Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

Electrochemical production of hydrogen from water requires the development ofelectrocatalysts that are active,stable,and low-cost for water splitting.To address these challenges,researchers are increasingly exploring binder-free electrocatalytic integratedelectrodes (IEs) as an alternative to conventional powder-based electrode preparation methods,for the former is highly desirable to improve the catalytic activity and long-term stability for large-scale applications of electrocatalysts.Herein,we demonstrate a laser-inducedhydrothermal reaction (LIHR) technique to grow NiMoO4nanosheets on nickel foam,which is then calcined under H2/Ar mixed gases to prepare the IE IE-NiMo-LR.This electrode exhibits superior hydrogen evolution reaction performance,requiring overpotentials of 59,116 and143 mV to achieve current densities of 100,500 and 1000 mA·cm-2.During the 350 h chronopotentiometry test at current densities of 100 and 500 m A·cm-2,the overpotentialremains essentially unchanged.In addition,NiFe-layered double hydroxide grown on Ni foam is also fabricated with the same LIHR method and coupled with IE-NiMo-IR to achieve water splitting.This combination exhibits excellent durability under industrial current density.The energy consumption and production efficiency of the LIHR method are systematicallycompared with the conventional hydrothermal method.The LIHR method significantly improves the production rate by over 19 times,while consuming only 27.78%of the total energy required by conventional hydrothermal methods to achieve the same production.

Anomalous Josephson effect between d-wave superconductors through a two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting

Based on the Bogoliubov-de Gennes equation and the extended McMillan’s Green’s function formalism,we study theoretically the Josephson effect between two d-wave superconductors bridged by a ballistic two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting.We show that due to the interplay of Rashba spin-orbit coupling and Zeeman splitting and d-wave pairing,the current-phase relation in such a heterostructure may exhibit a series of novel features and can change significantly as some relevant parameters are tuned.In particular,anomalous Josephson current may occur at zero phase bias under various different situations if both time reversal symmetry and inversion symmetry of the system are simultaneously broken,which can be realized by tuning some relevant parameters of the system,including the relative orientations and the strengths of the Zeeman field and the spin-orbit field in the bridge region,the relative orientations of the a axes in two superconductor leads,or the relative orientations between the Zeeman field in the bridge region and the a axes in the superconductor leads.We show that both the magnitude and the direction of the anomalous Josephson current may depend sensitively on these relevant parameters.

Water Splitting:From Electrode to Green Energy System

Hydrogen(H2)production is a latent feasibility of renewable clean energy.The industrial H2 production is obtained from reforming of natural gas,which consumes a large amount of nonrenewable energy and simultaneously produces greenhouse gas carbon dioxide.Electrochemical water splitting is a promising approach for the H2 production,which is sustainable and pollution-free.Therefore,developing efficient and economic technologies for electrochemical water splitting has been an important goal for researchers around the world.The utilization of green energy systems to reduce overall energy consumption is more important for H2 production.Harvesting and converting energy from the environment by different green energy systems for water splitting can efficiently decrease the external power consumption.A variety of green energy systems for efficient producing H2,such as two-electrode electrolysis of water,water splitting driven by photoelectrode devices,solar cells,thermoelectric devices,triboelectric nanogenerator,pyroelectric device or electrochemical water-gas shift device,have been developed recently.In this review,some notable progress made in the different green energy cells for water splitting is discussed in detail.We hoped this review can guide people to pay more attention to the development of green energy system to generate pollution-free H2 energy,which will realize the whole process of H2 production with low cost,pollution-free and energy sustainability conversion.

