Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoa...Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoanodes via an interface-engineered hydrothermal growth followed by rapid thermal annealing(RTA).A TiO_(2)interfacial layer plays a crucial role in ensuring homogeneous precursor deposition,enhancing light absorption,and forming efficient heterojunctions with Sb_(2)S_(3),thereby significantly improving charge separation and transport.RTA further improves crystallinity and interfacial contact,resulting in dense and uniform Sb_(2)S_(3)films with enlarged grains and fewer defects.The optimized Sb_(2)S_(3)photoanode achieves a photocurrent density of 2.51 mA/cm^(2)at 1.23 V vs.the reversible hydrogen electrode(RHE),one of the highest reported for Sb_(2)S_(3)without additional catalysts or passivation layers.To overcome the limitations of oxygen evolution reaction(OER),we employ the iodide oxidation reaction(IOR)as an alternative,significantly lowering the overpotential and improving charge transfer kinetics.Consequently,it produces a record photocurrent density of 8.9 mA/cm^(2)at 0.54 V vs.RHE.This work highlights the synergy between TiO_(2)interfacial engineering,RTA-induced crystallization,and IOR-driven oxidation,offering a promising pathway for efficient and scalable PEC hydrogen production.展开更多
Scaled-up industrial water electrolysis equipment that can be used with abundant seawater is key for affordable hydrogen production.The search for highly stable,dynamic,and economical electrocatalysts could have a sig...Scaled-up industrial water electrolysis equipment that can be used with abundant seawater is key for affordable hydrogen production.The search for highly stable,dynamic,and economical electrocatalysts could have a significant impact on hydrogen commercialization.Herein,we prepared energy-efficient,scalable,and engineering electronic structure modulated Mn-Ni bimetal oxides(Mn_(0.25)Ni_(0.75)O)through simple hydrothermal followed by calcination method.As-optimized Mn_(0.25)Ni_(0.75)O displayed enhanced oxygen and hydrogen evolution reaction(OER and HER)performance with overpotentials of 266 and115 mV at current densities of 10 mA cm^(-2)in alkaline KOH added seawater electrolyte solution.Additionally,Mn-Ni oxide catalytic benefits were attributed to the calculated electronic configurations and Gibbs free energy for OER,and HER values were estimated using first principles calculations.In real-time practical application,we mimicked industrial operating conditions with modified seawater electrolysis using Mn_(0.25)Ni_(0.75)O‖Mn_(0.25)Ni_(0.75)O under various temperature conditions,which performs superior to the commercial IrO_(2)‖Pt-C couple.These findings demonstrate an inexpensive and facile technique for feasible large-scale hydrogen production.展开更多
The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was demonstrat...The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was demonstrated.Through the use of a novel inversion transfer technique,vertical separation of the binders from the CNTs was induced,rendering a stronger p-doping effect and thereby a higher conductivity of the CNTs.The resulting foldable devices exhibited a power conversion efficiency of 18.11%,which is the highest reported among CNT transparent electrode-based PSCs to date,and withstood more than 10,000 folding cycles at a radius of 0.5 mm,demonstrating unprecedented mechanical stability.Furthermore,solar modules were fabricated using entirely laser scribing processes to assess the potential of the solution-processable nanocarbon electrode.Notably,this is the only one to be processed entirely by the laser scribing process and to be biocompatible as well as eco-friendly among the previously reported nonindium tin oxide-based perovskite solar modules.展开更多
As global air pollution becomes increasingly severe,various types of fibrous filters have been developed to improve air filter performance.However,fibrous filters have limitations such as high packing density that gen...As global air pollution becomes increasingly severe,various types of fibrous filters have been developed to improve air filter performance.However,fibrous filters have limitations such as high packing density that generally causes high-pressure drop and ultimately deterioration in the filtration efficiency.High-pressure particulate matter precipitators are limited in terms of scope for commercialization because they require high voltage supplies and ozone generators.In this study,we develop fibrous filters with enhanced durability and improved performance using metallized microfibers decorated with metal-organic-framework(MOF)nanocrystals.Not only does the efficiency of the developed filters remain at or above 97%for 0.50-1.5μm PMs but the durability also significantly increases.In addition,using the water purification ability of the MOF,we explore the dye degradation effect of the hybrid microfibers by immersing them into Rhodamine B aqueous solution.In such an experiment the Rhodamine B aqueous solution is completely purified by the presence of the hybrid microfibers under the UV irradiation.展开更多
Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developin...Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developing highly durable ENR electrocatalysts.This study introduces defect-rich mesoporous CuO_(x) nanowires electrocatalyst synthesized using a novel solution-flame(sol-flame)hybrid method to control mesoporosity and introduce surface defects,thereby enhancing the electrochemical nitrate-toammonia production performance.We found surface defects(oxygen vacancies and Cu^(+))and unique mesoporous nanowire structure composed of tightly interconnected nanoparticles.The sol-flamesynthesized CuO_(x) nanowires(sf-CuO NWs)achieved superior ammonia yield rate(0.51 mmol h^(-1)cm^(-2)),faradaic efficiency(97.3%),and selectivity(86.2%)in 1 M KOH electrolyte(2000 ppm nitrate).This performance surpasses that of non-porous and less-defective CuO NWs and is attributed to the increased surface area and rapid electron transport facilitated by the distinctive morphology and generated defects.Theoretical calculation further suggests oxygen vacancies enhance NO_(3)^(-)adsorption on the sf-CuO NWs’surface and mitigate the competing hydrogen evolution reaction.This study outlines a strategic design and simple synthesis approach for nanowire electrocatalysts that boost the efficiency of electrochemical nitrate-to-ammonia conversion.展开更多
Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scal...Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride(PVDF)and hydrothermally synthesized ZnSnO_(3)(ZSO)cubes for PENGs.Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying.The op-timized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current,I_(sc),of 52.5 μA.A maximum power density of 50.6 μW cm-2 was ob-tained at a loading resistance of 0.4 MΩ,which matched the impedance of the PENG.Long-term tapping and bending cycles of N_(tap)=4200 and N_(bend)=600 yielded piezopotentials of 40.5 and 1.7 V,respectively.In addition,electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.展开更多
A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in...A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in a same alkaline medium.The synergistic effects caused by the combination of merits derived from NiSe_(2) and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy,thereby resulting in excellent catalytic activities and strengthened working stability.The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm^(−2) in 1.0 M KOH electrolyte.A twoelectrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm^(−2) in 1.0 M and 30 wt%KOH solution at 25℃ for overall water splitting,respectively.In addition,the solardriven water splitting process delivers a high solar-to-H_(2) conversion efficiency of∼18.4%,impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.展开更多
Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(...Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.展开更多
Green hydrogen is crucial for advancing renewable energy technologies and protecting the environment.This study introduces a controllable method for bimetallic nickel-cobalt phosphide on reduced graphene oxide on nick...Green hydrogen is crucial for advancing renewable energy technologies and protecting the environment.This study introduces a controllable method for bimetallic nickel-cobalt phosphide on reduced graphene oxide on nickel foam(NiCo_(3)P.C/NF).The material demonstrated low overpotentials of 58 and 180 mV at10 mA cm^(-2)for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in 1.0 M KOH.It achieved excellent electrochemical water-splitting performance with operating voltages of 1.54 and 2.6 V at 10 and 500 mA cm^(-2),respectively.The overall water-splitting performance of NiCo_(3).C/NF was extremely stable after 75 h of operation at 53 mA cm^(-2),retaining 98%efficiency,better than the sample Pt-C+RuO_(2),and outperforming previous reports.Density functional theory(DFT)results revealed a synergistic NiCo_(3)P.C interaction that yields nearly zero Gibbs free energy change(-0.100 eV)and upshift d-band center,the real active site at the Ni in HER,and the lowest overpotentials 0.26 V at the P active sites for OER.Furthermore,electronic charge distribution shows the maximum charge distribution between the NiCo_(3)P phase and graphene sheet heterojunction,enhancing the electrocatalyst conductivity.This combined approach offers an innovative strategy to design sustainable electrocatalysts for water s plitting.展开更多
The exploration of heterostructures composed of two-dimensional(2D)transition metal dichalcogenide(TMDc)materials has garnered significant research attention due to the distinctive properties of each individual compon...The exploration of heterostructures composed of two-dimensional(2D)transition metal dichalcogenide(TMDc)materials has garnered significant research attention due to the distinctive properties of each individual component and their phase-dependent unique properties.Using the plasma-enhanced chemical vapor deposition(PECVD)method,we analyze the fabrication of heterostructures consisting of two phases of molybdenum disulfide(MoS_(2))in four different cases.The initial hydrogen evolution reaction(HER)polarization curve indicates that the activity of the heterostructure MoS_(2)is consistent with that of the underlying MoS_(2),rather than the surface activity of the upper MoS_(2).This behavior can be attributed to the presence of Schottky barriers,which include contact resistance,which significantly hampers the efficient charge transfer at junctions between the two different phases of MoS_(2)layers and is mediated by van der Waals bonds.Remarkably,the energy barrier at the junction dissipates upon reaching a certain electrochemical potential,indicating surface activation from the top phase of MoS_(2)in the heterostructure.Notably,the 1T/2H MoS_(2)heterostructure demonstrates enhanced electrochemical stability compared to its metastable 1T-MoS_(2).This fundamental understanding paves the way for the creation of phase-controllable heterostructures through an experimentally viable PECVD,offering significant promise for a wide range of applications.展开更多
