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The energy targets of the Sustainable Development Goals (SDGs) call for both a reduction of total energy use and an increase in the share of renewables as part of the total consumed energy. With the emergence of Renewable Energy Systems (RES) on a local scale there is still little research on the efficiency of actual micro-grids on building scale, let alone on how their functioning relates to reaching the energy targets of the SDGs. Here it is shown how an expected degree of decrease in renewable energy generation from solar panels, combined with a failure to anticipate intensifying building energy needs, can impede reaching the SDGs’ energy targets on the local level. When examining a building scale micro-grid, not only had solar panel performance decreased by twice the expected average, but building energy use had doubled by 156-203%, and thereby the share of renewable energy of total energy use has decreased by 29-47%, depending on the season. This indicates that in order to reach the SDG energy targets, it is important that newly designed building, as well as community Energy Management Systems, do not merely account for current energy users, but accommodate increasing RES concurrent to increasing energy demand.

Based on the concept of density of states (DOS) engineering, we theoretically designed a pseudo-Tc material (Mo–Ru alloy) and investigated its electronic structure, phase stability and catalytic activity by using density functional theory. Through comparing the DOS shape, peak distribution, and DOS area differences between Tc and the Mo–Ru alloy, we noticed that bcc-Mo8Ru8 and hcp-Mo8Ru8 had the most similar electronic structures to Tc. The excess energies after entropy correction of hcp-Mo8Ru8 and bcc-Mo8Ru8 are stable when the temperature is up to 765 and 745 K, respectively. These results provided the possibility of pseudo-Tc alloy (hcp-Mo8Ru8 and bcc-Mo8Ru8) synthesis. Finally, according to reaction coordinate analysis, the similar catalytic activity between hcp-Mo8Ru8 and Tc have been demonstrated in CO oxidation and N2 dissociation. In N2 dissociation, Tc has a suitable ratio of transition state (TS) barrier to reaction energy which make Tc an efficient catalyst for NH3 synthesis, in addition to our designed pseudo-Tc (hcp-MoRu) because of the similar electronic structures. Our finding provides valuable insight into materials and catalyst design.

The oxidation of carbon monoxide (CO) over PdRu solid solution nanoparticles was studied by the combined theoretical and experimental approaches. In this work, CO and O adsorptions on PdRu alloy surface models were theoretically investigated to understand the kinetics of CO oxidation reaction. It was found that CO adsorption on Pd atom in the PdRu alloy surfaces is weaker than on monometallic surfaces. From the experiment, reaction order of CO on the PdRu surface was observed to be smaller than that on Pd surface. While, the positive first order with respect to O2 obtained for both Pd and PdRu alloy surfaces. Catalytic reaction mechanism is discussed on the basis of both theoretical and experimental observations.

Hybrid materials composed of metal nanoparticles and metal-organic frameworks have attracted attention for various applications because of the synergistic functionality between their constituent materials. Interfacial interaction is expected however the mechanism remains ambiguous. Here we report the valence bands of palladium nanocubes covered by copper(II) 1, 3, 5-benzenetricarboxylate (HKUST-1), denoted as Pd@HKUST-1, and the charge transfer from the palladium nanocubes to HKUST-1 at the Pd/HKUST-1 interface is investigated quantitatively. Interfacial density of states are different from those of internal constituents and imply that the Cu-O group in HKUST-1 acts as a charge accepter. The role of Cu-O group in charge transfer behaviour is also observed experimentally. Finally, we reveal the charge transfer mechanism from the Pd 4d bands to the Cu 3d (4sp) - O 2p hybridization bands of HKUST-1 at the Pd/HKUST-1 interface, which explains the enhanced hydrogen storage capacity in Pd@HKUST-1., Pd-MOFハイブリッド材料の界面電子状態と水素貯蔵特性の関係の定量的な解析に成功 --電子約0.4個分の電荷移動が約2倍の特性向上に寄与 新規ハイブリッド材料開発の促進が期待--. 京都大学プレスリリース. 2018-10-11.

