The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introdu...The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introduces a triple-layer Ti-PTL with a graded porous structure and a 75%ultra-high porosity backing layer,fabricated through tape casting and roll calendering.This triple-layer PTL,composed of a microporous layer,an interlayer,and a highly porous backing layer,enhances catalyst utilization,mechanical integrity,and mass transport.Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer,significantly improving oxygen evolution reaction kinetics.Numerical simulations demonstrated that the strategically designed porous structure of the triple-layer PTL facilitates efficient oxygen transport,mitigates oxygen accumulation,and improves reactant accessibility.Electrochemical evaluations showed improved performance,achieving 127 mV reduction in voltage at 2 A cm^(-2)compared to a commercial PTL,highlighting its potential to enhance PEMWE efficiency and cost-effectiveness.展开更多
This study explores,for the first time,the influence of various C1 gases,such as methane(CH_(4)),carbon dioxide(CO_(2)),and biogas(CH4+CO_(2)),on catalytic pyrolysis of plastic waste(polypropylene)to evaluate their po...This study explores,for the first time,the influence of various C1 gases,such as methane(CH_(4)),carbon dioxide(CO_(2)),and biogas(CH4+CO_(2)),on catalytic pyrolysis of plastic waste(polypropylene)to evaluate their potential in producing aromatic hydrocarbons.Also,this study used the 0.5 wt%,1 wt%,3 wt%,and 5 wt%Ga-modified ZSM-5 catalyst and its reduction-oxidation processed catalysts owing to their promising catalytic properties.According to the results,the highest yield(39.5 wt%)of BTEX(benzene,toluene,xylene,and ethylbenzene)was achieved under CH4 over RO-GHZ(1)catalyst among all tested conditions.The reduction-oxidation process not only promotes a significant reduction of the Ga-size but also induces its diffusion inside the pore,compared to GHZ(1).This leads to the formation of highly active GaO^(+)ionic species,balancing the Lewis/Brönsted ratio,thereby accelerating the aromatization reaction.The effect of Ga loading on the RO-GHZ catalyst was also evaluated systematically,which showed a negative impact on the BTEX yield owing to the lowering in the concentration of active GaO+species.A detailed catalyst characterization supports the experimental results well.展开更多
Holographic microscopy has emerged as a vital tool in biomedicine,enabling visualization of microscopic morphological features of tissues and cells in a label-free manner.Recently,deep learning(DL)-based image reconst...Holographic microscopy has emerged as a vital tool in biomedicine,enabling visualization of microscopic morphological features of tissues and cells in a label-free manner.Recently,deep learning(DL)-based image reconstruction models have demonstrated state-of-the-art performance in holographic image reconstruction.However,their utility in practice is still severely limited,as conventional training schemes could not properly handle out-of-distribution data.Here,we leverage backpropagation operation and reparameterization of the forward propagator to enable an adaptable image reconstruction model for histopathologic inspection.Only given with a training dataset of rectum tissue images captured from a single imaging configuration,our scheme consistently shows high reconstruction performance even with the input hologram of diverse tissue types at different pathological states captured under various imaging configurations.Using the proposed adaptation technique,we show that the diagnostic features of cancerous colorectal tissues,such as dirty necrosis,captured with 5×magnification and a numerical aperture(NA)of 0.1,can be reconstructed with high accuracy,whereas a given training dataset is strictly confined to normal rectum tissues acquired under the imaging configuration of 20×magnification and an NA of 0.4.Our results suggest that the DL-based image reconstruction approaches,with sophisticated adaptation techniques,could offer an extensively generalizable solution for inverse mapping problems in imaging.展开更多
The harsh corrosive environment and sluggish oxygen evolution reaction(OER)kinetics at the anode of proton exchange membrane water electrolysis(PEMWE)cells warrant the use of excess Ir,thereby hindering large-scale in...The harsh corrosive environment and sluggish oxygen evolution reaction(OER)kinetics at the anode of proton exchange membrane water electrolysis(PEMWE)cells warrant the use of excess Ir,thereby hindering large-scale industrialization.To mitigate these issues,the present study aimed at fabricating a robust low-Ir-loading electrode via one-pot synthesis for efficient PEMWE.The pre-electrode was first prepared by alloying through the co-electrodeposition of Ir and Co,followed by the fabrication of Ir–Co oxide(Co-incorporated Ir oxide)electrodes via