Perspective of hydrogen energy and recent progress in electrocatalytic water splitting

As a secondary energy with great commercialization potential,hydrogen energy has been widely studied due to the high calorific value,clean combustion products and various reduction methods.At present,the blueprint of hydrogen energy economy in the world is gradually taking shape.Compared with the traditional high-energy consuming methane steam reforming hydrogen production method,the electrocatalytic water splitting hydrogen production stands out among other process of hydrogen production owning to the mild reaction conditions,high-purity hydrogen generation and sustainable production process.Basing on current technical economy situation,the highly electric power cost limits the further promotion of electrocatalytic water splitting hydrogen production process.Consequently,the rational design and development of low overpotential and high stability electrocatalytic water splitting catalysts are critical toward the realization of low-cost hydrogen production technology.In this review,we summarize the existing hydrogen production methods,elaborate the reaction mechanism of the electrocatalytic water splitting reaction under acidic and alkaline conditions and the recent progress of the respective catalysts for the two half-reactions.The structure-activity relationship of the catalyst was deep-going discussed,together with the prospects of electrocatalytic water splitting and the current challenges,aiming at provide insights for electrocatalytic water splitting catalyst development and its industrial applications.

Recent Progress and Approaches on Carbon-Free Energy from Water Splitting

Sunlight is the most abundant renewable energy resource,providing the earth with enough power that is capable of taking care of all of humanity’s desires-a hundred times over.However,as it is at times diffuse and intermittent,it raises issues concerning how best to reap this energy and store it for times when the Sun is not shining.With increasing population in the world and modern economic development,there will be an additional increase in energy demand.Devices that use daylight to separate water into individual chemical elements may well be the answer to this issue,as water splitting produces an ideal fuel.If such devices that generate fuel were to become widely adopted,they must be low in cost,both for supplying and operation.Therefore,it is essential to research for cheap technologies for water ripping.This review summarizes the progress made toward such development,the open challenges existing,and the approaches undertaken to generate carbon-free energy through water splitting.

Probing nucleon effective mass splitting with light particle emission

The main objective of this study was to investigate the impact of effective mass splitting on heavy-ion-collision observables.We first analyzed correlations between different nuclear matter parameters obtained from 119 effective Skyrme interaction sets.The values of the correlation coefficients illustrate that the magnitude of effective mass splitting is crucial for tight constraints on the symmetry energy via heavy-ion collisions.The^(86)Kr+^(208)Pb system at beam energies ranging from 25 to 200A MeV was simulated within the framework of the improved quantum molecular dynamics model(ImQMD-Sky).Our calculations show that the slopes of the spectra of ln[Y(n)/Y(p)]and ln[Y(t)/Y(^(3)He)],which are the logarithms of the neutron to proton and triton to helium-3 yield ratios,are directly related to effective mass splitting and can be used to probe the effective mass splitting.

Integration of earth-abundant cocatalysts for high-performance photoelectrochemical energy conversion

Photoelectrochemical(PEC)energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and storage.By utilizing semiconductor photoelectrodes,PEC devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide(CO_(2))reduction to generate clean fuels and value-added chemicals.However,PEC energy conversion faces several challenges such as high overpotential,sluggish reaction kinetics,charge carrier recombination,and stability issues,which limit its practical implementation.Recently,significant research has been conducted to improve the overall conversion efficiency of PEC devices.One particularly promising approach is the use of cocatalysts,which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation,improve reaction kinetics,and reduce the overpotential,thereby enhancing the overall performance of PEC energy conversion.This review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO_(2) reduction.The main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide(TMD)-based materials,metal phosphides/carbides,and metal oxides/hydroxides.Meanwhile,PEC-CO_(2)RR was divided into C_(1) and C_(2+)based on the final product since various products could be produced,focusing on diverse earth-abundant materials-based cocatalysts.In addition,we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with cocatalysts.Finally,the current problems associated with PEC systems are discussed along with a suggested direction to overcome these obstacles.

Constraints on symmetry energy and n/p effective mass splitting with improved quantum molecular dynamics model

A new version of improved quantum molecular dynamics model that includes standard Skyrme interactions has been developed.Based on the new code,four commonly used parameter sets,SLy4,SkI2,SkM*and Gs are adopted in the improved quantum molecular dynamics model and the isospin sensitive observables,namely isospin transport ratios,single and double ratios of the yields of neutrons and protons are investigated.The isospin transport ratios are strongly sensitive to the slope of symmetry energy,and are not very sensitive to the nucleon effective mass splitting.On the other hand,the high energy neutrons and protons yields ratios from reactions at different incident energies provide a good observable to the momentum dependence of nucleon effective mass splitting.By comparing our calculations with the data,we find that the constrained L value(the slope of density dependence of symmetry energy) is about ~46 MeV when the Skyrme type interaction is considered in transport models,and the isospin diffusion data prefer to mn*>mp*,but it is not a strong constraint with deep χ2minimum.