We analyzed theoretically the hydrogen absorption properties and kinetics into Pd nanocubes coated with copper(II) 1,3,5-benzenetricarboxylate (HKUST-1), which is a type of metal–organic framework, using density functional theory. We prepared an interface model consisting of the Pd(100) surface and Cu-edged HKUST-1 structure and calculated the hydrogen adsorption and absorption energies in a Pd nanocube model. To discuss the kinetics of the hydrogen absorption, we also evaluated the hydrogen diffusion barrier near the interface. Compared with bare Pd, the hydrogen diffusion barrier from the surface to the subsurface decreased. We found that the adsorption of HKUST-1 on the Pd nanocube leads to chemical and steric effects for the diffusion rate increase of hydrogen. As a chemical effect, hydrogen adsorption was destabilized by the change of electronic structure of the Pd surface because of the atomic charge displacement between the Pd and Cu atoms in HKUST-1. As a steric effect, a new hydrogen diffusion pa...

Abstract While Pt-nanoparticles supported on SnO2 exhibit improved durability, a substantial detriment is observed on the Pt-nanoparticles’ activity toward the oxygen reduction reaction. A density functional theory method is used to calculate isolated, SnO2- and graphene-supported Pt-nanoparticles. Work function difference between the Pt-nanoparticles and SnO2 leads to electron donation from the nanoparticles to the support, making the outer-shell atoms of the supported nanoparticles more positively charged compared to unsupported nanoparticles. From an electrostatic point of view, nucleophilic species tend to interact more stably with less negatively charged Pt atoms blocking the active sites for the reaction to occur, which can explain the low activity of Pt-nanoparticles supported on SnO2. Introducing oxygen vacancies and Nb dopants on SnO2 decreases the support work function, which not only reduces the charge transferred from the Pt-nanoparticles to the support but also reverses the direction of the electrons flow making the surface Pt atoms more negatively charged. A similar effect is observed when using graphene, which has a lower work function than Pt. Thus, the blocking of the active sites by nucleophilic species decreases, hence increasing the activity. These results provide a clue to improve the activity by modifying the support work function and by selecting a support material with an appropriate work function to control the charge of the nanoparticle’s surface atoms. Graphic abstract

The triple phase boundary (TPB) of metal, oxide, and gas phases in the anode of solid oxide fuel cells plays an important role in determining their performance. Here we explore the TPB structures from two aspects: atomic-resolution microscopy observation and reaction dynamics simulation. Experimentally, two distinct structures are found with different contact angles of metal/oxide interfaces, metal surfaces, and pore opening sizes, which have not previously been adopted in simulations. Reaction dynamics simulations are performed using realistic models for the hydrogen oxidation reaction (HOR) at the TPB, based on extensive development of reactive force field parameters. As a result, the activity of different structures towards HOR is clarified, and a higher activity is obtained on the TPB with smaller pore opening size. Three HOR pathways are identified: two types of hydrogen diffusion processes, and one type of oxygen migration process which is a new pathway. The triple phase boundary structure in solid-oxide fuel cells largely determines the thermodynamics and kinetics of electrochemical processes therein. Here the authors use atomic-resolution microscopy and reaction dynamics simulation to reveal three discrete hydrogen oxidation reaction pathways.

The implementation of energy systems and technologies has been incentivized by the assessment of various aspects, including social and economic acceptance and sharing rational technology targets. In this study, battery-assisted hydrogen production systems were analyzed with regard to their environmental and techno-economic aspects. The costs of hydrogen production were minimized by the capacity optimization of the system components based on different development levels of contained technologies. The cost minimization indicated the upper limit of battery cost for reducing hydrogen cost. The relation with the cost of electrolyzer can be formulated in some assumptions. Greenhouse gas emissions and the abiotic resource depletion of cost-minimized systems were also analyzed. The performance of battery-assisted hydrogen production on unit cost and greenhouse gas emission may be high enough to be competitive with other hydrogen production or fossil fuel use. In contrast, the environmental impact of this system on the abiotic resource depletion is too large to be environmentally competitive to other options. Technology and system improvements such as metal recycling are important factors for the system.

