our analytical expressions for both weak and strong magnetic fields are supplemented by accurate variational and hypergeometric resummation results, thereby covering arbitrary magnetic fields.

Competing Nuclear Quantum Effects and Hydrogen-Bond Jumps in Hydrated Kaolinite.

Recent work has shown that the dynamics of hydrogen bonds in pure clays are affected by nuclear quantum fluctuations, with different effects for the hydrogen bonds holding different layers of the clay together and for those within the same layer. At the clay-water interface there is an even wider range of types of hydrogen bond, suggesting that the quantum effects may be yet more varied. We apply classical and thermostated ring polymer molecular dynamics simulations to show that nuclear quantum effects accelerate hydrogen-bond dynamics to varying degrees. By interpreting the results in terms of the extended jump model of hydrogen-bond switching, we can understand the origins of these effects in terms of changes in the quantum kinetic energy of hydrogen atoms during an exchange. We also show that the extended jump mechanism is applicable not only to the hydrogen bonds involving water, but also those internal to the clay.

Still learning about space dimensionality: From the description of hydrogen atom by a generalized wave equation for dimensions D ≥ 3

A hydrogen atom is supposed to be described by a generalization of the Schrödinger equation, in which the Hamiltonian depends on an iterated Laplacian and a Coulomb-like potential r−β. Starting from previously obtained solutions for this equation using the 1/N expansion method, it is shown that new light can be shed on the problem of understanding the dimensionality of the world as proposed by Paul Ehrenfest. A surprising new result is obtained. Indeed, for the first time, we can understand that not only the sign of the energy but also the value of the ground state energy of hydrogen atoms is related to the threefold nature of space.

First principles study of V/Pd interface interactions and their hydrogen absorption properties

Hydrogen permeation through vanadium/palladium (V/Pd) metal composite membranes is an effective and practical method of separating hydrogen from gas mixtures. In order to gain an insight into the relation between the interfacial structure and hydrogen adsorption/diffusion properties of the catalytic Pd layer bonded to the metal membrane, and then improve the ability of the alloy membrane to purify hydrogen, the first principle based on the density functional theory is used to study the hydrogen adsorption/diffusion behavior at the V/Pd metal composite membrane interface. The results show that because the charge density at the V/Pd interface increases with the V/Pd bonding increasing, the dissolution energy of hydrogen atom (H) increases with it approaching to the interface, and it has the highest dissolution energy near the V/Pd interface (0.567 eV). Hydrogen migration energy barrier calculations show that compared with the maximum energy barrier for horizontal diffusion of H along the V/Pd interface (0.64 eV), the H vertical V/Pd interface energy barrier (0.56 eV) is small, thus H tends to migrate vertically V/Pd interface and diffuse from the Pd layer to the V substrate side. As the hydrogen solvation energy of the Pd layer at the V/Pd interface (0.238 eV) is higher than that on the V membrane side (–0.165 eV), H will gather on the V film side of the interface, which is easy to cause hydrogen to be embrittled. Calculations of Pd/Fe doping of the V matrix show that comparing with the undoped energy barrier (0.56 eV), Pd/Fe doping can significantly reduce the maximum energy barrier (0.45 eV/0.54 eV) in the diffusion path of the interface, which is favorable for hydrogen permeation and diffusion. And the doped interface can inhibit the interdiffusion of V layer and catalytic Pd layer to a certain extent, which improves the structural stability of the composite film.

Hollow NiCoP Nanoprisms Derived from Prussian Blue Analogues as Bifunctional Electrocatalysts for Urea-Assisted Hydrogen Production in Alkaline Media.

Integrating the hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) is an energy-saving approach for electrolytic H2 production. Here, hollow NiCoP nanoprisms are derived from Prussian blue analogues by a combined self-template coordination reaction and gas-phase phosphorization strategy. Benefiting from the strong electron interaction, unique hollow nanostructure, and enhanced mass/charge transfer, NiCoP nanoprisms display outstanding alkaline HER and UOR performance. Specifically, low potentials of -0.052, -0.115, and -0.159V for HER and ultralow potentials of 1.30, 1.36, and 1.42V for UOR at current densities of 10, 50, and 100mA cm-2 are obtained. Moreover, in a urea-assisted water electrolysis system, NiCoP nanoprisms only require cell voltages of 1.36, 1.49, and 1.57V to offer current densities of 10, 50, and 100mA cm-2 , about 170, 180, and 200mV less than the traditional water electrolysis. Theoretical calculations indicate the Co substitution in Ni2 P promotes the adsorption and dissociation of water molecules, optimizes the desorption energy of active hydrogen atoms, and enhances the adsorption of urea molecules, thus accelerating the kinetics of HER and UOR. This work facilitates the application of hollow bimetallic phosphides in electrochemical preparation of clean energy and provides a successful paradigm for urea-rich wastewater electrolysis.

Enhancing hydrogen evolution reaction by synergistically coupling NiMo alloy with Mo on Ni foam

The large-scale preparation of non-precious-metal hydrogen evolution reaction (HER) electrodes with remarkable performance was important to the energy crisis. Here, Mo-NiMo/NF (Ni Foam) electrodes were fabricated by homemade high power impulse magnetron sputtering technique with subsequent annealing. The synthesized Mo-NiMo/NF electrodes presented an exceptional electrocatalytic performance with η10 = 71 mV and prominent stability in alkaline aqueous electrolyte for the HER. The experimental data were corroborated by density functional theory (DFT) calculations. The significant catalytic performance for HER active arose from NiMo alloy and the coupling effect between Mo and NiMo alloy. The lowest value on Gibbs free energy of NiMo was − 0.027 eV, very close to the ideal value zero. The adsorption energy of hydrogen atom from heterojunction between Mo and NiMo was − 1.786 eV, which could facilitate Volmer step to further enhance HER activity. More importantly, this synthesis method reported here was scalable, which could provide a valuable strategy to engineer the electrocatalysts with the aim to improve their catalytic activities.