Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approache...Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approaches,it remains challenging to achieve a catalytically favorable coordination structure simultaneously with the feasible formation of SACs at low temperatures.Here,a new type of coordination structure for Pt SACs is introduced to offer a highly efficient hydrogen evolution reaction(HER)catalyst,where Pt SACs are readily fabricated by atomically confining PtCl_(2)on chemically driven NO_(2)sites in two-dimensional nitrogen-doped carbon nanosheets at room temperature.The resultant Pt SACs form the NO_(2)-Pt-Cl_(2)coordination structure with an atomic dispersion,as revealed by X-ray spectroscopy and transmission electron microscopy investigations.Moreover,our first-principles density functional theory(DFT)calculations show strong interactions in the coordination by computing the binding energy and charge density difference between PtCl_(2)and NO_(2).Pt SACs,established on the NO_(2)-functionalized carbon support,demonstrate the onset potential of 25 mV,Tafel slope of 40 mV dec^(-1),and high specific activity of 1.35 A mgPt^(-1).Importantly,the Pt SACs also exhibit long-term stability up to 110 h,which is a significant advance in the field of single-atom Pt catalysts.The newly developed coordination structure of Pt SACs features a single Pt active center,providing hydrogen binding ability comparable to that of Pt(111),enhanced long-term durability due to strong metal-support interactions,and the advantage of room-temperature fabrication.展开更多
This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollu...This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollutants.Organic-inorganic composite dots are formed on flexible PI electrodes using evaporation-induced self-assembly(EISA)and electrospray methods.The EISA process is induced by a temperature gradient during electrospray,and the heated substrate partially decomposes the organic parts etched by O_(2) plasma,creating mesoporous structures.Differential pulse voltammetry and cyclic voltammetry demonstrate a linear correlation between analyte concentration and the electrochemical response.Computational studies support the spontaneous adsorption of CC and HQ molecules on model WO_(3) surfaces.The proposed sensor shows high sensitivity,a wide linear range,and a low detection limit for both individual and simultaneous determination of CC and HQ.Real sample analysis on river water confirms practical applicability.The WO_(3)-decorated PI electrode presents an efficient and reliable approach for detecting these pollutants,contributing to environmental safety measures.展开更多
Metal-organic frameworks(MOFs)are a subclass of porous materials that have gained considerable at-tention recently due to their unique properties and potential applications.However,MOFs may exhibit defects affecting t...Metal-organic frameworks(MOFs)are a subclass of porous materials that have gained considerable at-tention recently due to their unique properties and potential applications.However,MOFs may exhibit defects affecting their gas separation performance,limiting their practical applications.This review arti-cle focuses on defects in MOFs and their impact on gas separation.Additionally,the reports explore the potential of De novo and post-synthetic modification(PSM)to improve the gas separation properties by tuning their defects.The PSM of MOFs is discussed in detail,including the different types of modifications and their effects on the MOF properties.Finally,the article discusses the potential of PSM for practical gas separation applications,highlighting recent examples of MOF-based membranes and adsorbents with improved gas separation performance resulting from PSM.It is strategically reasonable to have defects inside the MOFs,but why is it so fascinating in gas separation applications?In this present review,we have tried to uncover the mystery of defects.Overall,this review highlights the importance of defects in MOFs and the potential of PSM strategies to enhance their gas separation properties.展开更多
