Hydrogen Energetics Research Articles

HTGR – New Prospects for Nuclear Energy

High-temperature gas-cooled reactors (HTGR) are a new type of environmentally clean source of nuclear energy. Their unique properties – capability of generating heat at temperatures to 1000°C and a high safety security – determine the wide possibilities for using reactors of this type to produce hydrogen from water, supply heat for technological processes in different industries, and produce electricity very efficiently in a gas-turbine cycle. Currently, OKBM Afrikantov is working jointly with Russian enterprises on the development of a nuclear power plant + hydrogen energy plant (NPP-HEP) with HTGR and a chemical-technology part for hydrogen production. This work should result in a decision on the construction of the lead block of NPP-HEP with HTGR and a chemical technological part for hydrogen production. The implementation of this project will contribute to the solution of the global problems of decarbonization and growing consumption of energy and it will stimulate the formation of a new technological order – hydrogen energetics.

Charge transfer controlled hydrogenation of graphene on an electronically modified Pt(111) surface

The interfaces of graphene and hydrogenated graphene with 3d atom embedded Pt(111) [Pt-3d-Pt(111), 3d: Fe, Co] substrates have comparatively been investigated utilizing X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and temperature-programmed XPS (TPXPS) and desorption (TPD). 3d atoms in the subsurface layer of Pt(111) change the electronic properties of graphene via modifying its p-doping level. Hydrogenation makes graphene pinned to the Pt(111) and Pt-3d-Pt(111) substrates and induces surface segregation of 3d atoms from the subsurface layer into the interface of HGr and Pt-3d-Pt(111). Such a mechanism changes the desorption energetics of hydrogen significantly.

Structure and energetics of microscopically inhomogeneous nanoplasmas in exploding clusters

Abstract We present a theoretical-computational study of the formation, structure, composition, energetics, dynamics and expansion of nanoplasmas consisting of high-energy matter on the nanoscale of ions and electrons. Molecular dynamics simulations explored the structure and energetics of hydrogen and neon persistent nanoplasmas formed under the condition of incomplete outer ionization by the laser field. We observed a marked microscopic inhomogeneity of the structure and the charge distribution of exploding nanoplasmas on the nanoscale. This is characterized by a nearly neutral, uniform, interior domain observed for the first time, and a highly positively charged, exterior domain, with these two domains being separated by a transition domain. We established the universality of the general features of the shape of the charge distribution, as well as of the energetics and dynamics of individual ions in expanding persistent nanoplasmas containing different positive ions. The inhomogeneous three-domain shell structure of exploding nanoplasmas exerts major effects on the local ion energies, which are larger by one order of magnitude in the exterior, electron-depleted domain than in the interior, electron-rich domain, with the major contribution to the ion energies originating from electrostatic interactions. The radial structural inhomogeneity of exploding nanoplasmas bears analogy to the inhomogeneous transport regime in expanded and supercritical metals undergoing metal-nonmetal transition.

Superprotonics: New Materials for Energy-Efficient Technologies

One of the most rapidly developing directions in the field of alternative energy sources is hydrogen energetics. Fuel cells, the main component of which is a proton-exchange membrane, facilitate the direct conversion of chemical energy into electrical energy. Superprotonic crystals are promising materials for the creation of proton-exchange membranes of fuel cells and other electrochemical. Multicomponent water–salt growth systems are studied in order to obtain new superprotonic crystals MmHn(AO4)(m + n)/2 ⋅ yH2O (M = K, Rb, Cs, NH4, AO4 = SO4, SeO4, HPO4) and modify the properties of known compounds. The conditions for the growth of a number of new superprotonics are found, and the relationships between their structure and properties are studied.

Suppression of hysteresis in absorption of hydrogen by a Pd-Au alloy.

Hydrogen absorption by Pd exhibits hysteresis loops (provided the temperature is not too high) and represents one of the classical examples of first-order phase transitions in metals. Experiments indicate that addition of even a small amount of Au is able to suppress hysteresis. From this perspective, we analyze the energetics of hydrogen in a Pd-Au alloy by using extensive density-functional-theory (DFT) calculations. The dependence of the hydrogen binding energy on the number (n) of Au atoms forming an adsorption site is found to be appreciably nonlinear. With the DFT input for statistical calculations, we reproduce special features of the hydrogen absorption isotherms and explain the rapid decrease of the corresponding critical temperature with increasing Au fraction. The key factor here is that the phase transition is related primarily to absorption in sites formed only by Pd. With increasing Au amount, the fraction of such sites rapidly decreases, the distance between H atoms located there becomes on average larger, the interaction between them becomes weaker, and accordingly the driving force for the phase transition decreases. It is of interest that all these effects can be illustrated by taking only the configurations with n≤2 into account. This means that in the context under consideration the fine details of the dependence of the hydrogen binding energy on n are in fact not too important.