In recent years,metal halide perovskites have received significant attention as materials for next-generation optoelectronic devices owing to their excellent optoelectronic properties.The unprecedented rapid evolution...In recent years,metal halide perovskites have received significant attention as materials for next-generation optoelectronic devices owing to their excellent optoelectronic properties.The unprecedented rapid evolution in the device performance has been achieved by gaining an advanced understanding of the composition,crystal growth,and defect engineering of perovskites.As device performances approach their theoretical limits,effective optical management becomes essential for achieving higher efficiency.In this review,we discuss the status and perspectives of nano to micron-scale patterning methods for the optical management of perovskite optoelectronic devices.We initially discuss the importance of effective light harvesting and light outcoupling via optical management.Subsequently,the recent progress in various patterning/texturing techniques applied to perovskite optoelectronic devices is summarized by categorizing them into top-down and bottom-up methods.Finally,we discuss the perspectives of advanced patterning/texturing technologies for the development and commercialization of perovskite optoelectronic devices.展开更多
Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together...Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together with reduced graphene oxide(rGO)nanosheets onto Ni foil to fabricate flexible su-percapacitors.The supersonic impact facilitated the exfoliation of the rGO nanosheets,thereby increasing the surface area and adhesion of the composite particles to the substrate.The rGO nanosheets were vertically aligned during the supersonic impact and formed localized zones,enabling optimal accommodation of the ZnO/ZnMn_(2)O_(4)particles.This localization,with the addition of rGO,reduced the agglomeration of ZnO/ZnMn_(2)O_(4)particles.The molar concentration of MnSO_(4)used in the synthesis of ZnO/ZnMn_(2)O_(4)was varied from 0.05 to 0.15 mol/L to determine the optimal MnSO_(4)concentration that would result in the highest energy storage capacitance.The unique nanostructure of ZnO/ZnMn_(2)O_(4)and the self-alignment of rGO sheets facilitated a favorable environment for high energy storage capability with a specific capaci-tance of 276.3 mF·cm^(−2)at a current density of 0.5 mA·cm^(−2)and an energy density of 98.2μWh·cm^(−2)at a power density of 1600μW·cm^(−2).The width of the potential window was increased to 1.2 V,imply-ing a significant increase in the energy storage capability of the supercapacitor.Capacitance retention of 88%was achieved after 10,000 charge/discharge cycles for the supercapacitor fabricated using an optimal MnSO_(4)concentration(0.10 mol/L)during the composite synthesis.展开更多
Two-dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction(HER);however,their application is limited by a poor oxygen evolution reaction(OER)activity due to...Two-dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction(HER);however,their application is limited by a poor oxygen evolution reaction(OER)activity due to insufficient number/types of multi-integrated active sites.In this study,we report a novel bifunctional catalyst developed by simultaneous engineering of single nickel atoms(Ni_(SA)) and nickel phosphate clusters(Ni_(Pi)) to synergistically trigger surface-functionalized MoS_(2) nanosheets(NSs)resulting in high reactivities for both HER and OER.The Ni_(SA)-Ni_(Pi)/MoS_(2)NSs material exhibits a fairly Pt-like HER behavior with an overpotential of 94.0 mV and a small OER overpotential of 314.0 mV to reach 10 mA cm^(-2) in freshwater containing 1.0 M KOH.Experimental results of the catalyst are well supported by theoretical study,which reveals the significant modulation of electronic structure and enrichment of electroactive site number/types with their reasonably adjusted free adsorption energy.For evaluating practicability,the Ni_(SA)-Ni_(Pi)/MoS_(2)NSs-based electrolyzer delivers effective operation voltage of 1.62,1.52,and 1.66 V at 10 mA cm^(-2) and superior long-term stability as compared to Pt/C//RuO_(2) system in freshwater,mimic seawater,and natural seawater,respectively.The present study indicates that the catalyst is a promising candidate for the practical production of green hydrogen via water electrolysis.展开更多
The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the qualit...The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the FTS.The excessive driving frequency increases the formation of burrs.The effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.展开更多
The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storag...The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application.The NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside CC.Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode configuration.Moreover,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed cathode.Furthermore,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER.Hence,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.展开更多
Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room tem...Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.展开更多
This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is compose...This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented. The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.展开更多
The effects of temperature on a two-phase clock-driven discrete-time chaotic circuit are presented.The circuit for temperature analysis consists of two switches for sample and hold,a source follower,and a nonlinear fu...The effects of temperature on a two-phase clock-driven discrete-time chaotic circuit are presented.The circuit for temperature analysis consists of two switches for sample and hold,a source follower,and a nonlinear function for nonlinearity in the feedback.The chaotic dynamics of this circuit,such as time series,state transitions,frequency spectra bifurcation diagrams and Lyapunov exponents are analyzed as functions of the temperature.It is confirmed that the dynamics of the chaotic circuit have a temperature dependence.Further,we find that the circuit can generate discrete chaotic signals only within specific temperature regions.展开更多
