Electrical Transport Research Articles

Charge Transfer Mechanism in Guanine-Based Self-Assembled Monolayers on a Gold Surface.

In this work, we have theoretically determined the one-electron oxidation potentials and charge transfer mechanisms in complex systems based on a self-assembled monolayer of guanine molecules adsorbed on a gold surface through different organic linkers. Classical molecular dynamics simulations were carried out to sample the conformational space of both the neutral and the cationic species. Thus, the redox potentials were determined for the ensembles of geometries through multiscale quantum-mechanics/molecular-mechanics/continuum solvation model calculations in the framework of the Marcus theory and in combination with an additive scheme previously developed. In this context, conformational sampling, description of the environment, and effects caused by the linker have been considered. Applying this methodology, we unravel the phenomena of electric current transport by evaluating the different stages in which charge transfer could occur. The results revealed how the positive charge migrates from the organic layer to the gold surface. Specifically, the transport mechanism seems to take place mainly along a single ligand and driven with the help of the electrostatic interactions of the surrounding molecules. Aside, several self-assembled monolayers with different linkers have been analyzed to understand how the nature of that moiety can tune the redox properties and the efficiency of the transport. We have found that the conjugation between the guanine and the linker, at the same time conjugated to the gold surface, gives rise to a more efficient transport. In conclusion, the established computational protocol sheds light on the mechanism behind charge transport in electrochemical DNA-based biosensor nanodevices.

Developing Catalysts for Membrane Electrode Assemblies in High Performance Polymer Electrolyte Membrane Water Electrolyzers.

Extensive research is underway to achieve carbon neutrality through the production of green hydrogen via water electrolysis, powered by renewable energy. Polymer membrane water electrolyzers, such as proton exchange membrane water electrolyzer (PEMWE) and anion exchange membrane water electrolyzer (AEMWE), are at the forefront of this research. Developing highly active and durable electrode catalysts is very important for commercializing these electrolyzers. However, most research is conducted in half-cell setups, which may not fully represent the catalysts' effectiveness in membrane-electrode-assembly (MEA) devices. This review explores the catalysts developed for high-performance PEMWE and AEMWE MEA systems. Only the catalysts reporting the MEA performance were discussed in this review. In PEMWE, strategies aim to minimize Ir use for oxygen evolution reaction (OER) by maximizing activity, employing metal oxide-based supports, integrating secondary elements into IrOx lattices, or exploring non-Ir materials. For AEMWE, the emphasis is on enhancing the performance of NiFe-based and Co-based catalysts by improving electrical conductivity and mass transport. Pt-based and Ni-based catalysts for hydrogen evolution reaction (HER) in AEMWE are also examined. Additionally, this review discusses the unique considerations for catalysts operating in pure water within AEMWE systems.

Electrical transport in nanostructured Ni3Al at low temperatures

The electrical resistivity in nanostructured Ni3Al has been discriminated to be dominated fully by the electron-magnon scattering with spin fluctuations and evolve in the form of T 5/3 and T 3/2 below and above its Curie temperature. In addition to doping into γ′-Ni3Al nanophases, excessive Ni atoms are demonstrated to aggregate at the cores of Ni3Al so that some γ-Ni nanophases are embedded in the γ′-Ni3Al ones for forming the core/shell nanostructure. The itinerant electrons from γ′-Ni3Al nanophases is further suggested to wander around the phonons in both γ-Ni and γ′-Ni3Al nanophases for screening the electron-phonon interactions. Consequently, the conduction electrons are scattered largely by spin fluctuations in γ′-Ni3Al shells to suppress the contribution of phonons to the electron transport in nanostructured Ni3Al.

