BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfacto...BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.展开更多
Although bismuth vanadate(BiVO4)has been promising as photoanode material for photoelectrochemical water splitting,its charge recombination issue by short charge diffusion length has led to various studies about heter...Although bismuth vanadate(BiVO4)has been promising as photoanode material for photoelectrochemical water splitting,its charge recombination issue by short charge diffusion length has led to various studies about heterostructure photoanodes.As a hole blocking layer of BiVO4,titanium dioxide(TiO_(2)) has been considered unsuitable because of its relatively positive valence band edge and low electrical conductivity.Herein,a crystal facet engineering of TiO_(2) nanostructures is proposed to control band structures for the hole blocking layer of BiVO4 nanodots.We design two types of TiO_(2) nanostructures,which are nanorods(NRs)and nanoflowers(NFs)with different(001)and(110)crystal facets,respectively,and fabricate BiVO4/TiO_(2) heterostructure photoanodes.The BiVO4/TiO_(2) NFs showed 4.8 times higher photocurrent density than the BiVO4/TiO_(2) NRs.Transient decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination,which is originated from the formation of type II band alignment between BiVO4 nanodots and TiO_(2) NFs.This work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes.展开更多
Characterizing the kerogen-hosted pore structures is essential to understand the adsorption,transport and storage potential in organic-rich shale reservoirs.In this paper,we first separated the organic matter(kerogen)...Characterizing the kerogen-hosted pore structures is essential to understand the adsorption,transport and storage potential in organic-rich shale reservoirs.In this paper,we first separated the organic matter(kerogen)from the mineral matrix in four different shale samples of the Bakken Formation with different thermal maturities and then analyzed their chemical compositions using the wide-angle X-ray scattering(WAXS)method.Next,we acquired small-angle X-ray scattering(SAXS)to characterize the structure of the organic matter and see how these two will relate.The WAXS results showed that the isolated kerogens have high purity(free of inorganic minerals)and retain different chemical compositions.Moreover,SAXS analysis revealed that the isolated kerogens have similar radius of gyration(R_(g))which is around 90Åand the molecules are in the compact mode.Based on the pore size distribution analysis from the SAXS data,two main peaks were found in all of these four samples with one peak less than 40Åand the other one larger than 1000Å.Also,the TEM images revealed that Sample 1 is abundant in pores with sizes around 20 nm while Sample 2 does not have pores of that size,which agrees with the results from the pore size distribution that was obtained from the SAXS method.Ultimately,this study exhibits how different analytical instruments can provide us with useful information from complex structures of geomaterials.展开更多
Transition metal phosphides(TMPs)and transition metal dichalcogenides(TMDs)have been widely investigated as photoelectrochemical(PEC)catalysts for hydrogen evolution reaction(HER).Using high-temperature processes to g...Transition metal phosphides(TMPs)and transition metal dichalcogenides(TMDs)have been widely investigated as photoelectrochemical(PEC)catalysts for hydrogen evolution reaction(HER).Using high-temperature processes to get crystallized compounds with large-area uniformity,it is still challenging to directly synthesize these catalysts on silicon photocathodes due to chemical incompatibility at the heterointerface.Here,a graphene interlayer is applied between p-Si and MoP nanorods to enable fully engineered interfaces without forming a metallic secondary compound that absorbs a parasitic light and provides an inefficient electron path for hydrogen evolution.Furthermore,the graphene facilitates the photogenerated electrons to rapidly transfer by creating Mo-O-C covalent bondings and energetically favorable band bending.With a bridging role of graphene,numerous active sites and anti-reflectance of MoP nanorods lead to significantly improved PEC-HER performance with a high photocurrent density of 21.8 mA cm−2 at 0 V versus RHE and high stability.Besides,low dependence on pH and temperature is observed with MoP nanorods incorporated photocathodes,which is desirable for practical use as a part of PEC cells.These results indicate that the direct synthesis of TMPs and TMDs enabled by graphene interlayer is a new promising way to fabricate Si-based photocathodes with high-quality interfaces and superior HER performance.展开更多
To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Ach...To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Achieving optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis processes.Scanning electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical insights.It possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface topography.This review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage systems.Commencing with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.展开更多
To attain a circular carbon economy and resolve CO_(2) electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic a...To attain a circular carbon economy and resolve CO_(2) electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic activity.Among SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal aggregation.This study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100% for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h^(−1),validating their intrinsic catalytic potential.These results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during pyrolysis.Furthermore,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*) preadsorbed sites as initial states was possible and provided valuable insights.展开更多