electrochemical dealloying.Two distinct dealloying techniques resulted in a modified valence state of Ir,and the effects of Co incorporation on the activity and stability of the OER catalysts were clarified using density functional theory(DFT)calculations,which offered theoretical insights into the reaction mechanism.While direct experimental validation of the oxygen evolution mechanism remains challenging under the current conditions,DFT-based theoretical modeling provided valuable perspectives on how Co incorporation could influence key steps in oxygen evolution catalysis.The Ir–Co oxide electrode with a selectively modulated valence state showed impressive performance with an overpotential of 258 mV at 10 mA cm^(−2),a low Tafel slope of 29.4 mV dec^(−1),and stability for 100 h at 100 mA cm^(−2)in the OER,in addition to a low overpotential of 16 mV at−10 mA cm^(−2)and high stability for 24 h in the hydrogen evolution reaction.The PEMWE cell equipped with the bifunctional Ir–Co oxide electrode as the anode and cathode exhibited outstanding performance(11.4 A cm^(−2)at 2.3 Vcell)despite having a low noble-metal content of 0.4 mgNM cm^(−2).展开更多
Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This wo...Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This work presents an innovative Pseudocapacitive Sensor.The key lies in switching the energy storage kinetics from pseudocapacitor to electrical double layer capacitor by employing the change of local pH(-log[H^(+)])in MXene-based flexible supercapacitors during bending.Pseudocapacitive sensing is observed in acidic electrolyte but absent in neutral electrolyte.Applied shearing during bending causes liquid-crystalline MXene sheets to increase in their degree of anisotropic alignment.With blocking of H+mobility due to the higher diffusion barrier,local pH increases.The electrochemical energy storage kinetics transits from Faradaic chemical protonation(intercalation)to non-Faradaic physical adsorption.We utilize the phenomenon of capacitance change due to shifting energy storage kinetics for strain sensing purposes.The developed highly sensitive Pseudocapacitive Sensors feature a remarkable gauge factor(GF)of approximately 1200,far surpassing conventional strain sensors(GF:~1 for dielectric-cap sensor).The introduction of the Pseudocapacitive Sensor represents a paradigm shift,expanding the application of pseudocapacitance from being solely confined to energy devices to the realm of multifunctional electronics.This technological leap enriches our understanding of the pseudocapacitance mechanism of MXenes,and will drive innovation in cutting-edge technology areas,including advanced robotics,implantable biomedical devices,and health monitoring systems.展开更多
A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demons...A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demonstrated by several researchers,but still have critical issues of low performance,inefficient and complex fabrication processes.Here,we present the world’s first wearable multifunctional health monitoring system based on flash-induced porous graphene(FPG).FPG was efficiently synthesized via flash lamp,resulting in a large area in four milliseconds.Moreover,to demonstrate the sensing performance of FPG,a wearable multifunctional health monitoring system was fabricated onto a single substrate.A carbon nanotube-polydimethylsiloxane(CNT-PDMS)nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing.The performance of the FPG-based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D-porous structure FPG.Finally,the FPG-based wearable multifunctional health monitoring system effectively detected motion,skin temperature,and sweat with a strain GF of 2564.38,a linear thermal response of 0.98Ω℃^(-1) under the skin temperature range,and a low ion detection limit of 10μM.展开更多
Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is ...Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.展开更多
The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)R...The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)RRs)in solid oxide elec-trolysis cells(SOECs).However,practical appli-cation of nanofiber-based electrodes faces chal-lenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte.To tackle this challenge,a novel hybrid nanofiber electrode,La_(0.6)Sr_(0.4)Co_(0.15)Fe_(0.8)Pd_(0.05)O_(3-δ)(H-LSCFP),is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique.After consecutive treatment in 100% H_(2) and CO_(2) at 700°C,LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface,enhancing CO_(2) adsorption.The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^(-2) in CO_(2) at 800°C and 1.5 V,setting a new benchmark among reported nanofiber-based electrodes.Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO_(2)RR.The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure,paving the way for further advancements and nanofiber applications in CO_(2)-SOECs.展开更多
Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,...Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR signals.Through contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal electrode.Our NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase formation.Moreover,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in LMBs.This study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.展开更多
Lithium metal batteries(LMBs)and anode-free LMBs(AFLMBs)present a solution to the need for batteries with a significantly superior theoretical energy density.However,their adoption is hindered by low Coulombic efficie...Lithium metal batteries(LMBs)and anode-free LMBs(AFLMBs)present a solution to the need for batteries with a significantly superior theoretical energy density.However,their adoption is hindered by low Coulombic efficiency(CE)and rapid capacity fading,primarily due to the formation of unstable solid electrolyte interphase(SEI)layer and Li dendrite growth as a result of uneven Li plating.Here,we report on the use of a stoichiometric Ti_(3)C_(2)T_(x)(S-Ti_(3)C_(2)T_(x))MXene coating on the copper current collector to enhance the cyclic stability of an anode-free lithium metal battery.The S-Ti_(3)C_(2)T_(x)coating provides abundant nucleation sites,thereby lowering the overpotential for Li nucleation,and promoting uniform Li plating.Additionally,the fluorine(-F)termination of S-Ti_(3)C_(2)T_(x)participates in the SEI formation,producing a LiF-rich SEI layer,vital for stabilizing the SEI and improving cycle life.Batteries equipped with S-Ti_(3)C_(2)T_(x)@Cu current collectors displayed reduced Li consumption during stable SEI formation,resulting in a significant decrease in capacity loss.AFLMBs with S-Ti_(3)C_(2)T_(x)@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm^(-2),70.9%capacity retention after 50 cycles,and an average CE of 98.19%in 100 cycles.This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.展开更多
The multidisciplinary space environment,encompassing orbital debris,cosmic radiation,and solar radiative heat,poses significant risks to spacecraft and astronauts,necessitating efficient and effective shielding soluti...The multidisciplinary space environment,encompassing orbital debris,cosmic radiation,and solar radiative heat,poses significant risks to spacecraft and astronauts,necessitating efficient and effective shielding solutions.A multi-layer shield with wide spacing has been proven to be an effective way to shield the spacecraft from space debris impact;however,due to the limited volume of the payload fairing,it was not feasible to apply a multi-layer shield to the spacecraft fuselage.Through the origami design,the shield maintains a compact form during launch and subsequently expands in outer space to enhance protection.Through geometric analysis,it has been confirmed that the deployable multi-layer space shield can occupy less space than conventional space shield structures while expanding into wider shield intervals and multiple layers.Through hypervelocity impact experiments,it was confirmed that as the bumper spacing of the multi-layer space shield expands,its ballistic performance becomes superior to conventional space structures.The deployable multi-layer space shield can reduce not only hypervelocity impacts but also solar radiative heat using the same mechanism as multi-layer insulation.Through cosmic radiation dose analysis,it has been confirmed that the multi-layer space shield is effective in cosmic radiation shielding compared to conventional space structures.展开更多
Marine accidents often result in significant losses of human life, environmental damage, and property destruction. Additionally, ships and offshore plants are large-scale and complex systems, making safety assessments...Marine accidents often result in significant losses of human life, environmental damage, and property destruction. Additionally, ships and offshore plants are large-scale and complex systems, making safety assessments challenging. However, the advent of onboard electronic systems has made it possible to monitor and respond more effectively. These new technologies can enhance safety levels while reducing the workload on crews. In this paper, authors analyze recent accidents involving ships with high structures above the water, such as car carriers or RoPax vessels, and propose preventive safety indicators to help prevent similar accidents from recurring.展开更多