Room‐Temperature Out‐of‐Plane Ferroelectricity and Resistance Switching Based on 2D Bi2O2Se

AbstractAlthough 2D Bi2O2Se plays an important role in the electronics and optoelectronics based on its in‐plane property, its out‐of‐plane electrical transport behavior remains unclear, especially in fabricating vertical devices with high integration density for novel functionality. Here, a solution‐processed method is developed to prepare 2D Bi2O2Se with mass production (e.g., hundreds of milliliter scale). The out‐of‐plane ferroelectric property of 2D Bi2O2Se is observed by piezoresponse force microscopy and the ferroelectric dipole map atom‐by‐atom at the Bi2O2Se surface, which shows an atomically resolved dipolar displacement of Se ions. The out‐of‐plane resistant switching property of 2D Bi2O2Se is revealed by conductive atomic force microscopy. Moreover, the electric field on the local polarization of Bi2O2Se is addressed by using ab initio simulations, which shows a broken inversion symmetry along the z‐axis of Bi2O2Se. The working mechanism of resistant switching behavior in Bi2O2Se is attributed to the diffusion and shuttle of Se ions. Besides, a controllable wet‐assembled method is developed to prepare Bi2O2Se thin film with centimeter scale and explores its application on photodetectors under 808 nm laser light. This work reveals the unique out‐of‐plane transport behavior of 2D Bi2O2Se, providing the basis for fabricating multifunctional devices with high integration based on this 2D material.

Pressure tuning of superconductivity in TiN thin films

Abstract Titanium nitride (TiN) thin films are used for the fabrication of superconducting devices due to their chemical stability against oxidization and high quality at interfaces. The high-pressure technique serves as a useful tool to understand the mechanical and electrical properties of materials, which is crucial for practical applications. However, high-pressure transport measurements of thin films are extremely difficult due to the limited sample space of high-pressure cells and the fragility of thin films. Here, we successfully carried out high-pressure electrical transport and Raman measurements on TiN films up to ~50 GPa. The superconducting transition temperature gradually decreases with increasing pressure, which can be attributed to the decrease of electron -phonon coupling and is consistent with our first-principles calculations. In addition, the coexistence of a symmetry-enforced Dirac nodal chain and a nodal box is revealed by our calculations in TiN. Our work provides a promising way to study the physical properties of thin films at high pressure, which would broaden the high-pressure research field.

Electrical transport and dielectric relaxation mechanism in Zn0.5Cd0.5Fe2O4 spinel ferrite: A temperature- and frequency-dependent complex impedance study

In the present study, the frequency-dependent dielectric relaxation and electrical conduction mechanisms in sol-gel-derived Zn0.5Cd0.5Fe2O4 (ZCFO) spinel ferrite were studied in the temperature range of 343–438 K. The formation of the ZCFO spinel ferrite phase with space group Fd3m was confirmed by X-ray diffraction analysis. The dielectric relaxation and electrical conduction mechanisms were studied using complex impedance spectroscopy (CIS). In the Nyquist plots, depressed semicircles were fitted with an equivalent circuit model with configuration (RGBQGB) (RGQG), signifying the contributions from grain boundaries and grains to the charge transport mechanism in the sample. The frequency-dependent AC conductivity was found to follow Jonscher's power law, and the frequency exponent term depicted the overlapping large polaron hopping (OLPH) model as the dominant transport mechanism. The activation energies for conductivity, electric modulus and impedance were calculated to identify the nature of the charge carriers governing the relaxation and conduction mechanisms in the prepared sample. Complex modulus studies confirmed the non-Debye type of dielectric relaxation, whereas tangent loss and dielectric constant analyses confirmed the thermally activated hopping mechanism of charge carriers in Zn0.5Cd0.5Fe2O4 spinel ferrite.