The Role of Support in Formic Acid Decomposition on Gold Catalysts

Formic acid (FA) can easily be decomposed, affording molecular hydrogen through a controllable catalytic process, thus attaining great importance as a convenient hydrogen carrier for hydrogen energetics. Supported gold nanoparticles are considered to be among the most promising catalysts for such applications. However, questions remain regarding the influence of the catalyst support on the reaction selectivity. In this study, we have examined the catalytic activity of typical gold catalysts, such as Au/TiO2, Au/SiO2, and Au/Al2O3 in decomposition of FA, and then compared it with the catalytic activity of corresponding supports. The performance of each catalyst and support was evaluated using a gas-flow packed-bed reactor. It is shown that the target reaction, FA → H2 + CO2, is provided by the presence of gold nanoparticles, whereas the concurrent, undesirable pathway, such as FA → H2O + CO, results exclusively from the acid-base behavior of supports.

Analysis of maximum braking power for determination of energy storage device characteristics within fuel cell electric bus

The article describes development of hydrogen energetics over the 2014 to 2018 period. There are statistic data about significant influence of hydrogen vehicles on that energy sector. The development of this means of transport is funded by the governments in different countries and that means big prospects for that technology. Modern researches especially are targeted at optimal approach searching to drive the electrochemical generator (fuel cell) as an initial energy source in the united energy plant. The offered approach is based on the movement characteristics data which were obtained from operated on the real city route trolleybus. The preference is given to use the experimental data for further synthesis of the city fuel cell bus model.

ИСПОЛЬЗОВАНИЕ РЕАКТОРА ТИПА ВТГР ДЛЯ ПРОИЗВОДСТВА ВОДОРОДА - ШАГ К «ЗЕЛЕНОЙ» ЭНЕРГЕТИКЕ БУДУЩЕГО

Hydrogen energetics is an alternative energy industry based on the use of hydrogen as a means of accumulating, transporting and consuming energy. Of the innovative nuclear energy sources proposed by the INPRO or G-4 programs, only reactors with a helium coolant are capable of providing a sufficient heat supply temperature to the hydrogen production units. Reactors of this type based on microfuel have fundamental safety advantages associated with the absence of core melting in case of accidents with loss of coolant. This article presents an overview of the technology of using high-temperature gas-cooled reactors and its features. The results of a computational analysis of an energy complex with a nuclear power plant of the HTGR type with a thermal power of 600 MW and energy conversion modules with gas turbine or steam turbine and thermochemical production of hydrogen by steam reforming of methane or high-temperature electrolysis is considered in the article. The fuel of the nuclear reactor under consideration consists of mixed oxides of plutonium and thorium. The calculation method involves the use of a one-dimensional GETERA code for calculating the diffusion coefficients and group cross-sections and the COMSOL Multiphysics software package for calculating the neutron-physical characteristics in the three-group diffusion approximation by the finite element method and comparison with the results obtained by the Monte Carlo method using MCU precision program.

Hydrogen on Cobalt Phosphide.

Cobalt phosphide (CoP) is one of the most promising earth-abundant replacements for noble metal catalysts for the hydrogen evolution reaction (HER). Critical to HER is the binding of H atoms. While theoretical studies have computed preferred sites and energetics of hydrogen bound to transition metal phosphide surfaces, direct experimental studies are scarce. Herein, we describe measurements of stoichiometry and thermochemistry for hydrogen bound to CoP. We studied both mesoscale CoP particles, exhibiting phosphide surfaces after an acidic pretreatment, and colloidal CoP nanoparticles. Treatment with H2 introduced large amounts of reactive hydrogen to CoP, ca. 0.2 H per CoP unit, and on the order of one H per Co or P surface atom. This was quantified using alkyne hydrogenation and H-atom transfer reactions with phenoxy radicals. Reactive H atoms were even present on the as-prepared materials. On the basis of the reactivity of CoP with various molecular hydrogen donating and accepting reagents, the distribution of binding free energies for H atoms on CoP was estimated to be roughly 51-66 kcal mol-1 (ΔG°H ≅ 0 to -0.7 eV vs H2). Operando X-ray absorption spectroscopy gave preliminary indications about the structure of hydrogenated CoP, showing a slight lattice expansion and no significant change of the effective nuclear charge of Co under H2-flow. These results provide a new picture of catalytically active CoP, with a substantial amount of reactive H atoms. This is likely of fundamental relevance for its catalytic and electrocatalytic properties. Additionally, the approach developed here provides a roadmap to examine hydrogen on other materials.

