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Aiming at the problems of high investment and low efficiency in the planning and construction of electric vehicle (EV) charging stations in cities, an optimization model for site selection and capacity determination of charging stations considering the uncertainty of users’ dynamic charging demands is proposed. Firstly, based on the travel chain theory and the Origin-Destination (OD) matrix, the travel characteristics of EVs are studied, and the spatial and temporal distribution prediction model of EV charging load is established through the dynamic Dijkstra algorithm combined with the Monte Carlo method. Secondly, a site selection model for the charging station is established which takes the minimum annualized cost of the charging station operator and the annualized economic loss of the EV users as the goal. At the same time, the weighted Voronoi diagram and Adaptive Simulated Annealing Particle Swarm Optimization algorithm (ASPSO) are adopted to determine the optimal number/site selection and service scope of charging stations. Finally, an uncertain scenario set is introduced into the capacity determination model to describe the uncertainty of the users’ dynamic charging demands, and the robust optimization theory is utilized to solve the capacity of the charging station. A case study is carried out for the EV charging station planning problem in some urban areas of a northern city, and the validity of the model is verified.

Transition metal compounds with partially filled 3d electron shells exhibit a variety of physical and chemical properties. They are widely used in sensors, magnetic memory, photoelectronic devices, photocatalysis, and electrochemistry. Therefore, determining and understanding their electronic structure is extremely important. The quantitative analysis of soft X-ray absorption spectroscopy depends on theoretical calculation method for the full multiplet based on crystal field theory and hybridization theory. By incorporating these elements, full multiplet theory can provide an accurate model of the fine electronic structure of transition metals and their ligands. A brief introduction of the basic principles, key parameters, and software relevant to soft X-ray absorption spectroscopy is firstly provided in this review. Subsequently, the applications of theoretical calculation in analyzing the electronic structures of 3d transition metals are discussed with an emphasis on its application in the field of electrochemistry. Finally, some prospects for future development in this field are proposed.

BACKGROUND Microwave digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) is a commonly used method for the determination of metal elements in soil samples. Different solvents can be used in the pretreatment, and the digestion method has a great influence on the accuracy of the analysis results. In addition, the accuracy of the results will be affected by the interference in the determination of some elements by ICP-MS. OBJECTIVES To accurately determine metal elements in soil samples by high resolution-inductively coupled plasma-mass spectrometry (HR-ICP-MS). METHODS Soil samples were digested by microwave using three different solvents, and 8 metal elements (Cr, Co, Ni, Cu, Zn, Pb, Cd and U) were determined by HR-ICP-MS. The digestion effects of the three acid digestion methods using different amounts of nitric acid, hydrochloric acid and hydrofluoric acid on certified soil reference materials were studied, and the optimal pretreatment procedure was determined. RESULTS The proposed procedures have been verified by national soil reference materials. It was found that the measured values of digestion method Ⅰ(6mL HNO3+3mL HCl+3mL HF) and digestion method Ⅱ(2mL HNO3+6mL HCl+1mL HF) were consistent with the certified values, using HR-ICP-MS without interference correction. The detection limits of both procedures were 0.001-0.715μg/g. The relative standard deviations (RSD, n=6) were all less than 7.0%. In terms of digestion, accuracy and precision, acid system Ⅰ was slightly better than acid system Ⅱ, but acid system Ⅱ had the least amount of acid. CONCLUSIONS The two preferred procedures have high applicability and reliability, and can be used for the direct determination of 8 metal elements in soil samples.

High-performance anodic electrocatalysts are urgently required for proton exchange membrane (PEM)-based water electrolysis. Here, a simple one-step approach is introduced to produce atomically dispersed Ru on iridium oxide (Ru-IrOx) sub-nanoclusters, aiming to simultaneously enhance the activity and durability of the electrocatalyst toward acidic oxygen evolution reaction (OER). The resulting catalyst shows a low overpotential (η) of 237 mV at 10 mA cm−2 in acidic media and demonstrates exceptional durability by sustaining a constant current of 100 mA cm−2 for 150 hours. Real-time electrochemical impedance spectroscopy (EIS) measurements and in situ Raman spectra unveil the formation of a further oxidized layer on the surface that prevents the degradation of the catalyst. In addition, operando differential electrochemical mass spectrometry (DEMS) coupled with isotope labelling measurements ascertains that the catalysis process follows the adsorbate evolution mechanism (AEM), corresponding to outstanding stability. [ABSTRACT FROM AUTHOR]

For protonic ceramic fuel cells, it is key to develop material with high intrinsic activity for oxygen activation and bulk proton conductivity enabling water formation at entire electrode surface. However, a higher water content which benefitting for the increasing proton conductivity will not only dilute the oxygen in the gas, but also suppress the O2 adsorption on the electrode surface. Herein, a new electrode design concept is proposed, that may overcome this dilemma. By introducing a second phase with high‐hydrating capability into a conventional cobalt‐free perovskite to form a unique nanocomposite electrode, high proton conductivity/concentration can be reached at low water content in atmosphere. In addition, the hydronation creates additional fast proton transport channel along the two‐phase interface. As a result, high protonic conductivity is reached, leading to a new breakthrough in performance for proton ceramic fuel cells and electrolysis cells devices among available air electrodes. [ABSTRACT FROM AUTHOR]

BackgroundThe performance of solid oxide fuel cells (SOFCs) can be promoted by optimizing cathode materials.PurposeThis study aims to boost the electrochemical performances of cathodes for SOFCs by doping transition metal at the B-site of double perovskite.MethodsFirstly, a series of B-site doped PrBa0.8Ca0.2Co2O5+δ (PBCC) oxides as cathodes for SOFCs were prepared by sol-gel. The effects of B-site doped content and doped elements on the crystalline structure of the cathodes were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Then, the trends of conductivity and thermal expansion coefficient with B-site doped PBCC oxides were investigated. Finally, the electrochemical performances of cathodes with different B-site doped PBCC oxides were tested to find optimal doping element type and content.ResultsTest results show that polarization is reduced and the electrochemical catalytic activity is improved when 5 mol% of Fe is doped on the B-site of the PBCC cathode. Compared to the PBCC cathode, the max power density of the full cell with a 5-mol% Fe-doped cathode increases from 988 mW∙cm-2 to 1 259 mW∙cm-2 at 700 ℃.ConclusionsThe electrochemical performances of SOFCs can be boosted by modifying the B-site of double perovskite using transition metal.

The electrochemical reduction of CO2 to CO is a powerful approach to achieving carbon neutrality. Herein, we report a five-nuclear copper cluster-based metal–azolate framework CuTz-1 as an electrocatalyst for the electrochemical CO2 reduction reaction. It achieved a faradaic efficiency (FE) of 62.7% for yielding CO with a partial current density of −35.1 mA cm−2 in flow cell device, which can be preserved for more than ten hours with negligible changes of the current density and FE(CO). Studies of electrocatalytic mechanism studies revealed that the distance of Cu–N was increased, and the coordination number of the Cu ion was reduced, while the oxidation state of Cu was decreased after the electrocatalysis. These findings offer valuable insights into structural changes that influence the performance of the catalyst during the process of the electrochemical reduction of CO2 process. [ABSTRACT FROM AUTHOR]