At the panel session of the 3rd Global Forum on the Development of Computer Science,attendees had an opportunity to deliberate recent issues affecting computer science departments as a result of the recent growth in t...At the panel session of the 3rd Global Forum on the Development of Computer Science,attendees had an opportunity to deliberate recent issues affecting computer science departments as a result of the recent growth in the field.6 heads of university computer science departments participated in the discussions,including the moderator,Professor Andrew Yao.The first issue was how universities are managing the growing number of applicants in addition to swelling class sizes.Several approaches were suggested,including increasing faculty hiring,implementing scalable teaching tools,and working closer with other departments through degree programs that integrate computer science with other fields.The second issue was about the position and role of computer science within broader science.Participants generally agreed that all fields are increasingly relying on computer science techniques,and that effectively disseminating these techniques to others is a key to unlocking broader scientific progress.展开更多
This review provides a comprehensive overview of the progress in light-material interactions(LMIs),focusing on lasers and flash lights for energy conversion and storage applications.We discuss intricate LMI parameters...This review provides a comprehensive overview of the progress in light-material interactions(LMIs),focusing on lasers and flash lights for energy conversion and storage applications.We discuss intricate LMI parameters such as light sources,interaction time,and fluence to elucidate their importance in material processing.In addition,this study covers various light-induced photothermal and photochemical processes ranging from melting,crystallization,and ablation to doping and synthesis,which are essential for developing energy materials and devices.Finally,we present extensive energy conversion and storage applications demonstrated by LMI technologies,including energy harvesters,sensors,capacitors,and batteries.Despite the several challenges associated with LMIs,such as complex mechanisms,and high-degrees of freedom,we believe that substantial contributions and potential for the commercialization of future energy systems can be achieved by advancing optical technologies through comprehensive academic research and multidisciplinary collaborations.展开更多
Light and strong AlxCrNbVMo(x=0,0.5,and 1.0)refractory high-entropy alloys(RHEAs)were designed and fabricated via a the powder metallurgical process.The microstructure of the AlxCrNbVMo alloys consisted of a single BC...Light and strong AlxCrNbVMo(x=0,0.5,and 1.0)refractory high-entropy alloys(RHEAs)were designed and fabricated via a the powder metallurgical process.The microstructure of the AlxCrNbVMo alloys consisted of a single BCC crystalline structure with a sub-micron grain size of 2-3μm,and small amounts(<4 vol.%)of fine oxide dispersoids.This homogeneous microstructure,without chemical segregation or micropores was achieved via high-energy ball milling and spark-plasma sintering.The alloys exhibited superior mechanical properties at 25 and 1000℃compared to those of other RHEAs.Here,CrNbVMo alloy showed a yield strength of 2743 MPa at room temperature.Surprisingly,the yield strength of the CrNbVMo alloy at 1000℃was 1513 MPa.The specific yield strength of the CrNbVMo alloy was increased by 27%and 87%at 25 and 1000℃,respectively,compared to the AlMo_(0.5) NbTa_(0.5)TiZr RHEA,which exhibited so far the highest specific yield strength among the cast RHEAs.The addition of Al to CrNbVMo alloy was advantageous in reducing its reduce density to below 8.0 g/cm^(3),while the elastic modulus decreased due to the much lower elastic modulus of Al compared to that of the CrNbVMo alloy.Quantitative analysis of the strengthening contributions,showed that the solid solution strengthening,arising from a large misfit effect due to the size and modulus,and the high shear modulus of matrix,was revealed to predominant strengthening mechanism,accounting for over 50%of the yield strength of the AlxCrNbVMo RHEAs.展开更多
基金supported by the collaborative research project of Hyundai Motor Company.Also,this work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00406086,RS-2024-00338569,and RS-2024-00467191)。
文摘The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introduces a triple-layer Ti-PTL with a graded porous structure and a 75%ultra-high porosity backing layer,fabricated through tape casting and roll calendering.This triple-layer PTL,composed of a microporous layer,an interlayer,and a highly porous backing layer,enhances catalyst utilization,mechanical integrity,and mass transport.Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer,significantly improving oxygen evolution reaction kinetics.Numerical simulations demonstrated that the strategically designed porous structure of the triple-layer PTL facilitates efficient oxygen transport,mitigates oxygen accumulation,and improves reactant accessibility.Electrochemical evaluations showed improved performance,achieving 127 mV reduction in voltage at 2 A cm^(-2)compared to a commercial PTL,highlighting its potential to enhance PEMWE efficiency and cost-effectiveness.