Atomically dispersed single-atom catalysts(SACs)on carbon supports show great promise for H_(2)O_(2) electrosynthesis,but conventional wet chemistry methods using particulate carbon blacks in powder form have limited ...Atomically dispersed single-atom catalysts(SACs)on carbon supports show great promise for H_(2)O_(2) electrosynthesis,but conventional wet chemistry methods using particulate carbon blacks in powder form have limited their potential as two-electron(2^(e−))oxygen reduction reaction(ORR)catalysts.Here,we demonstrate high-performance Co SACs supported on a free-standing aligned carbon nanofiber(CNF)using electrospinning and arc plasma deposition(APD).Based on the surface oxidation treatment of aligned CNF and precise control of the deposition amount in a dry-based APD process,we successfully form densely populated Co SACs on aligned CNF.Through experimental analyses and density functional theory calculations,we reveal that Co SAC has a Co–N_(2)–O_(2) moiety with one epoxy group,leading to excellent 2^(e−)ORR activity.Furthermore,the aligned CNF significantly improves mass transfer in flow cells compared to randomly oriented CNF,showing an overpotential reduction of 30 mV and a 1.3-fold improvement(84.5%)in Faradaic efficiency,and finally achieves an outstanding production rate of 15.75 mol gcat^(−1) h^(−1) at 300 mA cm^(−2).The high-performance Co SAC supported on well-aligned CNF is also applied in an electro-Fenton process,demonstrating rapid removal of methylene blue and bisphenol F due to its exceptional 2e^(−)ORR activity.展开更多
To accelerate the discovery of materials through computations and experiments,a well-established protocol closely bridging these methods is required.We introduce a high-throughput screening protocol for the discovery ...To accelerate the discovery of materials through computations and experiments,a well-established protocol closely bridging these methods is required.We introduce a high-throughput screening protocol for the discovery of bimetallic catalysts that replace palladium(Pd),where the similarities in the electronic density of states patterns were employed as a screening descriptor.Using first-principles calculations,we screened 4350 bimetallic alloy structures and proposed eight candidates expected to have catalytic performance comparable to that of Pd.Our experiments demonstrate that four bimetallic catalysts indeed exhibit catalytic properties comparable to those of Pd.Moreover,we discover a bimetallic(Ni-Pt)catalyst that has not yet been reported for H_(2)O_(2) direct synthesis.In particular,Ni_(61)Pt_(39) outperforms the prototypical Pd catalyst for the chemical reaction and exhibits a 9.5-fold enhancement in cost-normalized productivity.This protocol provides an opportunity for the catalyst discovery for the replacement or reduction in the use of the platinum-group metals.展开更多
Monodispersed ZnS nano-spheres were synthesized by a simple precipitation. By adjusting the concentration of Zn and S sources, the particle size and morphology were easily controlled. Careful examination of the obtain...Monodispersed ZnS nano-spheres were synthesized by a simple precipitation. By adjusting the concentration of Zn and S sources, the particle size and morphology were easily controlled. Careful examination of the obtained par- ticles suggested porous structures composed of building blocks of small crystallites, ca. 4-- 13.4 nm in diameter. A higher [S]/[Zn]-precursor ratio resulted in a bigger crystallite size but a smaller particle size, and vice versa, for the lower precursor ratio. However, an extreme [S]/[Zn] ratio of 20 provided no spherical aggregation, but a formation of amorphous aggregates. We consider the rate to nucleation and the diffusion-controlled aggregation of crystallites to be important parameters in determining particle sizes and size distributions. Size homogeneity of the obtained ZnS nano-spheres, especially with a [S]/[Zn]-precursor ratio of 5, afforded a photonic crystal array that can poten- tially benefit the photocatalytic activity. When the photocatalytic activities of the ZnS nano-spheres obtained via different conditions were compared, it was found that spherical aggregation and high surface areas have a positive effect on catalytic activity. Although using a [S]/[Zn] ratio of 20 provided the highest surface area, the amorphous aggregation and overly excessive use of S caused a detrimental influence on the catalytic activity.展开更多
Extracellular matrix(ECM)undergoes dynamic inflation that dynamically changes ligand nanospacing but has not been explored.Here we utilize ECM-mimicking photocontrolled supramolecular ligand-tunable Azo^(+)self-assemb...Extracellular matrix(ECM)undergoes dynamic inflation that dynamically changes ligand nanospacing but has not been explored.Here we utilize ECM-mimicking photocontrolled supramolecular ligand-tunable Azo^(+)self-assembly composed of azobenzene derivatives(Azo^(+))stacked via cation-πinteractions and stabilized with RGD ligand-bearing poly(acrylic acid).Near-infrared-upconverted-ultraviolet light induces cis-Azo^(+)-mediated inflation that suppresses cation-πinteractions,thereby inflating liganded