Comparative Analysis of BEST Buses and Electric Buses in India

An overwhelming trend that marks the beginning of the transportation sector’s energy transition is the electrification of public transportation. The public sector’s considerable influence and predominance of public ownership define the transportation industry. Consequently, tendering processes Are frequently used to determine which bus delivery options are the most efficient. Based on a comprehensive analysis of the Polish bus market and in-depth interviews with individual vendors, this paper compares, assesses, and delineates the distinctions between the criteria applied in tenders for battery electric buses and diesel buses. The article additionally endeavors to ascertain whether the proportion of the vehicle price in the life cycle cost or total cost of ownership aligns with the weight assigned to the “vehicle price” criterion. The outcomes show There isn't a noticeable distinction between diesel and battery electric buses' tender requirements. Institutions that had previously created diesel bus acquisition patterns applied those patterns, for the most part, to battery electric bus tenders. As a result, the weights assigned to the criteria in tenders do not account for the benefits and drawbacks of either technology. Procedures for tendering are modified to meet regional needs and operational specifications. On current routes and schedules, electric buses frequently take the place of conventionally powered vehicles. Operational requirements are therefore known. This makes it possible to calculate the required number of vehicles as well as the fundamental technical and operational parameters (such as choosing the best charging technique and battery capacity). The charging strategy will therefore have an impact on the overall cost of ownership Opportunity charging is preferred for longer mileages, and overnight charging is preferred for shorter assignments.The electrification of public transportation is a massive trend that represents the first stage of the energy transition of the transportation sector. The transportation industry is defined by the significant influence of the public sector and the prevalence of public ownership. As such, tendering proceduresare widely employed to identify the most effective bus delivery options. This paper compares, evaluates, and discusses the differences between the specifications used in tenders for battery electric buses and diesel buses. It is based on a thorough examination of the Polish bus market and indepth interviews with specific vendors. The piece also aims to determine whether the percentage of the car price in the life cycle cost or overall cost of ownership is consistent with the importance given to the "vehicle price" factor. The results reveal no appreciable.

Electrochemical Doping of Two-Dimensional Superatomic Materials.

We report an electrochemical method for doping two-dimensional (2D) superatomic semiconductor Re6Se8Cl2 that significantly improves the material's electrical transport while retaining the in-plane and stacking structures. The electrochemical reduction induces the complete dissociation of chloride anions from the surface of each superatomic nanosheet. After the material is dehalogenated, we observe the electrical conductivity (σ) increases by two orders of magnitude while the 3D electron carrier density (n3D) increases by three orders of magnitude. In addition, the thermal activation energy (Ea) and electron mobility (μe) decrease. We conclude that we have achieved effective electron-doping in 2D superatomic Re6Se8Cl2, which significantly improves the electrical transport properties. Our work sets the foundation for electrochemically doping and tuning the transport properties of other 2D superatomic materials.

Energy Consumption and Saved Emissions of a Hydrogen Power System for Ultralight Aviation: A Case Study

The growing concern about climate change and the contemporary increase in mobility requirements call for faster, cheaper, safer, and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this direction. The goal of this investigation is a comparative analysis of the environmental impact of conventional and hydrogen-based propulsive systems. As a case study, a hybrid electric configuration consisting of a fuel cell with a nominal power of about 30 kW, a 6 kWh LFP battery, and a pressurized hydrogen vessel is proposed to replace a piston prop configuration for an ultralight aerial vehicle. Both power systems are modeled with a backward approach that allows the efficiency of the main components to be evaluated based on the load and altitude at every moment of the flight with a time step of 1 s. A typical 90 min flight mission is considered for the comparative analysis, which is performed in terms of direct and indirect emissions of carbon dioxide, water, and pollutant substances. For the hydrogen-based configuration, two possible strategies are adopted for the use of the battery: charge sustaining and charge depleting. Moreover, the effect of the altitude on the parasitic power of the fuel cell compressor and, consequently, on the net efficiency of the fuel cell system is taken into account. The results showed that even if the use of hydrogen confines the direct environmental impact to the emission of water (in a similar quantity to the fossil fuel case), the indirect emissions associated with the production, transportation, and delivery of hydrogen and electricity compromise the desired achievement of pollutant-free propulsion in terms of equivalent emissions of CO2 and VOCs if hydrogen is obtained from natural gas reforming. However, in the case of green hydrogen from electrolysis with wind energy, the total (direct and indirect) emissions of CO2 can be reduced up to 1/5 of the fossil fuel case. The proposed configuration has the additional advantage of eliminating the problem of lead, which is used as an additive in the AVGAS 100LL.

Enhanced Thermoelectric Performance in Flexible Sulfur-Alloyed Ag2Se Thin Films.