文摘This study explores,for the first time,the influence of various C1 gases,such as methane(CH_(4)),carbon dioxide(CO_(2)),and biogas(CH4+CO_(2)),on catalytic pyrolysis of plastic waste(polypropylene)to evaluate their potential in producing aromatic hydrocarbons.Also,this study used the 0.5 wt%,1 wt%,3 wt%,and 5 wt%Ga-modified ZSM-5 catalyst and its reduction-oxidation processed catalysts owing to their promising catalytic properties.According to the results,the highest yield(39.5 wt%)of BTEX(benzene,toluene,xylene,and ethylbenzene)was achieved under CH4 over RO-GHZ(1)catalyst among all tested conditions.The reduction-oxidation process not only promotes a significant reduction of the Ga-size but also induces its diffusion inside the pore,compared to GHZ(1).This leads to the formation of highly active GaO^(+)ionic species,balancing the Lewis/Brönsted ratio,thereby accelerating the aromatization reaction.The effect of Ga loading on the RO-GHZ catalyst was also evaluated systematically,which showed a negative impact on the BTEX yield owing to the lowering in the concentration of active GaO+species.A detailed catalyst characterization supports the experimental results well.
基金supported by the Samsung Research Funding and Incubation Center of Samsung Electronics(Grant No.SRFC-IT2002-03)the Samsung Electronics Co.,Ltd.(Grant No.IO220908-02403-01)+2 种基金the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(Grant Nos.NRF-RS-2021-NR060086 and NRF-RS-2023-00251628)the Bio&Medical Technology Development Program of the National Research Foundation funded by the Korean government(MSIT)(Grant No RS-2024-00397673)the KAIST-CERAGEM Next Generation Healthcare Research Center.
文摘Holographic microscopy has emerged as a vital tool in biomedicine,enabling visualization of microscopic morphological features of tissues and cells in a label-free manner.Recently,deep learning(DL)-based image reconstruction models have demonstrated state-of-the-art performance in holographic image reconstruction.However,their utility in practice is still severely limited,as conventional training schemes could not properly handle out-of-distribution data.Here,we leverage backpropagation operation and reparameterization of the forward propagator to enable an adaptable image reconstruction model for histopathologic inspection.Only given with a training dataset of rectum tissue images captured from a single imaging configuration,our scheme consistently shows high reconstruction performance even with the input hologram of diverse tissue types at different pathological states captured under various imaging configurations.Using the proposed adaptation technique,we show that the diagnostic features of cancerous colorectal tissues,such as dirty necrosis,captured with 5×magnification and a numerical aperture(NA)of 0.1,can be reconstructed with high accuracy,whereas a given training dataset is strictly confined to normal rectum tissues acquired under the imaging configuration of 20×magnification and an NA of 0.4.Our results suggest that the DL-based image reconstruction approaches,with sophisticated adaptation techniques,could offer an extensively generalizable solution for inverse mapping problems in imaging.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(RS-2024-00340074,RS-2024-00409901,2022M3I3A1081901,and RS-2024-00413272)。
文摘The harsh corrosive environment and sluggish oxygen evolution reaction(OER)kinetics at the anode of proton exchange membrane water electrolysis(PEMWE)cells warrant the use of excess Ir,thereby hindering large-scale industrialization.To mitigate these issues,the present study aimed at fabricating a robust low-Ir-loading electrode via one-pot synthesis for efficient PEMWE.The pre-electrode was first prepared by alloying through the co-electrodeposition of Ir and Co,followed by the fabrication of Ir–Co oxide(Co-incorporated Ir oxide)electrodes via electrochemical dealloying.Two distinct dealloying techniques resulted in a modified valence state of Ir,and the effects of Co incorporation on the activity and stability of the OER catalysts were clarified using density functional theory(DFT)calculations,which offered theoretical insights into the reaction mechanism.While direct experimental validation of the oxygen evolution mechanism remains challenging under the current conditions,DFT-based theoretical modeling provided valuable perspectives on how Co incorporation could influence key steps in oxygen evolution catalysis.The Ir–Co oxide electrode with a selectively modulated valence state showed impressive performance with an overpotential of 258 mV at 10 mA cm^(−2),a low Tafel slope of 29.4 mV dec^(−1),and stability for 100 h at 100 mA cm^(−2)in the OER,in addition to a low overpotential of 16 mV at−10 mA cm^(−2)and high stability for 24 h in the hydrogen evolution reaction.The PEMWE cell equipped with the bifunctional Ir–Co oxide electrode as the anode and cathode exhibited outstanding performance(11.4 A cm^(−2)at 2.3 Vcell)despite having a low noble-metal content of 0.4 mgNM cm^(−2).