Energy-Efficient Traffic Offloading for RSMA-Based Hybrid Satellite Terrestrial Networks with Deep Reinforcement Learning

As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.

Solar‑Driven Sustainability:Ⅲ–ⅤSemiconductor for Green Energy Production Technologies

Long-term societal prosperity depends on addressing the world’s energy and environmental problems,and photocatalysis has emerged as a viable remedy.Improving the efficiency of photocatalytic processes is fundamentally achieved by optimizing the effective utilization of solar energy and enhancing the efficient separation of photogenerated charges.It has been demonstrated that the fabrication ofⅢ–Ⅴsemiconductor-based photocatalysts is effective in increasing solar light absorption,long-term stability,large-scale production and promoting charge transfer.This focused review explores on the current developments inⅢ–Ⅴsemiconductor materials for solar-powered photocatalytic systems.The review explores on various subjects,including the advancement ofⅢ–Ⅴsemiconductors,photocatalytic mechanisms,and their uses in H2 conversion,CO_(2)reduction,environmental remediation,and photocatalytic oxidation and reduction reactions.In order to design heterostructures,the review delves into basic concepts including solar light absorption and effective charge separation.It also highlights significant advancements in green energy systems for water splitting,emphasizing the significance of establishing eco-friendly systems for CO_(2)reduction and hydrogen production.The main purpose is to produce hydrogen through sustainable and ecologically friendly energy conversion.The review intends to foster the development of greener and more sustainable energy source by encouraging researchers and developers to focus on practical applications and advancements in solar-powered photocatalysis.

Comparative analysis of energy-level splitting of Pr^(3+) doped in LiYF_4 and LiBiF_4 crystals:a complete energy matrix calculation

Based on the combination of Racah＇s group-theoretical consideration with Slater＇s wavefunction, a 91 ×91 complete energy matrix is established in tetragonal ligand field D2d for Pr3＋ ion. Thus, the Stark energy-levels of Pr3＋ ions doped separately in LiYF4 and LiBiF4 crystals are calculated, and our calculations imply that the complete energy matrix method can be used as an effective tool to calculate the energy-levels of the systems doped by rare earth ions. Besides, the influence of Pr3＋ on energy-level splitting is investigated, and the similarities and the differences between the two doped crystals are demonstrated in detail by comparing their several pairs of curves and crystal field strength quantities. We see that the energy splitting patterns are similar and the crystal field interaction of LiYF4：Pr3＋ is stronger than that of LiBiF4：Pr3＋.

Determination of spin-orbit splitting Δ_0 of valence band at Γ for gallium phosphide nanoparticles using fluorescence and infrared spectroscopes

The value of spin-orbit splitting Δ 0 of gallium phosphide （GaP） nanoparticles was determined. The information concerning the spin-orbit splitting of the valence band at Γ was acquired using fluorescence and infrared spectroscopes. Detailed investigation on the fluorescence characteristics under ultraviolet photoexcitation reveals that two doublets of emission transitions are related to the spin-orbit splitting of the valence band. The origin of two broad violet emissions, 3.00 and 3.10 eV, can be attributed to the direct transitions near the Γ point of the Brillouin zone between the Γ 1 conduction band and Γ 15 valance band, that is, Γ 6c –Γ 8v and Γ 6c –Γ 7v , respectively. The origin of two blue emissions, 2.74 and 2.64 eV, can be attributed to the indirect transitions between the X 1 conduction band and Γ 15 valance band, that is, Δ 5c –Γ 8v and Δ 5c –Γ 7v , respectively. Based on these transitions, the spin-orbit splitting Δ 0 of the GaP nanoparticles is determined as 0.10 eV. The infrared spectrum of the GaP nanoparticles shows a band at 817 cm -1 which is assigned to the transition between the Γ 7v and Γ 8v valence band maxima. It follows therefore that the spin-orbit splitting Δ 0 is 0.10 eV.