The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen pro...The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal catalysts.However,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic conductivity.To address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic conductivity.Notably,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic catalysts.Although the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC method.The review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange groups.We systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the membrane.This review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications.展开更多
Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power consumption.However,despite thes...Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power consumption.However,despite these benefits,challenges still exist such as a limited range of detectable gases and slow response.In this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power consumption.The optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain simulation.Additionally,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)NPs.The noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and C2H5OH.Real-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.展开更多
Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film...Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room temperature.During the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi domains.Lattice mismatch between both domains induces biaxial strain at the interfaces.Density functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to HCOOH.Together with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to HCOOH.This work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.展开更多
The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to ac...The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to achieve a self-standing electrode,composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters(ACP/Ru_(SAC+C))via acid activation,immersion,and high-temperature pyrolysis.Ab initio molecular dynamics(AIMD)calculations are employed to gain a more profound understanding of the impact of acid activation on carbon paper.Furthermore,the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy(AC-STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS).Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect,tuning the electronic structure and thereby significantly enhancing their catalytic performance.Notably,the ACP/Ru_(SAC+C)exhibits a remarkable turnover frequency(TOF)of 18 s^(−1)and an exceptional mass activity(MA)of 2.2 A mg^(−1),surpassing the performance of conventional Pt electrodes.The self-standing electrode,featuring harmoniously coexisting Ru states,stands out as a prospective choice for advancing HER catalysts,enhancing energy efficiency,productivity,and selectivity.展开更多
Two-dimensional(2D)transition metal chalcogenides(TMC)and their heterostructures are appealing as building blocks in a wide range of electronic and optoelectronic devices,particularly futuristic memristive and synapti...Two-dimensional(2D)transition metal chalcogenides(TMC)and their heterostructures are appealing as building blocks in a wide range of electronic and optoelectronic devices,particularly futuristic memristive and synaptic devices for brain-inspired neuromorphic computing systems.The distinct properties such as high durability,electrical and optical tunability,clean surface,flexibility,and LEGO-staking capability enable simple fabrication with high integration density,energy-efficient operation,and high scalability.This review provides a thorough examination of high-performance memristors based on 2D TMCs for neuromorphic computing applications,including the promise of 2D TMC materials and heterostructures,as well as the state-of-the-art demonstration of memristive devices.The challenges and future prospects for the development of these emerging materials and devices are also discussed.The purpose of this review is to provide an outlook on the fabrication and characterization of neuromorphic memristors based on 2D TMCs.展开更多
Recently,artificial synapses involving an electrochemical reaction of Li-ion have been attributed to have remarkable synaptic properties.Three-terminal synaptic transistors utilizing Li-ion intercalation exhibits reli...Recently,artificial synapses involving an electrochemical reaction of Li-ion have been attributed to have remarkable synaptic properties.Three-terminal synaptic transistors utilizing Li-ion intercalation exhibits reliable synaptic characteristics by exploiting the advantage of nondistributed weight updates owing to stable ion migrations.However,the three-terminal configurations with large and complex structures impede the crossbar array implementation required for hardware neuromorphic systems.Meanwhile,achieving adequate synaptic performances through effective Li-ion intercalation in vertical two-terminal synaptic devices for array integration remains challenging.Here,two-terminal Au/LixCoO_(2)/Pt artificial synapses are proposed with the potential for practical implementation of hardware neural networks.The Au/LixCoO_(2)/Pt devices demonstrated extraordinary neuromorphic behaviors based on a progressive dearth of Li in LixCoO_(2)films.The intercalation and deintercalation of Li-ion inside the films are precisely controlled over the weight control spike,resulting in improved weight control functionality.Various types of synaptic plasticity were imitated and assessed in terms of key factors such as nonlinearity,symmetricity,and dynamic range.Notably,the LixCoO_(2)-based neuromorphic system outperformed three-terminal synaptic transistors in simulations of convolutional neural networks and multilayer perceptrons due to the high linearity and low programming error.These impressive performances suggest the vertical two-terminal Au/LixCoO_(2)/Pt artificial synapses as promising candidates for hardware neural networks.展开更多