The density of states and the H absorption energy of Ag x Rh 1- x alloys were theoretically investigated by the first-principles method. The electronic structure of the alloys near the Fermi edge was similar to that of Pd, which is known as hydrogen-storage metal, and this indicated the electronic state at the part plays important role to determine the H absorption property. The results showed that the H absorption into the Ag x Rh 1- x alloys was thermodynamically stable and the trend of composition dependence agreed well with the experimental observation. Considering the atomic configuration of alloys, homogeneous structure is found to be a key in the emergence of H absorption nature in this alloy system.

The phase stability of real-system bimetallic Pt3Co, Pt3Ni, and Pt3Cu nanoparticles is investigated by means of density functional theory method and massively parallel computing to understand the Pt3M nanoparticles’ physicochemical properties. The bimetallic nanoparticles with 1-skin Pt layer are more stable than the solid solution and 2-skin Pt layer configurations due to the larger magnitude of the excess energy. For bimetallic nanoparticles with Pt skin layers, the atomic charge and d-band centers of the surface Pt atoms are linearly related to their stability. On the other hand, the stability of the bimetallic nanoparticles with solid solution configurations is linearly related to the surface Pt atoms’ d-band centers and strain. From the multiple regression analysis, the combination of the surface Pt atoms’ charge and strain, and charge and d-band centers can be used to estimate the stability of the bimetallic nanoparticles with Pt skin layers and solid solutions configurations, respectively, while including the size effect. Our results give a clue for tuning the surface properties, stability, and activity by altering the configuration and alloying elements in the bimetallic nanoparticles.

Microgrids comprising renewable energy technologies are often modelled and optimised from a theoretical point of view. Verification of theoretical systems with data of actually implemented systems in the field rarely occurs in an open manner, especially on the intermediate scale of research buildings. To enable modelling of the actual microgrid performance of a research environment, we present a multiyear dataset of a microgrid with solar arrays and a battery. The main energy datasets comprise data per second supplemented by hourly solar irradiation data. These may be combined with data concerning the hourly electricity prices from the main grid and the low-electricity-price periods of national holidays. The level of detail of the data per second in combination with the hourly data in these datasets allows for a comparison to the efficiency and weather-parameter correlation of other renewable energy technologies, as well as forecasting future energy generation and consumption.

Although Ir or Au is not active for ORR, we first demonstrate highly active Au0.5Ir0.5 alloy by emulating Pt LDOS profile., The electronic structure of surface atoms has a great effect on catalytic activity because the binding energy of reactants is closely related to the electronic structure. Therefore, designing and controlling the local density of states (LDOS) of the catalyst surface would be a rational way to develop innovative catalysts. Herein, we first demonstrate a highly active AuIr solid-solution alloy electrocatalyst for the oxygen reduction reaction (ORR) by emulating the Pt LDOS profile. The calculated LDOS of Ir atoms on the Au0.5Ir0.5(111) surface closely resembled that of Pt(111), resulting in suitable oxygen adsorption energy on the alloy surface for the ORR. We successfully synthesized AuIr solid-solution alloys, while Ir and Au are immiscible even above their melting points in the bulk state. Although monometallic Ir or Au is not active for the ORR, the synthesized Au0.5Ir0.5 alloy demonstrated comparable activity to Pt at 0.9 V versus a reversible hydrogen electrode.

We analyzed the X-ray absorption spectra (XAS) of Co 2 p orbital in LaCoO 3 by using density functional theory method to understand the temperature effect on the electronic structures, especially low-spin (LS), intermediate-spin (IS), and high-spin (HS) states of Co 3 + ion. We considered the lattice change, thermal excitation of electrons, and displacement of atoms from equilibrium position in LaCoO 3 as a temperature effect in this study. We observed negligible change in the shape of Co 2 p XAS of LaCoO 3 for each LS, IS, and HS state associated with the lattice expansion due to temperature increase, while different spectral features for LS, IS, and HS states were observed. The change of spectra observed by in situ XAS measurement of LaCoO 3 at Co L II - and L III -edges would be due to the increase in HS and decrease in LS and IS at higher temperature. In addition, the geometry change by thermal displacement of atomic position was analyzed by using first-principles molecular dynamics calculation. Our results indicated that the electronic structure is sensitively changed by the change of Co-O bond distance due to the displacement of atoms from the equilibrium position at studied temperature when the spin state was IS.