A photosensitive chaotic oscillator which can be controlled with light illumination under various control voltage levels is proposed.The oscillator consists of a photodiode for the light input,clock switches and capac...A photosensitive chaotic oscillator which can be controlled with light illumination under various control voltage levels is proposed.The oscillator consists of a photodiode for the light input,clock switches and capacitors for the sample and hold function,a nonlinear function that creates an adjustable chaos map,and a voltage shifter that adjusts the output voltage for feedback.After optimizing the photodiode sub-circuit by using an available photodiode model in PC-based simulation program with integrated circuit emphasis to obtain a suitable output,the full chaotic circuit is verified with standard 0.6-μm complementary metal oxide semiconductor parameters.Chaotic dynamics are analyzed as a function of the light intensity under different control voltage levels.The time series,frequency spectra,transitions in state spaces,bifurcation diagrams and the largest Lyapunov exponent are improved.展开更多
High-purity Nd metal was recovered from waste Nd–Fe–B magnet by the molten salt electrowinning process with chemical pretreatment. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spe...High-purity Nd metal was recovered from waste Nd–Fe–B magnet by the molten salt electrowinning process with chemical pretreatment. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）, cyclic voltammetry（CV）,chronopotentiometry（CP）, and inductively coupled plasma-atomic emission spectrometer（ICP/AES） were used to characterize the deposit and electrochemical behaviors. The results show that NdF_3 is effectively synthesized from the Nd–Fe–B magnet using HCl solution and NH4F. During the chemical treatment of the waste magnet,iron impurity is eliminated as a soluble [NH4]3[FeF6]complex. Electrowinning using NdF_3 in LiF molten salt shows that Nd metal is deposited from the electrolyte onthe cathode at the reduction potentials ranging from-1.48to-1.35 V（vs. W） with the concentration change of NdF_3.The final purity of Nd metal deposit is higher than99.78 %.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant fu nded by the Korean government(MSIT)(No.RS-2024-00335976)。
文摘Antimony sulfide(Sb_(2)S_(3))is a promising material for photoelectrochemical(PEC)devices that generate green hydrogen from sunlight and water.In this study,we present a synthesis of high-performance Sb_(2)S_(3)photoanodes via an interface-engineered hydrothermal growth followed by rapid thermal annealing(RTA).A TiO_(2)interfacial layer plays a crucial role in ensuring homogeneous precursor deposition,enhancing light absorption,and forming efficient heterojunctions with Sb_(2)S_(3),thereby significantly improving charge separation and transport.RTA further improves crystallinity and interfacial contact,resulting in dense and uniform Sb_(2)S_(3)films with enlarged grains and fewer defects.The optimized Sb_(2)S_(3)photoanode achieves a photocurrent density of 2.51 mA/cm^(2)at 1.23 V vs.the reversible hydrogen electrode(RHE),one of the highest reported for Sb_(2)S_(3)without additional catalysts or passivation layers.To overcome the limitations of oxygen evolution reaction(OER),we employ the iodide oxidation reaction(IOR)as an alternative,significantly lowering the overpotential and improving charge transfer kinetics.Consequently,it produces a record photocurrent density of 8.9 mA/cm^(2)at 0.54 V vs.RHE.This work highlights the synergy between TiO_(2)interfacial engineering,RTA-induced crystallization,and IOR-driven oxidation,offering a promising pathway for efficient and scalable PEC hydrogen production.
基金supported by the GEONJI Research support programsupported by Basic Science Research through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2021R1I1A1A01050905)+1 种基金supported by grants from the Medical Research Center Program(NRF-2017R1A5A2015061)through the National Research Foundation(NRF),which is funded by the Korean government(MSIP)supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT and Future Planning(NRF-2020R1A2B5B01001458)。
文摘Scaled-up industrial water electrolysis equipment that can be used with abundant seawater is key for affordable hydrogen production.The search for highly stable,dynamic,and economical electrocatalysts could have a significant impact on hydrogen commercialization.Herein,we prepared energy-efficient,scalable,and engineering electronic structure modulated Mn-Ni bimetal oxides(Mn_(0.25)Ni_(0.75)O)through simple hydrothermal followed by calcination method.As-optimized Mn_(0.25)Ni_(0.75)O displayed enhanced oxygen and hydrogen evolution reaction(OER and HER)performance with overpotentials of 266 and115 mV at current densities of 10 mA cm^(-2)in alkaline KOH added seawater electrolyte solution.Additionally,Mn-Ni oxide catalytic benefits were attributed to the calculated electronic configurations and Gibbs free energy for OER,and HER values were estimated using first principles calculations.In real-time practical application,we mimicked industrial operating conditions with modified seawater electrolysis using Mn_(0.25)Ni_(0.75)O‖Mn_(0.25)Ni_(0.75)O under various temperature conditions,which performs superior to the commercial IrO_(2)‖Pt-C couple.These findings demonstrate an inexpensive and facile technique for feasible large-scale hydrogen production.