There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attra...There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion reactions.Its versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and functionalization.Here,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.展开更多
Cancer immunotherapy has been intensively investigated in both preclinical and clinical studies.Whereas chemotherapies use cytotoxic drugs to kill tumor cells,cancer immunotherapy is based on the ability of the immune...Cancer immunotherapy has been intensively investigated in both preclinical and clinical studies.Whereas chemotherapies use cytotoxic drugs to kill tumor cells,cancer immunotherapy is based on the ability of the immune system to fight cancer.Tumors are intimately associated with the immune system:they can suppress the immune response and/or control immune cells to support tumor growth.Immunotherapy has yielded promising results in clinical practice,but some patients show limited responses.This may reflect the complexities of the relationship between a tumor and the immune system.In an effort to improve the current immunotherapies,researchers have exploited nanomaterials in creating new strategies to cure tumors via modulation of the immune system in tumor tissues.Although extensive studies have examined the use of immune checkpoint-based immunotherapy,rather less work has focused on manipulating the innate immune cells.This review examines the recent approaches and challenges in the use of nanomaterials to modulate innate immune cells.展开更多
The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar-driven water splitting.Here,we first introduce indium oxide(In_(2)O_(3))nanorods(NRs)as a novel electron tr...The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar-driven water splitting.Here,we first introduce indium oxide(In_(2)O_(3))nanorods(NRs)as a novel electron transport layer for bismuth vanadate(BiVO_(4))with a short charge diffusion length.In_(2)O_(3)NRs reinforce the electron transport and hole blocking of BiVO_(4),surpassing the state-of-the-art photoelectrochemical performances of BiVO_(4)-based photoanodes.Also,a tannin-nickel-iron complex(TANF)is used as an oxygen evolution catalyst to speed up the reaction kinetics.The final TANF/BiVO_(4)/In_(2)O_(3)NR photoanode generates photocurrent densities of 7.1 mAcm^(−2) in sulfite oxidation and 4.2 mA cm^(−2) in water oxidation at 1.23 V versus the reversible hydrogen electrode.Furthermore,the“artificial leaf,”which is a tandem cell with a perovskite/silicon solar cell,shows a solar-to-hydrogen conversion efficiency of 6.2%for unbiased solar water splitting.We reveal significant advances in the photoactivity of TANF/BiVO_(4)/In_(2)O_(3)NRs from the tailored nanostructure and band structure for charge dynamics.展开更多
The original version of this article,unfortunately,contained some mistakes and unintentional wrong description of Fig.6 and the caption of Figs.9,10.The correct version of Fig.6 is below.The mentioned figure name for ...The original version of this article,unfortunately,contained some mistakes and unintentional wrong description of Fig.6 and the caption of Figs.9,10.The correct version of Fig.6 is below.The mentioned figure name for the Fig.6 on the manuscript should be updated.In 2D vdW synaptic devices,the length of the tunneling barrier can be increased or decreased on the trapped or detrapped electrons.Kumar et al.reported memristive and neuromorphic devices composed of vertically grown WS2 layer and ZnO(Fig.6e)[149].The interlayer separation between WS2 and ZnO layers serves as an effective porous medium allowing the ZnO to grow with defects.The interfacial region of ZnO,the very contiguous to WS2 layer.展开更多
We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index o...We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index of a CaF2 nanograss （NG） layer on a glass substrate, deposited by glancing angle vapor deposition, is 1.04 at 500 nm, which is the second-lowest value ever reported so far. The fluorinated NG layer gives rise to a high water contact angle （〉150°） and very efficient cleaning out of dust with water drops. Using the dual functionalities of the SNGC glass, we demonstrate superhydrophobic and antireflective organic photovoltaic cells with excellent power conversion efficiency.展开更多
Although lithium-air batteries(LABs)are considered the promising alternative of existing lithium–ion batteries owing to their high energy density of 11680 W h kg^(-1),their practical applications are limited by the t...Although lithium-air batteries(LABs)are considered the promising alternative of existing lithium–ion batteries owing to their high energy density of 11680 W h kg^(-1),their practical applications are limited by the technical issues,such as unstable solid electrolyte interface and dendrite formation from metal anode and insufficient bifunctional activities and durability from cathode catalyst.In order to resolve these bottlenecks,carbon nanostructures have been investigated owing to their high surface area,excellent electrical conductivity,electrochemical stability,and various modification chemistries.Herein,we comprehensively review a recent progress on the design of carbon nanostructures for their applications into metal hosts,protection layers,and bifunctional electrocatalysts of LABs.The correlation between the crystalline,electronic,porous,and chemical structures and the electrochemical properties of carbon nanomaterials are discussed depending on their classification and characteristics.Various chemical modifications,such as morphological control,hierarchical architecturing,heteroatom incorporation,and the formation of composites,for the improved electrochemical performances of anode and cathode will be also addressed.Furthermore,we deal with the perspectives for the ongoing obstruction and future guidance.展开更多