基金supported by NRF-2021M3H4A1A03047333 and NRF-2022R1F1A1075084 of the National Research Foundation(NRF)of Korea funded by the Ministry of Science and ICT,Koreasupported by Semiconductor-Secondary Battery Interfacing Platform Technology Development Project of NNFC.
文摘Extensively explored for their distinctive pseudocapacitance characteristics,MXenes,a distinguished group of 2D materials,have led to remarkable achievements,particularly in the realm of energy storage devices.This work presents an innovative Pseudocapacitive Sensor.The key lies in switching the energy storage kinetics from pseudocapacitor to electrical double layer capacitor by employing the change of local pH(-log[H^(+)])in MXene-based flexible supercapacitors during bending.Pseudocapacitive sensing is observed in acidic electrolyte but absent in neutral electrolyte.Applied shearing during bending causes liquid-crystalline MXene sheets to increase in their degree of anisotropic alignment.With blocking of H+mobility due to the higher diffusion barrier,local pH increases.The electrochemical energy storage kinetics transits from Faradaic chemical protonation(intercalation)to non-Faradaic physical adsorption.We utilize the phenomenon of capacitance change due to shifting energy storage kinetics for strain sensing purposes.The developed highly sensitive Pseudocapacitive Sensors feature a remarkable gauge factor(GF)of approximately 1200,far surpassing conventional strain sensors(GF:~1 for dielectric-cap sensor).The introduction of the Pseudocapacitive Sensor represents a paradigm shift,expanding the application of pseudocapacitance from being solely confined to energy devices to the realm of multifunctional electronics.This technological leap enriches our understanding of the pseudocapacitance mechanism of MXenes,and will drive innovation in cutting-edge technology areas,including advanced robotics,implantable biomedical devices,and health monitoring systems.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Ministry of Science,ICT and Future Planning(MSIT)(RS-2024-00408989,RS-2023-00278906,and RS-2023-00217661)the Center for Universitywide Research Facilities(CURF)at Jeonbuk National University for High-Resolution In Vivo Micro-Computed Tomography(Skyscan 1276,BRUKER).
文摘A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people.Wearable health monitoring systems were demonstrated by several researchers,but still have critical issues of low performance,inefficient and complex fabrication processes.Here,we present the world’s first wearable multifunctional health monitoring system based on flash-induced porous graphene(FPG).FPG was efficiently synthesized via flash lamp,resulting in a large area in four milliseconds.Moreover,to demonstrate the sensing performance of FPG,a wearable multifunctional health monitoring system was fabricated onto a single substrate.A carbon nanotube-polydimethylsiloxane(CNT-PDMS)nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing.The performance of the FPG-based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D-porous structure FPG.Finally,the FPG-based wearable multifunctional health monitoring system effectively detected motion,skin temperature,and sweat with a strain GF of 2564.38,a linear thermal response of 0.98Ω℃^(-1) under the skin temperature range,and a low ion detection limit of 10μM.
基金supported by the opening fund of National Key Research and Development Program of China(No.2020YFE0205300)Key Laboratory of Science and Technology on Silicon Devices,Chinese Academy of Sciences(No.KLSDTJJ2022-5)+1 种基金Chongqing Natural Science Foundation of China(No.cstc2021jcyj-msxmX1002)the Fundamental Research Funds for the Central Universities(No.AUGA5710051221).
文摘Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.
基金This work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(2019M3E6A1103944,2020R1A2C2010690).
文摘The unique characteristics of nanofibers in rational electrode design enable effec-tive utilization and maximizing material properties for achieving highly efficient and sustainable CO_(2) reduction reactions( CO_(2)RRs)in solid oxide elec-trolysis cells(SOECs).However,practical appli-cation of nanofiber-based electrodes faces chal-lenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte.To tackle this challenge,a novel hybrid nanofiber electrode,La_(0.6)Sr_(0.4)Co_(0.15)Fe_(0.8)Pd_(0.05)O_(3-δ)(H-LSCFP),is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique.After consecutive treatment in 100% H_(2) and CO_(2) at 700°C,LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface,enhancing CO_(2) adsorption.The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm^(-2) in CO_(2) at 800°C and 1.5 V,setting a new benchmark among reported nanofiber-based electrodes.Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO_(2)RR.The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure,paving the way for further advancements and nanofiber applications in CO_(2)-SOECs.