Giant Rashba-like spin-orbit splitting with distinct spin texture in two-dimensional heterostructures

Based on first-principles density functional theory calculation,we discover a novel form of spin-orbit(SO)splitting in two-dimensional(2D)heterostructures composed of a single Bi(111)bilayer stacking with a 2D semiconducting In_(2)Se_(2) or a 2D ferroelectricα-In_(2)Se_(3) layer.Such SO splitting has a Rashba-like but distinct spin texture in the valence band around the maximum,where the chirality of the spin texture reverses within the upper spin-split branch,in contrast to the conventional Rashba systems where the upper branch and lower branch have opposite chirality solely in the region below the band crossing point.The ferroelectric nature ofα-In_(2)Se_(3) further enables the tuning of the spin texture upon the reversal of the electric polarization with the application of an external electric field.Detailed analysis based on a tight-binding model reveals that such SO splitting texture results from the interplay of complex orbital characters and substrate interaction.This finding enriches the diversity of SO splitting systems and is also expected to promise for spintronic applications.

Thermospin effects in parallel coupled double quantum dots in the presence of the Rashba spin-orbit interaction and Zeeman splitting

The thermoelectric and the thermospin transport properties, including electrical conductivity, Seebeck coefficient, thermal conductivity, and thermoelectric figure of merit, of a parallel coupled double-quantum-dot Aharonov-Bohm interferometer are investigated by means of the Green function technique. The periodic Anderson model is used to describe the quantum dot system, the Rashba spin-orbit interaction and the Zeeman splitting under a magnetic field are considered. The theoretical results show the constructive contribution of the Rashba effect and the influence of the magnetic field on the thermospin effects. We also show theoretically that material with a high figure of merit can be obtained by tuning the Zeeman splitting energy only.

Light energy conversion device for photocatalyst 2.0%WO_3-TiO_2 with oxygen vacancies for water splitting

Using carbon felt, polytetrafluoroethylene latex and powder catalyst to assembly a light energy conversion device, the photocatalytic activity of catalyst 2.0%WO3-TiO2 （2%WO3 compounding TiO2） with oxygen vacancies was studied through the water splitting for O2 evolution, using a high pressure mercury lamp as the light source and Fe^3＋ as the electron acceptor in two different devices： an ordinary photolysis device with catalyst powder suspending through a magnetic stirrer and a self-assembly light energy conversion device. The results show that after 12 h irradiation, the photocatalytic activity of 2.0%WO3-TiO2 with oxygen vacancies in the self-assembly light energy conversion device is higher than that of the ordinary photolysis device, and the amount of oxygen evolution is about 12 and 9 mmol/L respectively in these two devices. After 12 h, the rates of 02 evolution are slow in each device and the photocatalyst almost loses the photoactivity in the ordinary photolysis device. So, compared with the ordinary photocatalytic device, the rate of oxygen evolution and the life time of the catalyst are improved in the self-assembly light energy conversion device.

Tailoring of Bandgap and Spin-Orbit Splitting in ZrSe_(2) with Low Substitution of Ti for Zr

Tuning the bandgap in layered transition metal dichalcogenides(TMDCs) is crucial for their versatile applications in many fields. The ternary formation is a viable method to tune the bandgap as well as other intrinsic properties of TMDCs, because the multi-elemental characteristics provide additional tunability at the atomic level and advantageously alter the physical properties of TMDCs. Herein, ternary Ti_(x)Zr_(1-x)Se_(2) single crystals were synthesized using the chemical-vapor-transport method. The changes in electronic structures of ZrSe_(2) induced by Ti substitution were revealed using angle-resolved photoemission spectroscopy. Our data show that at a low level of Ti substitution, the bandgap of Ti_(x)Zr_(1-x)Se_(2) decreases monotonically, and the electronic system undergoes a transition from a semiconducting to a metallic state without a significant variation of dispersions of valence bands. Meanwhile, the size of spin-orbit splitting dominated by Se 4p orbitals decreases with the increase of Ti doping. Our work shows a convenient way to alter the bandgap and spin-orbit coupling in TMDCs at the low level of substitution of transition metals.