基金supported by the National Research Foundation of Korea funded by the Ministry of Science and ICT (MSIT),Korea (NRF-2021R1C1C1009200 and 2023R1A2C3007358)supported by the Defense Challengeable Future Technology Program of the Agency for Defense Development,Republic of Koreasupported by Technology Innovation Program of the Korea Evaluation Institute of Industrial Technology (KEIT) (20016588)funded by Ministry of Trade,Industry and Energy (MOTIE).
文摘The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was demonstrated.Through the use of a novel inversion transfer technique,vertical separation of the binders from the CNTs was induced,rendering a stronger p-doping effect and thereby a higher conductivity of the CNTs.The resulting foldable devices exhibited a power conversion efficiency of 18.11%,which is the highest reported among CNT transparent electrode-based PSCs to date,and withstood more than 10,000 folding cycles at a radius of 0.5 mm,demonstrating unprecedented mechanical stability.Furthermore,solar modules were fabricated using entirely laser scribing processes to assess the potential of the solution-processable nanocarbon electrode.Notably,this is the only one to be processed entirely by the laser scribing process and to be biocompatible as well as eco-friendly among the previously reported nonindium tin oxide-based perovskite solar modules.
基金supported by The National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2020R1A5A1018153)King Saud University,Riyadh,Saudi Arabia,for funding this work through Researchers Supporting Project number(RSP-2020/30)。
文摘As global air pollution becomes increasingly severe,various types of fibrous filters have been developed to improve air filter performance.However,fibrous filters have limitations such as high packing density that generally causes high-pressure drop and ultimately deterioration in the filtration efficiency.High-pressure particulate matter precipitators are limited in terms of scope for commercialization because they require high voltage supplies and ozone generators.In this study,we develop fibrous filters with enhanced durability and improved performance using metallized microfibers decorated with metal-organic-framework(MOF)nanocrystals.Not only does the efficiency of the developed filters remain at or above 97%for 0.50-1.5μm PMs but the durability also significantly increases.In addition,using the water purification ability of the MOF,we explore the dye degradation effect of the hybrid microfibers by immersing them into Rhodamine B aqueous solution.In such an experiment the Rhodamine B aqueous solution is completely purified by the presence of the hybrid microfibers under the UV irradiation.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.-RS-2024-00335976)。
文摘Electrochemical nitrate reduction(ENR)is an economical and eco-friendly method for converting industrial wastewater into valuable ammonia under atmospheric conditions.The main challenge lies in designing and developing highly durable ENR electrocatalysts.This study introduces defect-rich mesoporous CuO_(x) nanowires electrocatalyst synthesized using a novel solution-flame(sol-flame)hybrid method to control mesoporosity and introduce surface defects,thereby enhancing the electrochemical nitrate-toammonia production performance.We found surface defects(oxygen vacancies and Cu^(+))and unique mesoporous nanowire structure composed of tightly interconnected nanoparticles.The sol-flamesynthesized CuO_(x) nanowires(sf-CuO NWs)achieved superior ammonia yield rate(0.51 mmol h^(-1)cm^(-2)),faradaic efficiency(97.3%),and selectivity(86.2%)in 1 M KOH electrolyte(2000 ppm nitrate).This performance surpasses that of non-porous and less-defective CuO NWs and is attributed to the increased surface area and rapid electron transport facilitated by the distinctive morphology and generated defects.Theoretical calculation further suggests oxygen vacancies enhance NO_(3)^(-)adsorption on the sf-CuO NWs’surface and mitigate the competing hydrogen evolution reaction.This study outlines a strategic design and simple synthesis approach for nanowire electrocatalysts that boost the efficiency of electrochemical nitrate-to-ammonia conversion.
基金National Research Foundation of Korea(NRF)Grant funded by the Korea government(MSIT)(Nos.NRF-2020R1A5A1018153 and 2022M3J1A106422611)The authors acknowledge King Saud University,Riyadh,Saudi Arabia,for funding this work through Researchers Supporting Project number(No.RSP2023R30).
文摘Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride(PVDF)and hydrothermally synthesized ZnSnO_(3)(ZSO)cubes for PENGs.Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying.The op-timized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current,I_(sc),of 52.5 μA.A maximum power density of 50.6 μW cm-2 was ob-tained at a loading resistance of 0.4 MΩ,which matched the impedance of the PENG.Long-term tapping and bending cycles of N_(tap)=4200 and N_(bend)=600 yielded piezopotentials of 40.5 and 1.7 V,respectively.In addition,electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.
基金supported by the Regional Leading Research Center Program(2019R1A5A8080326)BRL Program(2020R1A4A1018259)through the National Research Foundation funded by the Ministry of Science and ICT of the Republic of Korea.