An electronic nose(e-nose)is a device that can detect and recognize odors and flavors using a sensor array.It has received considerable interest in the past decade because it is required in several areas such as healt...An electronic nose(e-nose)is a device that can detect and recognize odors and flavors using a sensor array.It has received considerable interest in the past decade because it is required in several areas such as health care,environmental monitoring,industrial applications,automobile,food storage,and military.However,there are still obstacles in developing a portable e-nose that can be used for a wide variety of applications.For practical applications of an e-nose,it is necessary to collect a massive amount of data from various sensing materials that can transduce interactions with molecules reliably and analyze them via pattern recognition.In addition,the possibility of miniaturizing the e-nose and operating it with low power consumption should be considered.Moreover,it should work efficiently over a long period of time.To satisfy these requirements,several different chemoresistive material platforms including metal oxides,organics such as polymers and carbonbased materials,and two-dimensional materials were investigated as sensor elements for an e-nose.As an individual material has limited selectivity,there is a continuing effort to improve the selectivity and gas sensing properties through surface decoration and compositional and structural variations.To produce a reliable e-nose,which can be used for practical applications,researches in various fields have to be harmonized.This paper reviews the progress of research on e-noses based on a chemoresistive gas sensor array and discusses the inherent challenges and potential solutions.展开更多
基金supported by the program of Future Hydrogen Original Technology Development(2021M3I3A1084747),through the National Research Foundation of Korea(NRF)funded by the Korean government(Ministry of Science and ICT(MSIT))by the NRF grant funded by the Korea government(MSIT)(No.2020R1A2C1005590)。
文摘BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical applications.However,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance.To address this,various modifications have been attempted,including the use of ferroelectric materials.Ferroelectric materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole pairs.In this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of BFO.The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination.As a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)analysis.These results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(MSIT)(2021R1A2B5B03001851)the NRF Grant funded by the Korean government MSIT(2021M3H4A1A03057403).M.G.L.acknowledges the Basic Science Research Program through the NRF funded by the Ministry of Education(2021R1A6A3A03039988).J.W.Y.acknowledges the Basic Science Research Program through the NRF funded by the Ministry of Education(2021R1A6A3A13046700).
文摘Although bismuth vanadate(BiVO4)has been promising as photoanode material for photoelectrochemical water splitting,its charge recombination issue by short charge diffusion length has led to various studies about heterostructure photoanodes.As a hole blocking layer of BiVO4,titanium dioxide(TiO_(2)) has been considered unsuitable because of its relatively positive valence band edge and low electrical conductivity.Herein,a crystal facet engineering of TiO_(2) nanostructures is proposed to control band structures for the hole blocking layer of BiVO4 nanodots.We design two types of TiO_(2) nanostructures,which are nanorods(NRs)and nanoflowers(NFs)with different(001)and(110)crystal facets,respectively,and fabricate BiVO4/TiO_(2) heterostructure photoanodes.The BiVO4/TiO_(2) NFs showed 4.8 times higher photocurrent density than the BiVO4/TiO_(2) NRs.Transient decay time analysis and time-resolved photoluminescence reveal the enhancement is attributed to the reduced charge recombination,which is originated from the formation of type II band alignment between BiVO4 nanodots and TiO_(2) NFs.This work provides not only new insights into the interplay between crystal facets and band structures but also important steps for the design of highly efficient photoelectrodes.
文摘Characterizing the kerogen-hosted pore structures is essential to understand the adsorption,transport and storage potential in organic-rich shale reservoirs.In this paper,we first separated the organic matter(kerogen)from the mineral matrix in four different shale samples of the Bakken Formation with different thermal maturities and then analyzed their chemical compositions using the wide-angle X-ray scattering(WAXS)method.Next,we acquired small-angle X-ray scattering(SAXS)to characterize the structure of the organic matter and see how these two will relate.The WAXS results showed that the isolated kerogens have high purity(free of inorganic minerals)and retain different chemical compositions.Moreover,SAXS analysis revealed that the isolated kerogens have similar radius of gyration(R_(g))which is around 90Åand the molecules are in the compact mode.Based on the pore size distribution analysis from the SAXS data,two main peaks were found in all of these four samples with one peak less than 40Åand the other one larger than 1000Å.Also,the TEM images revealed that Sample 1 is abundant in pores with sizes around 20 nm while Sample 2 does not have pores of that size,which agrees with the results from the pore size distribution that was obtained from the SAXS method.Ultimately,this study exhibits how different analytical instruments can provide us with useful information from complex structures of geomaterials.