Flexible thermoelectric generators can directly convert thermal energy harvested from the human body into electricity. The Ag2Se flexible film, a promising material for wearable thermoelectric generators, normally demonstrates an inferior electrical transport property due to its weakened in-plane mobility. In this study, the in-plane electrical transport properties of flexible Ag2Se films were optimized by alloying with additional sulfur. This optimization is achieved by leveraging the differences in elemental electronegativity and the preferred orientation of the Ag2Se films. The sulfur-alloyed Ag2Se thin film, with a nominal ratio of 3 atom %, can reach a maximum mobility of 1150 cm-2 V-1 s-1 at 300 K. So, the optimized room-temperature power factor increases to 1935 μW m-1 K-2. Furthermore, the Ag2Se film alloyed with 3 atom % sulfur exhibits excellent flexibility even after 1000 bending cycles with a radius of 5 mm, characterized by a relative resistance increment of less than 3%. In addition, the corresponding π-type flexible thermoelectric generator possesses a maximum power density of 51 W m-2 at a temperature difference of 50 K.

A simple in-situ PZT oxide's decomposition: Realizing synergistic tailoring of electrical and thermal transport properties of BiCuSeO thermoelectric ceramics through band and phonon engineering

BiCuSeO, an oxide thermoelectric material with a superlattice structure, presents the advantages of affordability, low toxicity, and environmental friendliness. However, its intrinsic low electrical conductivity has impeded its possible applications. To address this challenge, we put tiny PbZr0.52Ti0.48O3 (PZT) with varying weight percentages (x = 0, 5, 7, 9, 11) into BiCuSeO (BCSO) to fabricate thermoelectric nanocomposites. Through the spark plasma sintering process, PZT particles underwent in-situ decomposition, generating nano-sized second phases such as PbO2, TiO2, and PbZrO3, which are homogenously distributed within BCSO matrix (validated by XRD and TEM). The introduced PbO2, TiO2, and PbZrO3 second phases served a dual purpose: inhibiting the grain growth of BCSO and introducing additional nano-grain boundaries. This resulted in more effective phonon scattering sites, thereby reducing lattice thermal conductivity. Simultaneously, the Pb element derived from PZT decomposition was doped into the Bi site of the BCSO matrix, causing a reduction in the band gap of BCSO from 0.49 eV to 0.388 eV and a significant increase in carrier concentration. Consequently, this doping enhanced the electrical conductivity of BCSO-based composites, with the composite with 11 wt% PZT additive amount exhibiting a remarkable 318-fold increase, reaching 550 S/cm compared to pristine BCSO. Notably, the composite with 7 wt% PZT additive amount achieved an exceptionally low lattice thermal conductivity of 0.333 W m−1 K−1 at 823 K. Through the synergistic optimization of electrical and thermal transport properties, the BCSO-based composite with 7 wt% PZT additive amount obtained a ZT value of ∼0.9 at 873 K, representing a 2.45-fold increase compared to pristine BiCuSeO. This straightforward method presents a cost-effective and scalable approach to enhance the thermoelectric performance of various materials, opening new avenues for potential commercial applications.

Аналіз факторів впливу на споживання електроенергії при запровадженні «Концепції «зеленого» енергетичного переходу України до 2050 року»

On the way to EU membership, Ukraine joined the "European Green Deal", which aims to achieve zero greenhouse gas emissions and zero environmental pollution by transitioning from the use of fossil fuels to renewable sources of energy and raw materials in the member states of the European Union by 2050. The concept of the "green" energy transition of Ukraine by 2050 was formulated, which involves a change in approaches to the development of energy with an emphasis on the problem of combating climate change and sustainable economic development. When achieving the goals of the "green" transition, it is important to understand which factors have the greatest impact on electricity consumption. It is promising to include such factors in electricity demand forecasting models. These models will become increasingly important to ensure network reliability and efficiency. Identifying the factors that affect energy consumption can drive innovation in energy-efficient technologies and practices. The article concludes that electricity consumption in Ukraine is affected by the same main factors as in other countries of the world. The desired reduction in electricity consumption can be achieved both by purely economic measures (increasing tariffs) and by more acceptable, technological measures. However, in the conditions of war, there are additional difficulties, such as the difficulty of forecasting the structure, state, and development of the energy system on the energy market. A significant part of the population now has more urgent problems than energy conservation, so the role of the state in this issue is increasing. Ukraine's energy system has already suffered significant destruction, and this process is ongoing and may continue for an indefinite period of time. Despite the difficulties, the lost power system equipment is gradually being replaced with new, more technologically advanced equipment. Some of the enterprises that had significant consumption were either lost or failed. The most adapted to new problems turned out to be the trade sector and the service sector and part of the population. Here, there is a rapid transition to the use of own generators, solar panels and electric transport, which reduces the consumption of electricity from the state power system. Industry, taking into account the funds required for this, will replace technologies with more energy-efficient ones after the end of the active phase of the war. Keywords: "green" transition, energy efficiency, electricity consumption, electricity demand forecasting, energy system.