Reaction energetics of hydrogen on Si(100) surface: A periodic many-electron theory study.

We report on a many-electron wavefunction theory study for the reaction energetics of hydrogen dissociation on the Si(100) surface. We demonstrate that quantum chemical wavefunction based methods using periodic boundary conditions can predict chemically accurate results for the activation barrier and the chemisorption energy in agreement with experimental findings. These highly accurate results for the reaction energetics enable a deeper understanding of the underlying physical mechanism and make it possible to benchmark widely used density functional theory methods.

Effect of interatomic potential on the energetics of hydrogen and helium-vacancy complexes in bulk, or near surfaces of tungsten

Hydrogen (H) trapping by helium-vacancy (HeV) complexes in bulk and the near surface region of tungsten (W) have been investigated by molecular statics calculations that evaluate two different WH interatomic potentials, which use the same WHe, HeHe and HeH potentials. One of the WH potentials is a bond-order potential (BOP) developed by Juslin et al., while the other is an embedding atom method (EAM) potential developed by Wang et al.. Both potentials overestimate the H binding energies to He clusters in bulk W, as compared to DFT calculations, but properly predict the functional form of the H binding energies to He clusters with increasing number of He and H. The BOP simulations reveal that H binding energies to HexV complexes generally increase with increasing number of He. However, the EAM results indicate that the H binding energy as a function of number of He depends on the number of H, and the H binding energies change slightly at high He content. Compared with available DFT data, both BOP and EAM underestimate the H binding energies to HexV2Hm complexes. The BOP reproduces the He formation energy below a W surface, while the EAM potential better reproduces the H formation energy and the interactions between H and HeV complexes. Based on these comparisons, we determine that the EAM potential is more accurate than BOP for large-scale molecular dynamics simulations of WHeH interactions. The EAM potential predicts that the difference in the average binding energies of H to stable HeV complexes near the W surface is less than 0.2 eV and the difference decreases with increasing He content. Thus, the EAM potential indicates that the effect of surfaces on H binding energies to large HeV complexes below the W surfaces can be ignored.

Beyond the random phase approximation with a local exchange vertex

With the aim of constructing an electronic structure approach that systematically goes beyond the GW and random phase approximation (RPA) we introduce a vertex correction based on the exact-exchange (EXX) potential of time-dependent density functional theory. The EXX vertex function is constrained to be local but is expected to capture similar physics as the Hartree-Fock vertex. With the EXX vertex we then consistently unify different beyond-RPA approaches such as the various re-summations of RPA with exchange (RPAx) and the second order screened exchange (SOSEX) approximation. The theoretical analysis is supported by numerical studies on the hydrogen dimer and the electron gas, and we discuss the importance of including the vertex correction in both the screened interaction and the self energy. Finally, we give details on our implementation within the plane-wave pseudo potential framework and demonstrate the excellent performance of the different RPAx methods in describing the energetics of hydrogen and van der Waals bonds.

Composite Materials with 2D Graphene Structures: Applications for Hydrogen Energetics and Catalysis with Hydrogen Participation

The work presents the results of studies concerning preparation of graphene-like nanomaterials by graphite oxide reduction, preparation of nickel-graphene catalysts, magnesium-graphene, and carbon-graphene composites. Optimum conditions for preparing these materials and their functional characteristics are determined.

Energetics of hydrogen and helium-vacancy complexes in bulk and near surfaces of tungsten: First-principles study

Understanding the interaction between hydrogen (H) and helium-vacancy (He-V) complexes in tungsten (W) is important for the development of plasma-facing materials in fusion reactors. H trapping by HexVy complexes in bulk W, as well as the H solution behavior and H trapping by HexV complexes near W(100), W(111), and W(110) surfaces, has been investigated by first-principles computer simulations using density function theory. The results show that the sequential H binding energies to HexV complexes in bulk W decrease with the increasing number of H and He. For the HexV2 complexes in bulk W, H prefers to trap at interstitial sites near the junction of the di-vacancy, where the H can minimize the isosurface of optimal charge density. The most stable interstitial sites for H below W surfaces are dependent on the surface orientation. Our calculations indicate that H atoms tend to prefer a depth of 0.3 nm below the W(100) and W(111) surfaces due to the surface reconstruction. The binding energy of H to a HeV complex near W surfaces has the most significant orientation dependence below the W(111) surface, followed by the W(100) and W(110) surfaces. Compared with the bulk value, the largest difference in the average binding energy of H to the stable HexV complexes at the three W surfaces is about 0.2 eV. Furthermore, the effect of surfaces on the H binding energy to HexV complexes can be ignored for depths greater than 0.65 nm.