基金financially supported by the Basic Science Research Program(2017R1A2B3009135)the Korean government MSIT(2019M3E6A1103818)+2 种基金the Basic Research Laboratory Program(2018R1A4A1022647)the Future Material Discovery Program(2018M3D1A1058793)through the National Research Foundation of KoreaKOREA HYDRO&NUCLEAR POWER CO.,LTD.(No.2018-Tech-21)。
文摘Transition metal phosphides(TMPs)and transition metal dichalcogenides(TMDs)have been widely investigated as photoelectrochemical(PEC)catalysts for hydrogen evolution reaction(HER).Using high-temperature processes to get crystallized compounds with large-area uniformity,it is still challenging to directly synthesize these catalysts on silicon photocathodes due to chemical incompatibility at the heterointerface.Here,a graphene interlayer is applied between p-Si and MoP nanorods to enable fully engineered interfaces without forming a metallic secondary compound that absorbs a parasitic light and provides an inefficient electron path for hydrogen evolution.Furthermore,the graphene facilitates the photogenerated electrons to rapidly transfer by creating Mo-O-C covalent bondings and energetically favorable band bending.With a bridging role of graphene,numerous active sites and anti-reflectance of MoP nanorods lead to significantly improved PEC-HER performance with a high photocurrent density of 21.8 mA cm−2 at 0 V versus RHE and high stability.Besides,low dependence on pH and temperature is observed with MoP nanorods incorporated photocathodes,which is desirable for practical use as a part of PEC cells.These results indicate that the direct synthesis of TMPs and TMDs enabled by graphene interlayer is a new promising way to fabricate Si-based photocathodes with high-quality interfaces and superior HER performance.
基金supported by a characterization platform for advanced materials funded by the Korea Research Institute of Standards and Science(KRISS-2023-GP2023-0014)the KRISS(Korea Research Institute of Standards and Science)MPI Lab.program。
文摘To address climate change and promote environmental sustainability,electrochemical energy conversion and storage systems emerge as promising alternative to fossil fuels,catering to the escalating demand for energy.Achieving optimal energy efficiency and cost competitiveness in these systems requires the strategic design of electrocatalysts,coupled with a thorough comprehension of the underlying mechanisms and degradation behavior occurring during the electrocatalysis processes.Scanning electrochemical microscopy(SECM),an analytical technique for studying surface electrochemically,stands out as a powerful tool offering electrochemical insights.It possesses remarkable spatiotemporal resolution,enabling the visualization of the localized electrochemical activity and surface topography.This review compiles crucial research findings and recent breakthroughs in electrocatalytic processes utilizing the SECM methodology,specifically focusing on applications in electrolysis,fuel cells,and metal–oxygen batteries within the realm of energy conversion and storage systems.Commencing with an overview of each energy system,the review introduces the fundamental principles of SECM,and aiming to provide new perspectives and broadening the scope of applied research by describing the major research categories within SECM.
基金National Research Foundation of Korea(NRF),Grant/Award Numbers:2021R1A4A3027878,RS‐2023‐00209139,2015M3D3A1A01064929Korea Institute of Energy Technology&Energy(MOTIE)of the Republic of Korea,Grant/Award Number:20212010100040。
文摘To attain a circular carbon economy and resolve CO_(2) electroreduction technology obstacles,single‐atom catalysts(SACs)have emerged as a logical option for electrocatalysis because of their extraordinary catalytic activity.Among SACs,metal–organic frameworks(MOFs)have been recognized as promising support materials because of their exceptional ability to prevent metal aggregation.This study shows that atomically dispersed Ni single atoms on a precisely engineered MOF nanosheet display a high Faradaic efficiency of approximately 100% for CO formation in H‐cell and three‐compartment microfluidic flow‐cell reactors and an excellent turnover frequency of 23,699 h^(−1),validating their intrinsic catalytic potential.These results suggest that crystallographic variations affect the abundant vacancy sites on the MOF nanosheets,which are linked to the evaporation of Zn‐containing organic linkers during pyrolysis.Furthermore,using X‐ray absorption spectroscopy and density functional theory calculations,a comprehensive investigation of the unsaturated atomic coordination environments and the underlying mechanism involving CO^(*) preadsorbed sites as initial states was possible and provided valuable insights.
基金supported by the KRISS(Korea Research Institute of Standards and Science)MPI Lab.program。
文摘The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal catalysts.However,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic conductivity.To address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic conductivity.Notably,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic catalysts.Although the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC method.The review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange groups.We systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the membrane.This review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications.