self-assembly.This inflation increases nanospacing of“closely nanospaced”ligands from 1.8 nm to 2.6 nm and the surface area of liganded selfassembly that facilitate stem cell adhesion,mechanosensing,and differentiation both in vitro and in vivo,including the release of loaded molecules by destabilizing water bridges and hydrogen bonds between the Azo^(+)molecules and loaded molecules.Conversely,visible light induces trans-Azo^(+)formation that facilitates cation-πinteractions,thereby deflating self-assembly with“closely nanospaced”ligands that inhibits stem cell adhesion,mechanosensing,and differentiation.In stark contrast,when ligand nanospacing increases from 8.7 nm to 12.2 nm via the inflation of self-assembly,the surface area of“distantly nanospaced”ligands increases,thereby suppressing stem cell adhesion,mechanosensing,and differentiation.Long-term in vivo stability of self-assembly via real-time tracking and upconversion are verified.This tuning of ligand nanospacing can unravel dynamic ligand-cell interactions for stem cell-regulated tissue regeneration.展开更多
基金supported by the National Research Foundation of Korea(NRF)(NRF-2020M3H4A3106354,NRF-2021M3I3A1083946,and NRF-2021R1A6A3A01087461)the Korea Institute of Science and Technology,and the KISTI Supercomputing Center(KSC-2023-CRE-0492).
文摘Single-atom catalysts(SACs)have garnered interest in designing their ligand environments,facilitating the modification of single catalytic sites toward high activity and selectivity.Despite various synthetic approaches,it remains challenging to achieve a catalytically favorable coordination structure simultaneously with the feasible formation of SACs at low temperatures.Here,a new type of coordination structure for Pt SACs is introduced to offer a highly efficient hydrogen evolution reaction(HER)catalyst,where Pt SACs are readily fabricated by atomically confining PtCl_(2)on chemically driven NO_(2)sites in two-dimensional nitrogen-doped carbon nanosheets at room temperature.The resultant Pt SACs form the NO_(2)-Pt-Cl_(2)coordination structure with an atomic dispersion,as revealed by X-ray spectroscopy and transmission electron microscopy investigations.Moreover,our first-principles density functional theory(DFT)calculations show strong interactions in the coordination by computing the binding energy and charge density difference between PtCl_(2)and NO_(2).Pt SACs,established on the NO_(2)-functionalized carbon support,demonstrate the onset potential of 25 mV,Tafel slope of 40 mV dec^(-1),and high specific activity of 1.35 A mgPt^(-1).Importantly,the Pt SACs also exhibit long-term stability up to 110 h,which is a significant advance in the field of single-atom Pt catalysts.The newly developed coordination structure of Pt SACs features a single Pt active center,providing hydrogen binding ability comparable to that of Pt(111),enhanced long-term durability due to strong metal-support interactions,and the advantage of room-temperature fabrication.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Education(RS-202300243390 and 2020R1A5A1018052)supported by the Basic Science Research Program through the National Research Foundation of Korea,funded by the Ministry of Education(2022R1A3B1078163)supported by the Technology Innovation Program(Publicprivate joint investment semiconductor R&D program[K-CHIPS])to foster high-quality human resources(RS-2023-00235484)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)(1415187770)。
文摘This study demonstrates the fabrication of mesoporous tungsten trioxide(WO_(3))-decorated flexible polyimide(PI)electrodes for the highly sensitive detection of catechol(CC)and hydroquinone(HQ),two environmental pollutants.Organic-inorganic composite dots are formed on flexible PI electrodes using evaporation-induced self-assembly(EISA)and electrospray methods.The EISA process is induced by a temperature gradient during electrospray,and the heated substrate partially decomposes the organic parts etched by O_(2) plasma,creating mesoporous structures.Differential pulse voltammetry and cyclic voltammetry demonstrate a linear correlation between analyte concentration and the electrochemical response.Computational studies support the spontaneous adsorption of CC and HQ molecules on model WO_(3) surfaces.The proposed sensor shows high sensitivity,a wide linear range,and a low detection limit for both individual and simultaneous determination of CC and HQ.Real sample analysis on river water confirms practical applicability.The WO_(3)-decorated PI electrode presents an efficient and reliable approach for detecting these pollutants,contributing to environmental safety measures.