The hydrogen absorption energy and the density of states (DOS) are calculated based on the density functional theory to study the effect of alloying elements on the properties of Pd-M solid solution alloys (M = Rh, Pd, Ag, Ir, Pt, Au). The calculated H absorption energy shows a dependence on the identity of the alloying elements and the trend indicates a correlation with experimental result. The calculation results suggest that the local environment surrounding the H atoms strongly affects the H absorption energy. That is, the first nearest-neighbors of the H atom determine the stability of the system and this implies that H absorption capacity of the entire alloys attributes to the atomic-scale configurations. The DOS provides a good explanation of these observations. Hybridization between the nearest-neighbor metals and H shows evidence of the contribution of the local environment. Furthermore, the elemental dependence of the H absorption energy for each alloy is explained by the DOS near the Fermi energy, which is found to influence the stability of H absorption.

Integration of solid oxide fuel cell (SOFC) in coal gasification power plant technology would be one of the most promising technology in the coal utilization for power generation. The clean syngas from gas cleanup unit serves as fuel for SOFC in integrated gasification fuel cell power plant. The heat generated by SOFC can be utilized by heat recovery steam generator to drive steam turbine for electricity production. In this study, proposed plants consisting of coal gasifier and SOFC on the top of a steam turbine (ST), called light integrated gasification fuel cell (L-IGFC), are investigated thermodynamically by using Aspen Plus software to evaluate their performance. The analyses are based on the SOFC module considering ohmic, activation and concentration losses at a certain current density of the cell operating at the intermediate temperature. The influences of gas cleanup unit models were also investigated. The results indicated that the proposed atmospheric L-IGFC plant could achieve electrical efficiency in the range of 39–46.35% in lower heating value.

It is known that the minor elements affect the performance of solid oxide fuel cell (SOFC). In this study, we focus on the influence of minor elements on the SOFC cathode properties. The Ca, Ba, Al, and Si, which originate from raw materials and production processes for SOFC cathodes, are investigated as minor elements that may have effect on the properties of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode. To examine the effects of minor elements on the cathode properties, Ca, Ba, Al, and Si with a controlled concentration are added to the LSCF reference sample. Conductivity relaxation measurements are conducted to determine the chemical diffusion coefficient (Dchem) and surface exchange coefficient (ktr), which governs the overpotential characteristics of the LSCF cathode. The results show that Al and Si have negative effects on both Dchem and ktr while Ca and Ba do not alter Dchem and show weakly positive effects on ktr. The effects of Ca and Ba for the cathode properties are discussed on the basis of XPS measurements.

The design of energy systems has become an issue all over the world. A single optimal system cannot be suggested because the availability of infrastructure and resources and the acceptability of the system should be discussed locally, involving all related stakeholders in the energy system. In particular, researchers and engineers of technologies related to energy systems should be able to perform the forecasting and roadmapping of future energy systems and indicate quantitative results of scenario analyses. We report an energy flow model developed for analysing scenarios of future Japanese energy systems implementing a variety of feasible technology options. The model was modularized and represented as functionals of appropriate technology options, which enables the aggregation and disaggregation of energy systems by defining functionals for single technologies, packages integrating multi-technologies, and mini-systems such as regions implementing industrial symbiosis. Based on the model, the combinations of technologies on both energy supply and demand sides can be addressed considering not only the societal scenarios such as resource prices, economic growth and population change but also the technical scenarios including the development and penetration of energy-related technologies such as distributed solid oxide fuel cells in residential sectors and new-generation vehicles, and the replacement and shift of current technologies such as heat pumps for air conditioning and centralized power generation. The developed model consists of two main modules; namely, a power generation dispatching module for the Japanese electricity grid and a demand-side energy flow module based on a sectorial energy balance table. Both modules are divided and implemented as submodules represented as functionals of supply- and demand-side technology options. Using the developed model, three case studies were performed. Required data were collected through workshops involving researchers and engineers in the energy technology field in Japan. The functionals of technologies were defined on the basis of the availability of data and understanding of the current and future energy systems. Through case studies, it was demonstrated that the potential of energy technologies can be analysed by the developed model considering the mutual relationships of technologies. The contribution of technologies to, e.g., the reduction in greenhouse gas emissions should be carefully examined by quantitative analyses of interdependencies of the technology options.