基金the Basic Research Project(C123000,C210200,C310200,&C421000)of the Korea Basic Science Institute(KBSI)funded by the Korea Ministry of Science and ICT(MSIT)the Technology Development Program to Solve Climate Changes through the National Research Foundation of Korea(NRF)funded by MSIT(NRF-2021M1A2A2038141).O.H.Han thanks to Prof.I.S.Yang at Ewha Womans University for insightful discussion.
文摘Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its progress.In this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR signals.Through contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal electrode.Our NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase formation.Moreover,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in LMBs.This study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.
基金supported by the Creative Research Initiative Program(2015R1A3A2028975)funded by the National Research Foundation of Korea(NRF)+2 种基金supported by LG energy solution-KAIST Frontier Research Laboratory(2022)the National Research Foundation of Korea(NRF)grants(MSIT,NRF-2021M3H4A1A03047333)supported(funded)by the Semiconductor-Secondary Battery Interfacing Platform Technology Development Project of NNFC
文摘Lithium metal batteries(LMBs)and anode-free LMBs(AFLMBs)present a solution to the need for batteries with a significantly superior theoretical energy density.However,their adoption is hindered by low Coulombic efficiency(CE)and rapid capacity fading,primarily due to the formation of unstable solid electrolyte interphase(SEI)layer and Li dendrite growth as a result of uneven Li plating.Here,we report on the use of a stoichiometric Ti_(3)C_(2)T_(x)(S-Ti_(3)C_(2)T_(x))MXene coating on the copper current collector to enhance the cyclic stability of an anode-free lithium metal battery.The S-Ti_(3)C_(2)T_(x)coating provides abundant nucleation sites,thereby lowering the overpotential for Li nucleation,and promoting uniform Li plating.Additionally,the fluorine(-F)termination of S-Ti_(3)C_(2)T_(x)participates in the SEI formation,producing a LiF-rich SEI layer,vital for stabilizing the SEI and improving cycle life.Batteries equipped with S-Ti_(3)C_(2)T_(x)@Cu current collectors displayed reduced Li consumption during stable SEI formation,resulting in a significant decrease in capacity loss.AFLMBs with S-Ti_(3)C_(2)T_(x)@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm^(-2),70.9%capacity retention after 50 cycles,and an average CE of 98.19%in 100 cycles.This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.
基金Supported by the National Research Foundation of South Korea(No.NRF-2021R1A4A1032783)the National Research Foundation of Korea(NRF),the Korea government(MSIT)(No.2022R1C1C1003718).
文摘The multidisciplinary space environment,encompassing orbital debris,cosmic radiation,and solar radiative heat,poses significant risks to spacecraft and astronauts,necessitating efficient and effective shielding solutions.A multi-layer shield with wide spacing has been proven to be an effective way to shield the spacecraft from space debris impact;however,due to the limited volume of the payload fairing,it was not feasible to apply a multi-layer shield to the spacecraft fuselage.Through the origami design,the shield maintains a compact form during launch and subsequently expands in outer space to enhance protection.Through geometric analysis,it has been confirmed that the deployable multi-layer space shield can occupy less space than conventional space shield structures while expanding into wider shield intervals and multiple layers.Through hypervelocity impact experiments,it was confirmed that as the bumper spacing of the multi-layer space shield expands,its ballistic performance becomes superior to conventional space structures.The deployable multi-layer space shield can reduce not only hypervelocity impacts but also solar radiative heat using the same mechanism as multi-layer insulation.Through cosmic radiation dose analysis,it has been confirmed that the multi-layer space shield is effective in cosmic radiation shielding compared to conventional space structures.
文摘Marine accidents often result in significant losses of human life, environmental damage, and property destruction. Additionally, ships and offshore plants are large-scale and complex systems, making safety assessments challenging. However, the advent of onboard electronic systems has made it possible to monitor and respond more effectively. These new technologies can enhance safety levels while reducing the workload on crews. In this paper, authors analyze recent accidents involving ships with high structures above the water, such as car carriers or RoPax vessels, and propose preventive safety indicators to help prevent similar accidents from recurring.