基金support through the National Research Foundation of Korea(NRF)grant funded by the Ko-rean government(MSIT)(Nos.NRF-2022R1C1C1003313 and NRF-2020M3H4A3106356)supported by the Technology Innovation Program(No.20010846)+2 种基金funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)supported by the“Regional Innovation Strategy(RIS)”through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(MOE)(No.2023RIS-007)support through the Korea Environ-ment Industry&Technology Institute,funded by the Korea Ministry。
文摘Metal-organic frameworks(MOFs)are a subclass of porous materials that have gained considerable at-tention recently due to their unique properties and potential applications.However,MOFs may exhibit defects affecting their gas separation performance,limiting their practical applications.This review arti-cle focuses on defects in MOFs and their impact on gas separation.Additionally,the reports explore the potential of De novo and post-synthetic modification(PSM)to improve the gas separation properties by tuning their defects.The PSM of MOFs is discussed in detail,including the different types of modifications and their effects on the MOF properties.Finally,the article discusses the potential of PSM for practical gas separation applications,highlighting recent examples of MOF-based membranes and adsorbents with improved gas separation performance resulting from PSM.It is strategically reasonable to have defects inside the MOFs,but why is it so fascinating in gas separation applications?In this present review,we have tried to uncover the mystery of defects.Overall,this review highlights the importance of defects in MOFs and the potential of PSM strategies to enhance their gas separation properties.
基金This work was supported by the KIST Institutional Program(2E32461)the NationalResearch Council of Science&Technology(NST)grant(CPS21041-100)+1 种基金the National Research Foundation ofKorea(NRF)grant funded by the Korea Government(MSIT)(No.RS-2023-00209940,NRF-2022R 1F1A1068725, NRF-2022M3H4A7046278)Korea EnvironmentIndustry&Technology Institute(KEITI)through theEcological Imitation-based Environmental Pollution Man-agement Technology Development Project,funded by theKorea Ministry of Environment(MOE)(2021002800005).
文摘Atomically dispersed single-atom catalysts(SACs)on carbon supports show great promise for H_(2)O_(2) electrosynthesis,but conventional wet chemistry methods using particulate carbon blacks in powder form have limited their potential as two-electron(2^(e−))oxygen reduction reaction(ORR)catalysts.Here,we demonstrate high-performance Co SACs supported on a free-standing aligned carbon nanofiber(CNF)using electrospinning and arc plasma deposition(APD).Based on the surface oxidation treatment of aligned CNF and precise control of the deposition amount in a dry-based APD process,we successfully form densely populated Co SACs on aligned CNF.Through experimental analyses and density functional theory calculations,we reveal that Co SAC has a Co–N_(2)–O_(2) moiety with one epoxy group,leading to excellent 2^(e−)ORR activity.Furthermore,the aligned CNF significantly improves mass transfer in flow cells compared to randomly oriented CNF,showing an overpotential reduction of 30 mV and a 1.3-fold improvement(84.5%)in Faradaic efficiency,and finally achieves an outstanding production rate of 15.75 mol gcat^(−1) h^(−1) at 300 mA cm^(−2).The high-performance Co SAC supported on well-aligned CNF is also applied in an electro-Fenton process,demonstrating rapid removal of methylene blue and bisphenol F due to its exceptional 2e^(−)ORR activity.
基金This work was supported by Creative Materials Discovery Program through the National Research Foundation of Korea(NRF-2016M3D1A1021141)We acknowledge the financial supports of the Korea Institute of Science and Technology(Grant no.2E30460).