Michihisa Koyama1,2, Seiichiro Kimura2, Yasunori Kikuchi2,3, Takao Nakagaki4 and Kenshi Itaoka2 1 Inamori Frontier Research Center, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395, Japan 2 International Institute for Carbon-Neutral Energy Research, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi, Fukuoka 819-0395, Japan 3 Presidential Endowed Chair for “Platinum Society,” e University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 4 Department of Modern Mechanical Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan

Rh is one of the most important noble metals for industrial applications. A major fraction of Rh is used as a catalyst for emission control in automotive catalytic converters because of its unparalleled activity toward NOx reduction. However, Rh is a rare and extremely expensive element; thus, the development of Rh alternative composed of abundant elements is desirable. Pd and Ru are located at the right and left of Rh in the periodic table, respectively, nevertheless this combination of elements is immiscible in the bulk state. Here, we report a Pd–Ru solid-solution-alloy nanoparticle (PdxRu1-x NP) catalyst exhibiting better NOx reduction activity than Rh. Theoretical calculations show that the electronic structure of Pd0.5Ru0.5 is similar to that of Rh, indicating that Pd0.5Ru0.5 can be regarded as a pseudo-Rh. Pd0.5Ru0.5 exhibits better activity than natural Rh, which implies promising applications not only for exhaust-gas cleaning but also for various chemical reactions.

We propose a molecular dynamics (MD) method based on the multi-component molecular orbital (MC_MO) method, which takes into account the quantum effect of proton directly, for the detailed analyses of proton transfer in hydrogen bonding system. The MC_MO based MD (MC_MO-MD) method is applied to the basic structures, H 5 O 2 + (called “Zundel ion”), and its isotopomers ( D 5 O 2 + and T 5 O 2 + ). We clearly demonstrate the geometrical difference of hydrogen bonded O ⋯ O distance induced by H/D/T isotope effect because the O ⋯ O in H-compound was longer than that in D- or T-compound. We also find the strong relation between stretching vibration of O ⋯ O and the distribution of hydrogen bonded protonic wavefunction because the protonic wavefunction tends to delocalize when the O ⋯ O distance becomes short during the dynamics. Our proposed MC_MO-MD simulation is expected as a powerful tool to analyze the proton dynamics in hydrogen bonding systems.

Because of the fuel flexibility of Solid Oxide Fuel Cells (SOFCs), various types of fuels may be applied directly or via a simple reforming process, including hydrocarbons, alcohols, coal gas, biogas, besides hydrogen. However, various types of minor constituents in practical fuels and/or from the system components can cause chemical degradation of SOFCs, such as anode and cathode poisoning phenomena. In this study, we compare the influence of various external impurities, including sulfur, chlorine, phosphorus, boron, and siloxane for anodes, and H 2 O and SO 2 for cathodes, on SOFC performance to have a general overview on long-term chemical durability of SOFCs. Chemical compatibility of Ni with foreign species has also been thermochemically considered. Using common model cells, the stability of cell voltage, electrode overpotential, and ohmic loss up to 3000 h has been experimentally examined for H 2 -based fuels, for hydrocarbon-based fuels, and for partially pre-reformed CH 4 -based fuels. Increase in degradation rate by impurities was verified for various operational parameters. Impurity poisoning mechanisms are discussed for each specific impurity.