Композиты с 2D-графеновыми структурами для водородной энергетики и катализа процессов с участием водорода

Композиты с 2D-графеновыми структурами для водородной энергетики и катализа процессов с участием водорода

Nanostructured carbon materials for hydrogen energetics

Nanostructured carbon materials for hydrogen energetics

Addressing first derivative discontinuities in orbital-optimised opposite-spin scaled second-order perturbation theory with regularisation

ABSTRACTOrbital-optimised opposite-spin scaled second-order perturbation theory (O2) generates a single-reference wave function composed of approximate Brueckner orbitals with fourth-order computational scaling. While O2 provides significantly improved treatment of radicals by reducing spin contamination, it has been shown to suffer from first derivative discontinuities for bond stretching near the unrestriction point. That qualitative failure is resolved in this work by the implementation of regularised O2, which includes a regularisation parameter in the denominator of its second-order term. The value of the regularisation parameter is semi-empirically chosen to qualitatively describe bond stretching energetics of hydrogen, ethane and ethene, while also considering the effect of the regularisation parameter on thermochemical errors for the well-known Gaussian-2 (G2) test set. The generality of the empirical scaling and semi-empirical regularisation parameter is studied by application to the 3dMLBE20, DBH24, RSE43 and W4-11 test sets. We demonstrate that accuracy of O2 is roughly maintained and sometimes even improved by regularisation, with root mean squares of regularised O2 between factors of 1.6 and 0.8 from corresponding root mean squares of O2.

Reaction kinetics of hydrogen abstraction from polycyclic aromatic hydrocarbons by H atoms.

Hydrogen abstraction reactions of polycyclic aromatic hydrocarbons (PAH) by H atoms play a very important role in both PAH and soot formation processes. However, large discrepancies up to a few orders of magnitude exist among the literature rate constant values. To increase the reliability of the computed rate constants, it is critical to obtain highly accurate potential energy surfaces. For this purpose, we have investigated the energetics of hydrogen abstraction from benzene and naphthalene using both high level-of-theory quantum chemistry methods and a series of density functional theory (DFT) methods, among which M06-2X/6-311g(d,p) has the best performance with a mean unsigned deviation from the CCSD(T)/CBS calculations of 1.0 kcal mol-1 for barrier heights and reaction energies. Thus, M06-2X/6-311g(d,p) has then been applied to compute the potential energy surfaces of the hydrogen abstraction reactions of a series of larger PAH. Based on the quantum chemistry calculations, rate constants are computed using the canonical transition state theory. The effects of the PAH size, structure, and reaction site on the energetics and rate constants are examined systematically. Finally, the hydrogen abstraction rate constants for application in PAH and soot surface chemistry models are recommended.

The physical energy of the photons that used wildlife on the Earth can solve basic problems of energy and life outside the Earth

The concept of the new managed Eco-Physical hydrogen Energetics of Photons (EFhEF – energetics) is introduced. It can solve the problems of ecology and of the replacement of fossil fuels on the Earth and is able to meet the challenges of life outside the Earth: lighting and heat, air and water regeneration, and return of all 100% organic waste at the new cycle of use, and even with the production of food from this waste. The EFhEF – energetics inherits the technologies of wildlife (yet photosynthesis) which use energy in the form of separate photons of solar radiation. The photosynthesis only is the way to capture CO2 and of Sun’s energy to ensure of organic structures. The wildlife is managed by the digital software, recorded in the molecule of DNA, and works in conventional terrestrial atmospheric conditions (4-40°C) using the energy of solar photons. For the first time, the EFhEF energetics provided any installation by its own source of energy ("solar" photons). This allows to actually inheriting the rich experience of the wildlife for operation with organic matter. The EFhEF- energetics allows “to carry out” even our Sun at any distance in the space.

Discrete breathers in graphane: Effect of temperature

The discrete breathers in graphane in thermodynamic equilibrium in the temperature range 50–600 K are studied by molecular dynamics simulation. A discrete breather is a hydrogen atom vibrating along the normal to a sheet of graphane at a high amplitude. As was found earlier, the lifetime of a discrete breather at zero temperature corresponds to several tens of thousands of vibrations. The effect of temperature on the decay time of discrete breathers and the probability of their detachment from a sheet of graphane are studied in this work. It is shown that closely spaced breathers can exchange energy with each other at zero temperature. The data obtained suggest that thermally activated discrete breathers can be involved in the dehydrogenation of graphane, which is important for hydrogen energetics.