基金supported by the Nano&Material Technology Development Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(RS-2024-00405016)supported by“Cooperative Research Program for Agriculture Science and Technology Development(Project No.PJ01706703)”Rural Development Administration,Republic of Korea.The Inter-University Semiconductor Research Center and Institute of Engineering Research at Seoul National University provided research facilities for this work.
文摘Micro-light-emitting diodes(μLEDs)have gained significant interest as an activation source for gas sensors owing to their advantages,including room temperature operation and low power consumption.However,despite these benefits,challenges still exist such as a limited range of detectable gases and slow response.In this study,we present a blueμLED-integrated light-activated gas sensor array based on SnO_(2)nanoparticles(NPs)that exhibit excellent sensitivity,tunable selectivity,and rapid detection with micro-watt level power consumption.The optimal power forμLED is observed at the highest gas response,supported by finite-difference time-domain simulation.Additionally,we first report the visible light-activated selective detection of reducing gases using noble metal-decorated SnO_(2)NPs.The noble metals induce catalytic interaction with reducing gases,clearly distinguishing NH3,H2,and C2H5OH.Real-time gas monitoring based on a fully hardwareimplemented light-activated sensing array was demonstrated,opening up new avenues for advancements in light-activated electronic nose technologies.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(20212010100040)in part by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(2019R1A2C1091158)in part by Brain Korea 21 FOUR project for Education and Research Center for Future Materials(F21YY7105002)
文摘Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room temperature.During the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi domains.Lattice mismatch between both domains induces biaxial strain at the interfaces.Density functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to HCOOH.Together with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to HCOOH.This work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.
基金supported by the National Research Foundation of Korea(NRF),funded by the Korean government(2022M3H4A1A01012712,2022M3H4A1A04096380)S.Back acknowledges the support from the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2016R1A6A1A03012845)and generous supercomputing time from KISTI.
文摘The development of cost-effective,highly efficient,and durable electrocatalysts has been a paramount pursuit for advancing the hydrogen evolution reaction(HER).Herein,a simplified synthesis protocol was designed to achieve a self-standing electrode,composed of activated carbon paper embedded with Ru single-atom catalysts and Ru nanoclusters(ACP/Ru_(SAC+C))via acid activation,immersion,and high-temperature pyrolysis.Ab initio molecular dynamics(AIMD)calculations are employed to gain a more profound understanding of the impact of acid activation on carbon paper.Furthermore,the coexistence states of the Ru atoms are confirmed via aberration-corrected scanning transmission electron microscopy(AC-STEM),X-ray photoelectron spectroscopy(XPS),and X-ray absorption spectroscopy(XAS).Experimental measurements and theoretical calculations reveal that introducing a Ru single-atom site adjacent to the Ru nanoclusters induces a synergistic effect,tuning the electronic structure and thereby significantly enhancing their catalytic performance.Notably,the ACP/Ru_(SAC+C)exhibits a remarkable turnover frequency(TOF)of 18 s^(−1)and an exceptional mass activity(MA)of 2.2 A mg^(−1),surpassing the performance of conventional Pt electrodes.The self-standing electrode,featuring harmoniously coexisting Ru states,stands out as a prospective choice for advancing HER catalysts,enhancing energy efficiency,productivity,and selectivity.
基金supported by the Characterization platform for advanced materials funded by the Korea Research Institute of Standards and Science(KRISS-2021-GP2021-0011)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government MSIT(2021M3D1A20396541).
文摘Two-dimensional(2D)transition metal chalcogenides(TMC)and their heterostructures are appealing as building blocks in a wide range of electronic and optoelectronic devices,particularly futuristic memristive and synaptic devices for brain-inspired neuromorphic computing systems.The distinct properties such as high durability,electrical and optical tunability,clean surface,flexibility,and LEGO-staking capability enable simple fabrication with high integration density,energy-efficient operation,and high scalability.This review provides a thorough examination of high-performance memristors based on 2D TMCs for neuromorphic computing applications,including the promise of 2D TMC materials and heterostructures,as well as the state-of-the-art demonstration of memristive devices.The challenges and future prospects for the development of these emerging materials and devices are also discussed.The purpose of this review is to provide an outlook on the fabrication and characterization of neuromorphic memristors based on 2D TMCs.