With the development of lithium ion battery (LIB) are recognized as a practical green option for the energy transportation and storage. Over the past decades, solid state batteries (SSB) have received the much attention among the LIB researchers, due to the development of electrolytes with high conductivity comparable to that of the liquid electrolyte. Additionally, the SSB have high energy density, non-flammability and large electrochemical window compared to the conventional liquid electrolytes. The electrolyte for SSB are classified as the oxide and sulphide. Among the solid electrolyte, the oxide electrolytes are considered to be chemically more stable whereas the sulphide electrolytes possessed relatively high ionic conductivity. With the development of the SSB, there is a need for the simulation tools in order to allow the battery engineers to explore the effects of various materials properties, geometries, etc. on the overall performances of the SSB. Simulation studies will provide an opportunity to explore the fundamental phenomena involved and the strategies to optimize the SSB performance. The objectives of this study are twofold. First is the identification of the bulk parameters of the SSB component materials. Second, the estimation of interfacial properties in SSB by utilizing the bulk parameters. In this study, mass transport phenomena and the electrochemical reactions were considered by solving the numerical equations based on the finite element method. The model used includes the diffusion of the lithium in the active material (AM), diffusion of ions in the electrolyte and the charge kinetic transfer at the electrode-electrolyte interface. Firstly, numerical simulations were performed to identify the bulk parameters of the single particle of commonly used positive AM, i.e., LixCoO2 (LCO). The results of this study have been compared with the experimental study conducted by Dokko et al. (2009). The simulated models predict global discharge characteristics that were overall in a good agreement with the experimental result as shown in Figure 1. In the second part of this study, complex three-dimensional micro-structure of the electrode (cathode) was taken into an account. For that purpose, an in-house code was used to model the composite electrode system of SSB, consisting of the idealized micro-structure, i.e., spherical, containing both the AM and solid electrolyte (SE). The simulation model assumes the transport number of the SE is unity, which is usually the case for the SE systems. Additionally, in this study, we have also taken into account the coating of the AM, which is usually done to reduce the contact resistance between the AM and the sulphide SE particles. The model predictions revealed that the concentration of lithium remain unchanged in the SE over a period of time. It is also found from the simulations that a significant concentration gradient developed among the positive AM particles at high discharge current. Reference: Dokko, N. Nakata, K. Kanamura, Journal of Power Sources, 189, (2009) 783–785 Figure 1

数十nmから数μmの不規則な細孔構造を有する多孔体（不規則性多孔体）は、自動車触媒、排ガス処理用フィルタ、燃料電池用電極触媒、リチウム電池用電極触媒などをはじめとして様々な用途に用いられている。これら不規則性多孔体の特性・信頼性向上に向けた研究開発アプローチは、材料物性の制御、相互作用界面に注目した界面制御、大表面積・高活性化のための構造制御、に大別される。このうち構造制御は、理論的に有効な手法が存在せず、実験による経験的試行錯誤による研究開発が大きな役割を果たしてきた。著者らは、不規則性多孔体微細構造の合理的最適化というブレイクスルーに向けて、三次元多孔質シミュレータを開発してきた。本研究では、開発した三次元多孔質シミュレータを固体酸化物燃料電池(SOFC)の燃料極へと具体的に応用し、実験結果に対する合致からその妥当性を確認した。さらに、三次元多孔質シミュレータに基づく微細構造最適化のための手法を提案し、予備的な結果に基づいて提案手法の展開可能性を示すことに成功した。

ATP binding subunit is known as a subunit of ABC transporter, providing energy through the binding of ATP with the subunit and the subsequent hydrolysis reaction of the bound ATP. In this study, density functional theory (DFT) method was used to study the ATP hydrolysis reaction in HisP protein, an ATP binding subunit of Histidine permease HisQMP2, by considering the ATP binding site, especially the � phosphate group, surrounding residues and water molecules. Based on DFT calculations, we proposed that ATP hydrolysis is initiated by the formation of Mg2þ mediated coordinate complex followed by the nucleophilic attack of a single water molecule (Water437) on the � -phosphate; the hydrolysis product ADP acts as a leaving group. The transition state structure was determined by an approximate saddle-point search. [doi:10.2320/matertrans.48.735]

Using accurate DFT calculations we have examined the role that Compound I of cytochrome P450 plays as a catalyst in the conversion of theophylline to 1-methylxanthine. This reaction proceeds in two steps according to the characteristics of the oxygen rebound mechanism. In this study we found that the activation energy for the transition state corresponding to the abstraction of the H atom at the C13 in theophylline is 9.3kcal/mol. This H atom abstraction is the rate-determining step in this reaction which takes place via a single electron transfer (SET) mechanism and leads to an intermediate containing theophylline cationic and iron-hydroxo species. The rebounding step between the reaction intermediate and the product alcohol complex is a barrierless step. The alcohol complex is then separated from the heme moiety and yields 1-methylxanthine by intramolecular rearrangement.