文摘A heterostructured electrocatalyst of small NiSe_(2) nanoparticles confined NiMoN nanorods(NiSe_(2)-NPs/NiMoN-NRs)is prepared to accelerate both the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in a same alkaline medium.The synergistic effects caused by the combination of merits derived from NiSe_(2) and NiMoN phases trigger an optimum electronic structure with high density of state at near Fermi level and enhance adsorption free energy,thereby resulting in excellent catalytic activities and strengthened working stability.The catalyst requires a low overpotential of 58 mV for HER and 241 mV for OER to reach 10 mA cm^(−2) in 1.0 M KOH electrolyte.A twoelectrode electrolyzer based on the developed catalyst shows outstanding cell voltage of 1.51 and 1.46 V to reach 10 mA cm^(−2) in 1.0 M and 30 wt%KOH solution at 25℃ for overall water splitting,respectively.In addition,the solardriven water splitting process delivers a high solar-to-H_(2) conversion efficiency of∼18.4%,impressively unveiling that the developed bifunctional catalyst is highly potential for overall water splitting to produce green hydrogen fuel.
基金Supported from the Regional Leading Research Center Program(2019R1A5A8080326)through the National Research Foundation funded by the Ministry of Science and ICT of Republic of Korea.
文摘Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.
基金supported by the Regional Leading Research Center Program(2019R1A5A8080326)funding from the Basic Science Research Program(2021R1F1A1048758,2022R1I1A1A01053248)+1 种基金the Regional Innovation Strategy(RIS)(2023RIS-008)through the National Research Foundation of Korea(NRF),funded by the Ministry of Educationsupported by the National Supercomputing Center,which provided supercomputing resources and technical support(TS-2024-RE-0039)。
文摘Green hydrogen is crucial for advancing renewable energy technologies and protecting the environment.This study introduces a controllable method for bimetallic nickel-cobalt phosphide on reduced graphene oxide on nickel foam(NiCo_(3)P.C/NF).The material demonstrated low overpotentials of 58 and 180 mV at10 mA cm^(-2)for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in 1.0 M KOH.It achieved excellent electrochemical water-splitting performance with operating voltages of 1.54 and 2.6 V at 10 and 500 mA cm^(-2),respectively.The overall water-splitting performance of NiCo_(3).C/NF was extremely stable after 75 h of operation at 53 mA cm^(-2),retaining 98%efficiency,better than the sample Pt-C+RuO_(2),and outperforming previous reports.Density functional theory(DFT)results revealed a synergistic NiCo_(3)P.C interaction that yields nearly zero Gibbs free energy change(-0.100 eV)and upshift d-band center,the real active site at the Ni in HER,and the lowest overpotentials 0.26 V at the P active sites for OER.Furthermore,electronic charge distribution shows the maximum charge distribution between the NiCo_(3)P phase and graphene sheet heterojunction,enhancing the electrocatalyst conductivity.This combined approach offers an innovative strategy to design sustainable electrocatalysts for water s plitting.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(2022R1A3B1078163 and 2022R1A4A1031182)supported by the KIMM institutional program(NK248E)and NST/KIMM+3 种基金supported by the Technology Innovation Program(or Industrial Strategic Technology Development Program)(20024772),(RS-2023-00264860)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)(1415187508)supported by the US Department of Energy,Office of Science,Office of Basic Energy Sciences,under grant no.DE-FG02-87ER13808by Northwestern University.
文摘The exploration of heterostructures composed of two-dimensional(2D)transition metal dichalcogenide(TMDc)materials has garnered significant research attention due to the distinctive properties of each individual component and their phase-dependent unique properties.Using the plasma-enhanced chemical vapor deposition(PECVD)method,we analyze the fabrication of heterostructures consisting of two phases of molybdenum disulfide(MoS_(2))in four different cases.The initial hydrogen evolution reaction(HER)polarization curve indicates that the activity of the heterostructure MoS_(2)is consistent with that of the underlying MoS_(2),rather than the surface activity of the upper MoS_(2).This behavior can be attributed to the presence of Schottky barriers,which include contact resistance,which significantly hampers the efficient charge transfer at junctions between the two different phases of MoS_(2)layers and is mediated by van der Waals bonds.Remarkably,the energy barrier at the junction dissipates upon reaching a certain electrochemical potential,indicating surface activation from the top phase of MoS_(2)in the heterostructure.Notably,the 1T/2H MoS_(2)heterostructure demonstrates enhanced electrochemical stability compared to its metastable 1T-MoS_(2).This fundamental understanding paves the way for the creation of phase-controllable heterostructures through an experimentally viable PECVD,offering significant promise for a wide range of applications.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2020R1I1A3054824)supported by the Basic Research Program through the NRF funded by the MSIT(Ministry of Science and ICT,2021R1A4A1032762)+2 种基金financial support by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(no.20213030010400)the financial support by the NRF grant funded by the MSIT under the contract numbers 2022R1C1C1011975。
文摘In recent years,metal halide perovskites have received significant attention as materials for next-generation optoelectronic devices owing to their excellent optoelectronic properties.The unprecedented rapid evolution in the device performance has been achieved by gaining an advanced understanding of the composition,crystal growth,and defect engineering of perovskites.As device performances approach their theoretical limits,effective optical management becomes essential for achieving higher efficiency.In this review,we discuss the status and perspectives of nano to micron-scale patterning methods for the optical management of perovskite optoelectronic devices.We initially discuss the importance of effective light harvesting and light outcoupling via optical management.Subsequently,the recent progress in various patterning/texturing techniques applied to perovskite optoelectronic devices is summarized by categorizing them into top-down and bottom-up methods.Finally,we discuss the perspectives of advanced patterning/texturing technologies for the development and commercialization of perovskite optoelectronic devices.