Recent progress on earth abundant electrocatalysts for hydrogen evolution reaction(HER) in alkaline medium to achieve efficient water splitting–A review

Developing earth-abundant-electrocatalysts for hydrogen evolution reaction is one of the promising ways to achieve efficient water-splitting for hydrogen production(a clean chemical fuel).This paper reviews the activity,stability and durability for hydrogen evolution reaction in alkaline medium of different types of recently reported potential electrocatalysts such as Ni,Co,NiCo,Fe,Cu,W,Mo,Se,Mn.Zn,V,and metal free based earth-abundant-electrocatalysts.Further,this paper reviews the strategies used to achieve the remarkably low overpotential(including r/i0:<35mV),high long term stability(including^:100 h)and high durability(including>5000 cycles)of potential earth-abundant-electrocatalysts for hydrogen evolution reaction in alkaline medium and those are better or well comparable with the state-of-the-art,noble,Pt/C electrocatalyst.Finally,this paper summarizes the efficient strategies such as preparing porous structured materials,preparing nanostructured materials with superaerophobic surface,preparing nanostructured materials,preparing carbon composites/integrating electrocatalysts with carbon,preparing amorphous materials,preparing materials w让h oxygen vacancies/defects,preparing metal chalcogenides,preparing bimetallic/multi-metallic materials,doping metals or heteroatoms,preparing electrocatalysts with core-shell structure,decorating electrocatalysts with amines,preparing homojunction/heterojunction structured materials,preparing hollow structured materials,and preparing boronrich surface to enhance the activity,stability,and durability for HER.

High performance in Zintl thermoelectrics via reduction in crystal field splitting energy

Sustainable thermoelectric materials open an avenue of emission-free as well as fast-responding recycling of energy in terms of heat to electricity.The efficiency(η)of such conversion is primarily guided by the dimensionless thermoelectric figure of merit(zT),which depends on parameters like Seebeck coefficient(S).

Latest progress in hydrogen production from solar water splitting via photocatalysis,photoelectrochemical,and photovoltaic-photoelectrochemical solutions

Hydrogen production via solar water splitting is regarded as one of the most promising ways to utilize solar energy and has attracted more and more attention. Great progress has been made on photocatalytic water splitting for hydrogen production in the past few years. This review summarizesthe very recent progress (mainly in the last 2–3 years) on three major types of solar hydrogenproduction systems: particulate photocatalysis (PC) systems, photoelectrochemical (PEC) systems,and photovoltaic‐photoelectrochemical (PV‐PEC) hybrid systems. The solar‐to‐hydrogen (STH)conversion efficiency of PC systems has recently exceeded 1.0% using a SrTiO3:La,Rh/Au/BiVO4:Mophotocatalyst, 2.5% for PEC water splitting on a tantalum nitride photoanode, and reached 22.4%for PV‐PEC water splitting using a multi‐junction GaInP/GaAs/Ge cell and Ni electrode hybrid system.The advantages and disadvantages of these systems for hydrogen production via solar watersplitting, especially for their potential demonstration and application in the future, are briefly describedand discussed. Finally, the challenges and opportunities for solar water splitting solutions are also forecasted.

Review of the development of power system out-of-step splitting control and some thoughts on the impact of large-scale access of renewable energy

Out-of-step oscillation is a very destructive physical phenomenon in power system, which could directly cause big blackout accompanied by serious sociology-economic impacts. Out-of-step splitting control is an indispensable means, which could protect the system from major shocks of out-of-step oscillation. After years of development, it has achieved certain amount of research results. Have the existing methods been able to meet the requirements of out-of-step splitting? What improvements are needed? Under this background, this review is written. It combs the development of out-of-step splitting control technologies and analyzes the technical routes and characteristics of different methods. It points out the contradiction between rapidity and optimality is the biggest technical problem, existing in both the traditional local measurement based out-of-step splitting protection and the wide-area information based out-of-step splitting protection. It further points out that the advantages of the two types of protections can be combined with the unique physical characteristics of the out-of-step center to form a more advantageous splitting strategy. Besides, facing the fact of large-scale renewable energy access to power grid in recent years, this review also analyzes the challenges brought by it and provides some corresponding suggestions. It is hoped to provide some guidance for the subsequent research work.