文摘To accelerate the discovery of materials through computations and experiments,a well-established protocol closely bridging these methods is required.We introduce a high-throughput screening protocol for the discovery of bimetallic catalysts that replace palladium(Pd),where the similarities in the electronic density of states patterns were employed as a screening descriptor.Using first-principles calculations,we screened 4350 bimetallic alloy structures and proposed eight candidates expected to have catalytic performance comparable to that of Pd.Our experiments demonstrate that four bimetallic catalysts indeed exhibit catalytic properties comparable to those of Pd.Moreover,we discover a bimetallic(Ni-Pt)catalyst that has not yet been reported for H_(2)O_(2) direct synthesis.In particular,Ni_(61)Pt_(39) outperforms the prototypical Pd catalyst for the chemical reaction and exhibits a 9.5-fold enhancement in cost-normalized productivity.This protocol provides an opportunity for the catalyst discovery for the replacement or reduction in the use of the platinum-group metals.
文摘Monodispersed ZnS nano-spheres were synthesized by a simple precipitation. By adjusting the concentration of Zn and S sources, the particle size and morphology were easily controlled. Careful examination of the obtained par- ticles suggested porous structures composed of building blocks of small crystallites, ca. 4-- 13.4 nm in diameter. A higher [S]/[Zn]-precursor ratio resulted in a bigger crystallite size but a smaller particle size, and vice versa, for the lower precursor ratio. However, an extreme [S]/[Zn] ratio of 20 provided no spherical aggregation, but a formation of amorphous aggregates. We consider the rate to nucleation and the diffusion-controlled aggregation of crystallites to be important parameters in determining particle sizes and size distributions. Size homogeneity of the obtained ZnS nano-spheres, especially with a [S]/[Zn]-precursor ratio of 5, afforded a photonic crystal array that can poten- tially benefit the photocatalytic activity. When the photocatalytic activities of the ZnS nano-spheres obtained via different conditions were compared, it was found that spherical aggregation and high surface areas have a positive effect on catalytic activity. Although using a [S]/[Zn] ratio of 20 provided the highest surface area, the amorphous aggregation and overly excessive use of S caused a detrimental influence on the catalytic activity.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.RS-2023-00208427,2021R1I1A1A01046207,2021R1A2C2005418,2022R1A2C2005943,and 2022M3H4A1A03076638)supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.RS-2023-00271399 and RS-2023-00275654)+1 种基金supported by a Korea University Grant and KIST intramural programHAADF-STEM was conducted with the support of the Seoul center in Korea Basic Science Institute(KBSI).
文摘Extracellular matrix(ECM)undergoes dynamic inflation that dynamically changes ligand nanospacing but has not been explored.Here we utilize ECM-mimicking photocontrolled supramolecular ligand-tunable Azo^(+)self-assembly composed of azobenzene derivatives(Azo^(+))stacked via cation-πinteractions and stabilized with RGD ligand-bearing poly(acrylic acid).Near-infrared-upconverted-ultraviolet light induces cis-Azo^(+)-mediated inflation that suppresses cation-πinteractions,thereby inflating liganded self-assembly.This inflation increases nanospacing of“closely nanospaced”ligands from 1.8 nm to 2.6 nm and the surface area of liganded selfassembly that facilitate stem cell adhesion,mechanosensing,and differentiation both in vitro and in vivo,including the release of loaded molecules by destabilizing water bridges and hydrogen bonds between the Azo^(+)molecules and loaded molecules.Conversely,visible light induces trans-Azo^(+)formation that facilitates cation-πinteractions,thereby deflating self-assembly with“closely nanospaced”ligands that inhibits stem cell adhesion,mechanosensing,and differentiation.In stark contrast,when ligand nanospacing increases from 8.7 nm to 12.2 nm via the inflation of self-assembly,the surface area of“distantly nanospaced”ligands increases,thereby suppressing stem cell adhesion,mechanosensing,and differentiation.Long-term in vivo stability of self-assembly via real-time tracking and upconversion are verified.This tuning of ligand nanospacing can unravel dynamic ligand-cell interactions for stem cell-regulated tissue regeneration.