基金This work was financially supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Nos.NRF-2020R1A5A1018153,NRF-2021R1A2C2010530,and 2020K1A3A1A74114847)This research was also supported by Technology R&D Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health&Wel-fare,Republic of Korea(No.HI21C0049010021).
文摘Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together with reduced graphene oxide(rGO)nanosheets onto Ni foil to fabricate flexible su-percapacitors.The supersonic impact facilitated the exfoliation of the rGO nanosheets,thereby increasing the surface area and adhesion of the composite particles to the substrate.The rGO nanosheets were vertically aligned during the supersonic impact and formed localized zones,enabling optimal accommodation of the ZnO/ZnMn_(2)O_(4)particles.This localization,with the addition of rGO,reduced the agglomeration of ZnO/ZnMn_(2)O_(4)particles.The molar concentration of MnSO_(4)used in the synthesis of ZnO/ZnMn_(2)O_(4)was varied from 0.05 to 0.15 mol/L to determine the optimal MnSO_(4)concentration that would result in the highest energy storage capacitance.The unique nanostructure of ZnO/ZnMn_(2)O_(4)and the self-alignment of rGO sheets facilitated a favorable environment for high energy storage capability with a specific capaci-tance of 276.3 mF·cm^(−2)at a current density of 0.5 mA·cm^(−2)and an energy density of 98.2μWh·cm^(−2)at a power density of 1600μW·cm^(−2).The width of the potential window was increased to 1.2 V,imply-ing a significant increase in the energy storage capability of the supercapacitor.Capacitance retention of 88%was achieved after 10,000 charge/discharge cycles for the supercapacitor fabricated using an optimal MnSO_(4)concentration(0.10 mol/L)during the composite synthesis.
基金supported by the Regional Leading Research Center Program(2019R1A5A8080326)Basic Science Research Program(2020R1F1A1075921)BRL Program(2020R1A4A1018259)through the National Research Foundation(NRF)funded by the Ministry of Science and ICT of Republic of Korea.
文摘Two-dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction(HER);however,their application is limited by a poor oxygen evolution reaction(OER)activity due to insufficient number/types of multi-integrated active sites.In this study,we report a novel bifunctional catalyst developed by simultaneous engineering of single nickel atoms(Ni_(SA)) and nickel phosphate clusters(Ni_(Pi)) to synergistically trigger surface-functionalized MoS_(2) nanosheets(NSs)resulting in high reactivities for both HER and OER.The Ni_(SA)-Ni_(Pi)/MoS_(2)NSs material exhibits a fairly Pt-like HER behavior with an overpotential of 94.0 mV and a small OER overpotential of 314.0 mV to reach 10 mA cm^(-2) in freshwater containing 1.0 M KOH.Experimental results of the catalyst are well supported by theoretical study,which reveals the significant modulation of electronic structure and enrichment of electroactive site number/types with their reasonably adjusted free adsorption energy.For evaluating practicability,the Ni_(SA)-Ni_(Pi)/MoS_(2)NSs-based electrolyzer delivers effective operation voltage of 1.62,1.52,and 1.66 V at 10 mA cm^(-2) and superior long-term stability as compared to Pt/C//RuO_(2) system in freshwater,mimic seawater,and natural seawater,respectively.The present study indicates that the catalyst is a promising candidate for the practical production of green hydrogen via water electrolysis.
基金Project(2010-0008-277)supported by NCRC(National Core Research Center)Program of the Ministry of Education,Science and Technology,KoreaProject supported by"Development of Micro Feature Machining System on Large Surface and Core Technologies for Measurement & Inspection"of Ministry of Knowledge Economy,Korea
文摘The development of the fast tool servo (FTS) for precision machining was investigated.The micron machining performance of a piezoelectric-assisted FTS on copper alloy was evaluated.The results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the FTS.The excessive driving frequency increases the formation of burrs.The effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(2021R1A4A2000934).