文摘At the panel session of the 3rd Global Forum on the Development of Computer Science,attendees had an opportunity to deliberate recent issues affecting computer science departments as a result of the recent growth in the field.6 heads of university computer science departments participated in the discussions,including the moderator,Professor Andrew Yao.The first issue was how universities are managing the growing number of applicants in addition to swelling class sizes.Several approaches were suggested,including increasing faculty hiring,implementing scalable teaching tools,and working closer with other departments through degree programs that integrate computer science with other fields.The second issue was about the position and role of computer science within broader science.Participants generally agreed that all fields are increasingly relying on computer science techniques,and that effectively disseminating these techniques to others is a key to unlocking broader scientific progress.
基金supported by the National Research Foundation of Korea(Grant number:NRF-2023R1A2C2005864)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2024-00406240)+3 种基金supported by a National Research Foundation of Korea(NRF)Grant funded by the Korean Government(MSIT)(No.2022R1A2C1003853)supported by a National Research Foundation of Korea(NRF)Grant funded by the Korean Government(MSIT)(No.RS-2023-00217661)Technology Innovation Program(RS-2022-00155961,Development of a high-efficiency drying system for carbon reduction and high-loading electrodes by a flash light source)funded by the Ministry of Trade&,Energy(MOTIE,Korea)supported by a National Research Foundation of Korea(NRF)Grant funded by the Korean Government(MSIT)(No.2022R1A2C4001497).
文摘This review provides a comprehensive overview of the progress in light-material interactions(LMIs),focusing on lasers and flash lights for energy conversion and storage applications.We discuss intricate LMI parameters such as light sources,interaction time,and fluence to elucidate their importance in material processing.In addition,this study covers various light-induced photothermal and photochemical processes ranging from melting,crystallization,and ablation to doping and synthesis,which are essential for developing energy materials and devices.Finally,we present extensive energy conversion and storage applications demonstrated by LMI technologies,including energy harvesters,sensors,capacitors,and batteries.Despite the several challenges associated with LMIs,such as complex mechanisms,and high-degrees of freedom,we believe that substantial contributions and potential for the commercialization of future energy systems can be achieved by advancing optical technologies through comprehensive academic research and multidisciplinary collaborations.
基金the National Research Foundation(NRF)grant funded by the Ministry of Science and ICT of Korea through contracts NRF-2018K2A9A1A06069970,NRF2020R1A5A6017701the Asian Office of Aerospace Research and Development(AOARD)grant funded by the Air Force Office of Scientific Research(AFOSR)through a grant FA2386-19-1-4009。
文摘Light and strong AlxCrNbVMo(x=0,0.5,and 1.0)refractory high-entropy alloys(RHEAs)were designed and fabricated via a the powder metallurgical process.The microstructure of the AlxCrNbVMo alloys consisted of a single BCC crystalline structure with a sub-micron grain size of 2-3μm,and small amounts(<4 vol.%)of fine oxide dispersoids.This homogeneous microstructure,without chemical segregation or micropores was achieved via high-energy ball milling and spark-plasma sintering.The alloys exhibited superior mechanical properties at 25 and 1000℃compared to those of other RHEAs.Here,CrNbVMo alloy showed a yield strength of 2743 MPa at room temperature.Surprisingly,the yield strength of the CrNbVMo alloy at 1000℃was 1513 MPa.The specific yield strength of the CrNbVMo alloy was increased by 27%and 87%at 25 and 1000℃,respectively,compared to the AlMo_(0.5) NbTa_(0.5)TiZr RHEA,which exhibited so far the highest specific yield strength among the cast RHEAs.The addition of Al to CrNbVMo alloy was advantageous in reducing its reduce density to below 8.0 g/cm^(3),while the elastic modulus decreased due to the much lower elastic modulus of Al compared to that of the CrNbVMo alloy.Quantitative analysis of the strengthening contributions,showed that the solid solution strengthening,arising from a large misfit effect due to the size and modulus,and the high shear modulus of matrix,was revealed to predominant strengthening mechanism,accounting for over 50%of the yield strength of the AlxCrNbVMo RHEAs.