基金financially supported by National R&D Program(2018M3D1A1058793,2021M3H4A3A02086430)through NRF(National Research Foundation of Korea)funded by the Ministry of Science and ICTsupported by SAIT,Samsung Electronics Co.,Ltd。
文摘Recently,artificial synapses involving an electrochemical reaction of Li-ion have been attributed to have remarkable synaptic properties.Three-terminal synaptic transistors utilizing Li-ion intercalation exhibits reliable synaptic characteristics by exploiting the advantage of nondistributed weight updates owing to stable ion migrations.However,the three-terminal configurations with large and complex structures impede the crossbar array implementation required for hardware neuromorphic systems.Meanwhile,achieving adequate synaptic performances through effective Li-ion intercalation in vertical two-terminal synaptic devices for array integration remains challenging.Here,two-terminal Au/LixCoO_(2)/Pt artificial synapses are proposed with the potential for practical implementation of hardware neural networks.The Au/LixCoO_(2)/Pt devices demonstrated extraordinary neuromorphic behaviors based on a progressive dearth of Li in LixCoO_(2)films.The intercalation and deintercalation of Li-ion inside the films are precisely controlled over the weight control spike,resulting in improved weight control functionality.Various types of synaptic plasticity were imitated and assessed in terms of key factors such as nonlinearity,symmetricity,and dynamic range.Notably,the LixCoO_(2)-based neuromorphic system outperformed three-terminal synaptic transistors in simulations of convolutional neural networks and multilayer perceptrons due to the high linearity and low programming error.These impressive performances suggest the vertical two-terminal Au/LixCoO_(2)/Pt artificial synapses as promising candidates for hardware neural networks.
基金This study was supported by Korea Hydro&Nuclear Power Co.,Ltd.(No.:2018-Tech-21)the National Research Foundation of Korea(NRF)grant funded by the Korea government MSIT(2019M3E6A1064763).
文摘There have been ever-growing demands to develop advanced electrocatalysts for renewable energy conversion over the past decade.As a promising platform for advanced electrocatalysts,reduced graphene oxide(rGO)has attracted substantial research interests in a variety of electrochemical energy conversion reactions.Its versatile utility is mainly attributed to unique physical and chemical properties,such as high specific surface area,tunable electronic structure,and the feasibility of structural modification and functionalization.Here,a comprehensive discussion is provided upon recent advances in the material preparation,characterization,and the catalytic activity of rGO-based electrocatalysts for various electrochemical energy conversion reactions(water splitting,CO2 reduction reaction,N2 reduction reaction,and O2 reduction reaction).Major advantages of rGO and the related challenges for enhancing their catalytic performance are addressed.
基金funded by research grants from the Ministry of Science and Future Planning,Republic of Korea(NRF2018R1A2A1A05019203NRF-2018R1A5A2024425)the Korean Health Technology R&D Project(No.HI15C2842),Ministry of Health&Welfare,Republic of Korea。
文摘Cancer immunotherapy has been intensively investigated in both preclinical and clinical studies.Whereas chemotherapies use cytotoxic drugs to kill tumor cells,cancer immunotherapy is based on the ability of the immune system to fight cancer.Tumors are intimately associated with the immune system:they can suppress the immune response and/or control immune cells to support tumor growth.Immunotherapy has yielded promising results in clinical practice,but some patients show limited responses.This may reflect the complexities of the relationship between a tumor and the immune system.In an effort to improve the current immunotherapies,researchers have exploited nanomaterials in creating new strategies to cure tumors via modulation of the immune system in tumor tissues.Although extensive studies have examined the use of immune checkpoint-based immunotherapy,rather less work has focused on manipulating the innate immune cells.This review examines the recent approaches and challenges in the use of nanomaterials to modulate innate immune cells.
基金National Research Foundation of Korea,Grant/Award Numbers:2021M3H4A1A03057403,2021R1A6A3A03039988,2021R1A6A3A13046700,2021R1A2B5B03001851。
文摘The development of new heterostructures with high photoactivity is a breakthrough for the limitation of solar-driven water splitting.Here,we first introduce indium oxide(In_(2)O_(3))nanorods(NRs)as a novel electron transport layer for bismuth vanadate(BiVO_(4))with a short charge diffusion length.In_(2)O_(3)NRs reinforce the electron transport and hole blocking of BiVO_(4),surpassing the state-of-the-art photoelectrochemical performances of BiVO_(4)-based photoanodes.Also,a tannin-nickel-iron complex(TANF)is used as an oxygen evolution catalyst to speed up the reaction kinetics.The final TANF/BiVO_(4)/In_(2)O_(3)NR photoanode generates photocurrent densities of 7.1 mAcm^(−2) in sulfite oxidation and 4.2 mA cm^(−2) in water oxidation at 1.23 V versus the reversible hydrogen electrode.Furthermore,the“artificial leaf,”which is a tandem cell with a perovskite/silicon solar cell,shows a solar-to-hydrogen conversion efficiency of 6.2%for unbiased solar water splitting.We reveal significant advances in the photoactivity of TANF/BiVO_(4)/In_(2)O_(3)NRs from the tailored nanostructure and band structure for charge dynamics.