文摘The metal-organic framework(MOF)derived Ni–Co–C–N composite alloys(NiCCZ)were“embedded”inside the carbon cloth(CC)strands as opposed to the popular idea of growing them upward to realize ultrastable energy storage and conversion application.The NiCCZ was then oxygen functionalized,facilitating the next step of stoichiometric sulfur anion diffusion during hydrothermal sulfurization,generating a flower-like metal hydroxysulfide structure(NiCCZOS)with strong partial implantation inside CC.Thus obtained NiCCZOS shows an excellent capacity when tested as a supercapacitor electrode in a three-electrode configuration.Moreover,when paired with the biomass-derived nitrogen-rich activated carbon,the asymmetric supercapacitor device shows almost 100%capacity retention even after 45,000 charge–discharge cycles with remarkable energy density(59.4 Wh kg^(-1)/263.8μWh cm^(–2))owing to a uniquely designed cathode.Furthermore,the same electrode performed as an excellent bifunctional water-splitting electrocatalyst with an overpotential of 271 mV for oxygen evolution reaction(OER)and 168.4 mV for hydrogen evolution reaction(HER)at 10 mA cm−2 current density along with 30 h of unhinged chronopotentiometric stability performance for both HER and OER.Hence,a unique metal chalcogenide composite electrode/substrate configuration has been proposed as a highly stable electrode material for flexible energy storage and conversion applications.
基金supported by NCRC(National Core Research Center)program of the Ministry of Education,Science and Technology(2010-0008-277)"Development of next generation multi-functional machining systems for eco/bio components" project of ministry of knowledge economy
文摘Ultra-precision diamond machining with piezoelectric-assisted fast tool servo (FTS) was used to produce various free-form surfaces.A low cost,rapid and large area fabrication of uniform hydrophobic surface at room temperature which transfers the FTS fabricated sinusoidal grid surface to the flat film with UV-moulding process was described.A piezoelectric-assisted FTS with high band width of 2 kHz,travel range up to 16 μm and the compact mechanism structure was designed for the sinusoidal grid surface machining and the dynamic performance testing of FTS was described in detail.Machining results indicate that the dimensions of sinusoidal grid change with the variation of the FTS machining condition.Wetting properties of UV-moulded surface were evaluated,the best contact angle was measured to be 120.5° on the sinusoidal grid surface with profile wavelength of 350 μm and peak-to-valley amplitude of about 16 μm.
基金Project supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant No.2011-0011698)
文摘This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented. The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.
基金Supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(2012-0002777).
文摘The effects of temperature on a two-phase clock-driven discrete-time chaotic circuit are presented.The circuit for temperature analysis consists of two switches for sample and hold,a source follower,and a nonlinear function for nonlinearity in the feedback.The chaotic dynamics of this circuit,such as time series,state transitions,frequency spectra bifurcation diagrams and Lyapunov exponents are analyzed as functions of the temperature.It is confirmed that the dynamics of the chaotic circuit have a temperature dependence.Further,we find that the circuit can generate discrete chaotic signals only within specific temperature regions.
基金Supported by the 2013 Research Fund of Inje University.
文摘A photosensitive chaotic oscillator which can be controlled with light illumination under various control voltage levels is proposed.The oscillator consists of a photodiode for the light input,clock switches and capacitors for the sample and hold function,a nonlinear function that creates an adjustable chaos map,and a voltage shifter that adjusts the output voltage for feedback.After optimizing the photodiode sub-circuit by using an available photodiode model in PC-based simulation program with integrated circuit emphasis to obtain a suitable output,the full chaotic circuit is verified with standard 0.6-μm complementary metal oxide semiconductor parameters.Chaotic dynamics are analyzed as a function of the light intensity under different control voltage levels.The time series,frequency spectra,transitions in state spaces,bifurcation diagrams and the largest Lyapunov exponent are improved.
基金financially supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) of the Korea Government Ministry of Knowledge Economy (No. 20122010300041)the National Research Foundation of Korea (No. 2011-0091839)
文摘High-purity Nd metal was recovered from waste Nd–Fe–B magnet by the molten salt electrowinning process with chemical pretreatment. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）, cyclic voltammetry（CV）,chronopotentiometry（CP）, and inductively coupled plasma-atomic emission spectrometer（ICP/AES） were used to characterize the deposit and electrochemical behaviors. The results show that NdF_3 is effectively synthesized from the Nd–Fe–B magnet using HCl solution and NH4F. During the chemical treatment of the waste magnet,iron impurity is eliminated as a soluble [NH4]3[FeF6]complex. Electrowinning using NdF_3 in LiF molten salt shows that Nd metal is deposited from the electrolyte onthe cathode at the reduction potentials ranging from-1.48to-1.35 V（vs. W） with the concentration change of NdF_3.The final purity of Nd metal deposit is higher than99.78 %.