Enhanced thermoelectric performance of MoSe2 under high pressure and high temperature by suppressing bipolar effect

The electrical transport property of layered MoSe2 has a strong response to high pressure by enhancing the inter-layer interaction. However, the narrowed bandgap under high pressure will cause the bipolar effect (i.e., the thermally excited minority carriers contribute to a Seebeck coefficient with the opposite sign to the majority carriers) at high temperatures to degrade the thermoelectric (TE) performance. Hence, suppressing the bipolar effect is important to optimize the TE performance of MoSe2 under high pressure and high temperature (HPHT). In this study, the degradation of TE performance caused by the bipolar effect under HPHT in MoSe2 is investigated. It is found that in MoSe2, the electrical conductivity was improved significantly by pressure; however, the bipolar effect led to a significantly degraded Seebeck coefficient at high temperatures. By injecting massive carriers beforehand, the bipolar effect was suppressed to make a dominant type of p-type charge carries, achieving an increased Seebeck coefficient with increasing temperature, resulting in an improved power factor from 29.3 μW m−1 K−2 in MoSe2 to 285.7 μW m−1 K−2 in Mo0.98Nb0.02Se2 at 5.5 GPa, 1110 K. Combined with the reduced thermal conductivity by point defect scattering on phonons, a maximum ZT value of 0.11 at 5.5 GPa, 1110 K. This work highlights the significance of suppressing the bipolar effect under HPHT for optimizing TE performance in such layered semiconductors.

High pressure coupled with Cu deficiency boosts thermoelectric performance in BiCuSeO oxides

Low carrier concentration and mobility have been the primary obstructions to improving the electrical transport properties of BiCuSeO thermoelectric oxides, particularly for excessively low carrier mobility, heavily impeding the development of its thermoelectric performance. Herein, high-pressure technology is adopted to tune the electronic structure motivating carrier mobility, incorporated with the contribution of Cu deficiency to carrier concentration, achieving high carrier mobility of 25 cm2V−1s−1 and outstanding electrical conductivity of 2834.57 Sm−1. Moreover, high densities of grain boundaries and dislocations are introduced by high pressure, accompanied by the effect of Cu vacancies, suppressing phonon transport and depressing lattice thermal conductivity, finally realizing an acceptable zT of 0.56 at 823 K in BiCu0.97SeO. This work demonstrates that high pressure can be compatible with other methods, realizing synergetic optimizations in coupled parameters and thus improving thermoelectric performance in BiCuSeO oxides.

Improving the Efficiency of Electric Vehicles: Advancements in Hybrid Energy Storage Systems

Electric vehicles (EVs) encounter substantial obstacles in effectively managing energy, particularly when faced with varied driving circumstances and surrounding factors. This study aims to evaluate the performance of three different control systems in a fully operational hybrid energy storage system (HESS) installed in the Nissan Leaf. The objective is to improve the performance of EVs by focusing on optimising energy management in response to different global environmental and driving circumstances. This study utilises an analytical strategy by developing a distinct energy management system model using MATLAB/Simulink. This model is specifically designed for optimising the integration and control of batteries and supercapacitors (SCs) in a fully active HESS. This model mimics the performance of the controllers under three different driving cycles—Artemis rural, Artemis motorway, and US06. The findings demonstrate notable progress in managing the battery state of charge (SOC) and the system’s responsiveness, especially when employing the radial basis function (RBF) controller. This study emphasises the capacity of HESSs to enhance the effectiveness and durability of EVs, therefore promoting wider acceptance and progress in electric transportation technology.