文摘The original version of this article,unfortunately,contained some mistakes and unintentional wrong description of Fig.6 and the caption of Figs.9,10.The correct version of Fig.6 is below.The mentioned figure name for the Fig.6 on the manuscript should be updated.In 2D vdW synaptic devices,the length of the tunneling barrier can be increased or decreased on the trapped or detrapped electrons.Kumar et al.reported memristive and neuromorphic devices composed of vertically grown WS2 layer and ZnO(Fig.6e)[149].The interlayer separation between WS2 and ZnO layers serves as an effective porous medium allowing the ZnO to grow with defects.The interfacial region of ZnO,the very contiguous to WS2 layer.
基金supported by National Research Foundation of Korea (NRF) grant funded by the Korea government Ministry of Science and ICT (MSIT) (2021R1A4A3027878, 2021M3H4A3A02086430)supported by the KRISS (Korea Research Institute of Standards and Science) MPI Lab. program
文摘We present a facile method for producing superhydrophobic nanograss-coated （SNGC） glass surfaces that possess both reduced reflectivity and self-cleaning properties at the air/glass interface. The refractive index of a CaF2 nanograss （NG） layer on a glass substrate, deposited by glancing angle vapor deposition, is 1.04 at 500 nm, which is the second-lowest value ever reported so far. The fluorinated NG layer gives rise to a high water contact angle （〉150°） and very efficient cleaning out of dust with water drops. Using the dual functionalities of the SNGC glass, we demonstrate superhydrophobic and antireflective organic photovoltaic cells with excellent power conversion efficiency.
基金funded by the Korea government(MSIT)(NRF2020M2D8A2070866)Republic of Korea and Korea Initiative for fostering University of Research and Innovation Program of the National Research Foundation(NRF)funded by the Korean government(MSIT)(No.2020M3H1A1077095)+1 种基金T.H.Lee and H.W.Jang acknowledge financial support from the Basic Science Research Program funded by the Ministry of Science,ICT&Future Planning(2021R1A2B5B03001851)the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(2020M2D8A206983011).
文摘Although lithium-air batteries(LABs)are considered the promising alternative of existing lithium–ion batteries owing to their high energy density of 11680 W h kg^(-1),their practical applications are limited by the technical issues,such as unstable solid electrolyte interface and dendrite formation from metal anode and insufficient bifunctional activities and durability from cathode catalyst.In order to resolve these bottlenecks,carbon nanostructures have been investigated owing to their high surface area,excellent electrical conductivity,electrochemical stability,and various modification chemistries.Herein,we comprehensively review a recent progress on the design of carbon nanostructures for their applications into metal hosts,protection layers,and bifunctional electrocatalysts of LABs.The correlation between the crystalline,electronic,porous,and chemical structures and the electrochemical properties of carbon nanomaterials are discussed depending on their classification and characteristics.Various chemical modifications,such as morphological control,hierarchical architecturing,heteroatom incorporation,and the formation of composites,for the improved electrochemical performances of anode and cathode will be also addressed.Furthermore,we deal with the perspectives for the ongoing obstruction and future guidance.
基金supported by the Ministry of Science,ICT&Future Planning(2017R1A2B3009135)the Nano-Material Technology Development Program(2016M3A7B4910)through the National Research Foundation of Korea.
文摘An electronic nose(e-nose)is a device that can detect and recognize odors and flavors using a sensor array.It has received considerable interest in the past decade because it is required in several areas such as health care,environmental monitoring,industrial applications,automobile,food storage,and military.However,there are still obstacles in developing a portable e-nose that can be used for a wide variety of applications.For practical applications of an e-nose,it is necessary to collect a massive amount of data from various sensing materials that can transduce interactions with molecules reliably and analyze them via pattern recognition.In addition,the possibility of miniaturizing the e-nose and operating it with low power consumption should be considered.Moreover,it should work efficiently over a long period of time.To satisfy these requirements,several different chemoresistive material platforms including metal oxides,organics such as polymers and carbonbased materials,and two-dimensional materials were investigated as sensor elements for an e-nose.As an individual material has limited selectivity,there is a continuing effort to improve the selectivity and gas sensing properties through surface decoration and compositional and structural variations.To produce a reliable e-nose,which can be used for practical applications,researches in various fields have to be harmonized.This paper reviews the progress of research on e-noses based on a chemoresistive gas sensor array and discusses the inherent challenges and potential solutions.