High wide-temperature-range thermoelectric performance in GeTe through hetero-nanostructuring

GeTe is emerging as promising medium-temperature thermoelectric material due to its highly competitive performance and good mechanical properties. Strong Rashba spin splitting was harnessed to markedly improve the Seebeck coefficient and power factor of Bi and Sn codoped GeTe at low-medium temperature. Moreover, it is found that Bi-Sn-Cu doping reduces the phase-transition temperature to extend better electrical transport behavior of cubic phase to low temperature. As a result, the electrical transport properties in low-medium temperature were overall enhanced. In the meanwhile, endotaxial hetero-nanostructures efficiently scatter phonons and play a dominant role on affecting phonon propagation. The lattice thermal conductivity was reduced to 0.2 W m−1K−1 at 673 K. Drive by strengthening Rashba effect and endotaxial hetero-nanostructures, a record-high average ZT (300–823 K) of 1.6 and a high ZT of 2.1 were obtained in lead-free GeTe-based compounds. The vast increase of ZT promotes GeTe as a promising candidate for a wide range of applications in waste heat recovery and power generation.

Sustainable transport in the face of the energy crisis related to the war in Ukraine

The energy crisis caused by Russia’s aggression in Ukraine has had a huge impact on the functioning of many countries in various spheres. The Russian Federation was the main supplier of many raw materials, which had to be abandoned as a result of the sanctions that were imposed. Consequently, the prices of various commodities – primarily natural gas, crude oil and coal – have risen. This posed a particular challenge for Poland, which is highly dependent on coal. At the same time, Poland, being a Member State of the European Union, has committed to achieving the goals of climate neutrality and the related concept of sustainable transport. In this light, the author analysed the issue of striving for climate neutrality and sustainable transport in the conditions of the crisis caused by the war in Ukraine. It seems appropriate, for instance, to determine whether the energy crisis has led to a collapse of the European Union’s climate policy and a change in its objectives. The process of the electrification of transportation, which, as a result of the current situation, may have become more challenging to implement, should also be considered.

A latent-based segmentation framework for the investigation of charging behaviour of electric vehicle users

Electrification of transport is deemed by many countries worldwide as one of the key strategies to mitigate CO2 emissions, yet the availability of reliable public charging infrastructure systems represents a potential serious bottleneck to such endeavours. Existing studies exploring battery electric vehicle (BEV) charging behaviour are typically based on either non-representative samples or stated choices experiments. This paper analyses observational data from a representative sample of German BEV owners who provided information on mileage and charging activities over a timeframe of eight weeks. BEV charging patterns, related vehicles kilometres travelled (VKT) and battery charging behaviour are assessed via a multifaceted empirical framework that pairs a hazard survival-based model with a log linear regression approach. A latent class method is also employed to segment BEV owners into different charging segments. The model suggests two types of charging behaviour exist, consisting of regular and irregular chargers. Charging frequencies and patterns are found to be radically different between the two groups under study, with regular chargers estimated to charge their vehicles 1.5 times more than irregular chargers. Lastly, the framework proposed is used to explore how charging behaviour will mutate due to both technology advancements (BEV driving range improvements) and user-centric factors (VKT variations). Neither technological or user factors are predicted to substantially affect the inter-charging duration of irregular chargers, whereas both increasing BEV driving ranges and reducing VKT results in a longer elapsed time between two consecutive charges for regular chargers.

MBE growth of Ge1-xSnx devices with intrinsic disorder

MBE growth of Ge1-xSnx devices with intrinsic disorder

Polarization-dependent electrical transport and thermoelectric properties in (010) surface of λ-Ti3O5

In recent research, the (010) surface of λ-Ti3O5 has demonstrated outstanding capabilities in light absorption and molecular adsorption, promising various applications. In this study, we employed density functional theory (DFT) to analyze the optical and thermoelectric properties of the (010) surface of λ-Ti3O5. Our findings reveal the excellent in-plane anisotropy of the optical anisotropy of bulk λ-Ti3O5 and thermoelectric properties in its (010) surface. The figure of merit (ZT) along the groove structure direction reaches 2.4, while the ZT perpendicular to it is only 0.85. In addition, the electrical transport characteristics along the (010) surface exhibit significant nonlinear characteristics. Our research results indicate that it has the potential to become a favorable material for optical and electronic devices.