Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au...Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration treatment.The well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 frameworks.This novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution reaction.The electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by Au.Meanwhile,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest value.Consequently,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery performance.The work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts.展开更多
We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating pro...We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating protons to at least 10 PeV.A log-parabola form with the photon indexΓ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10 TeV)is found fitting the gamma-ray energy spectrum of the bubble well.UHE sources,“hot spots”correlated with very massive molecular clouds,and a quasi-spherical amorphousγ-ray emitter with a sharp central brightening are observed in the bubble.In the core of~0.5°,spatially associating with a region containing massive OB association(Cygnus OB2)and a microquasar(Cygnus X-3),as well as previously reported multi-TeV sources,an enhanced concentration of UHEγ-rays is observed with 2 photons at energies above 1 PeV.The general feature of the bubble,the morphology,and the energy spectrum,are reasonably reproduced by the assumption of a particle accelerator in the core,continuously injecting protons into the ambient medium.展开更多
Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure ...Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).展开更多
Liquid crystal(LC)photonic devices have attracted intensive attention in recent decades,due to the merits of tunability,cost-effectiveness,and high efficiency.However,the precise and efficient simulation of large-scal...Liquid crystal(LC)photonic devices have attracted intensive attention in recent decades,due to the merits of tunability,cost-effectiveness,and high efficiency.However,the precise and efficient simulation of large-scale three-dimensional electrically stimulated LC photonic devices remains challenging and resource consuming.Here we report a straightforward nonuniform finite difference method(NFDM)for efficiently simulating largescale LC photonic devices by employing a spatially nonuniform mesh grid.展开更多
高容量的SiO (SO)合金基材料是最有希望的下一代锂离子电池负极之一.使用碳纳米管(CNTs)导电添加剂,虽然可以有效地解决SO较差的循环寿命这一难题,然而除了动力学因素之外,其它潜在的作用机理目前仍不明确.在本工作中,一系列的测试结果...高容量的SiO (SO)合金基材料是最有希望的下一代锂离子电池负极之一.使用碳纳米管(CNTs)导电添加剂,虽然可以有效地解决SO较差的循环寿命这一难题,然而除了动力学因素之外,其它潜在的作用机理目前仍不明确.在本工作中,一系列的测试结果表明CNTs可以使电极在循环后依然维持完整的导电网络,确保均匀的电化学反应.CNTs也使得电极局部的体积膨胀得到了抑制,从而避免了固态电解质界面的不断生长,活性材料从集流体剥离,甚至析锂.得益于CNTs的上述作用, SO-CNTs负极在0.5 C (1 C=1600 mA g^(-1))下可以稳定循环200次,其容量保持率为96.2%. CNTs的作用机理也进一步地在商业化的SO/石墨复合负极(SO650-CNTs, 1 C=650 mA g^(-1))中得到了验证,SO650-CNTs在1 C下循环400次后容量保持率为80.6%.本工作为导电添加剂的作用机理提出了新的见解,并将有助于加速合金类负极的商业化进程.展开更多
The Chezhen depression,located in the south of Bohai Bay Basin,is an oil-producing basin in China. The third and fourth members of the Shahejie Formation(E(s3) and E(s4)) are the main source rock series in the Chezhen...The Chezhen depression,located in the south of Bohai Bay Basin,is an oil-producing basin in China. The third and fourth members of the Shahejie Formation(E(s3) and E(s4)) are the main source rock series in the Chezhen depression. Widespread overpressures occurred in the E(s3) and E(s4) from the depths of approximately 2 000 to 4 600 m,with the maximum pressure coefficient of 1.98 from drillstem tests(DST). Among the sonic,resistivity and density logs,sonic-log is the only reliable pressure indicator and can be used to predict the pore pressure with Eaton's method. All the overpressured mudstones in the source rock series have higher acoustic traveltimes compared with normally pressured mudstones at a given depth. The overpressured mudstones in the E(s3) and E(s4) units are characterized by a normal geothermal gradient,high average density values up to 2.5 g/cm^3,strong present-day hydrocarbon generation capability,abundant mature organic matter and high contents of residual hydrocarbons estimated by the Rock-Eval S1 values and chloroform-soluble bitumen "A" values. All suggest that the dominant mechanism for overpressure in the mudstones of source rock series in the Chezhen depression is hydrocarbon generation. A comparison between the matrix porosity of the normally pressured sandstones and overpressured sandstones,the quantitative evaluation of porosity loss caused by compaction and the conventional thin section inspection demonstrate that the sandstones in the Chezhen depression were normally compacted. The high contents of hydrocarbons in the overpressured reservoirs prove that the overpressure in the sandstones of the source rock series was caused by pressure transmission from the source rocks.展开更多
Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition...Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.展开更多
Graphene doping continues to gather momentum because it enables graphene properties to be tuned,thereby affording new properties to,improve the performance of,and expand the application potential of graphene.Graphene ...Graphene doping continues to gather momentum because it enables graphene properties to be tuned,thereby affording new properties to,improve the performance of,and expand the application potential of graphene.Graphene can be chemically doped using various methods such as surface functionalization,hybrid composites(e.g.,nanoparticle decoration),and substitution doping,wherein C atoms are replaced by foreign ones in the graphene lattice.Theoretical works have predicted that graphene could be substitutionally doped by aluminum(Al)atoms,which could hold promise for exciting applications,including hydrogen storage and evolution,and supercapacitors.Other theoretical predictions suggest that Al substitutionally doped graphene(AIG)could serve as a material for gas sensors and the catalytic decomposition of undesirable materials.However,fabricating Al substitutionally doped graphene has proven challenging until now.Herein,we demonstrate how controlled-flow chemical vapor deposition(CVD)implementing a simple solid precursor can yield high-quality and large-area monolayer AIG,and this synthesis is unequivocally confirmed using various characterization methods including local electron energy-loss spectroscopy(EELS).Detailed high-resolution transmission electron microscopy(HRTEM)shows numerous bonding configurations between the Al atoms and the graphene lattice,some of which are not theoretically predicted.Furthermore,the produced AIG shows a CO_(2) capturability superior to those of other substitutionally doped graphenes.展开更多
Vaporization of water during both gas reservoir development and CO2 geological sequestration in saline formations can cause salt precipitation with rapid loss of formation porosity and permeability.Water vaporization ...Vaporization of water during both gas reservoir development and CO2 geological sequestration in saline formations can cause salt precipitation with rapid loss of formation porosity and permeability.Water vaporization and precipitation of halite around a single well from stage production to CO2 injection are studied to investigate the effect on reservoir properties in a gas reservoir.This paper identifies and quantifies post-flood dry zones and permeability changes in depleted gas reservoir after CO2 exposure with the comparison in gas production period by performing the numerical simulation with the compositional simulator.Simulation results indicate that water vaporization and salt precipitation occur during gas production,and can be intensified by CO2 injection.Dry supercritical CO2 injection vaporizes the brine promoting brine concentration and halite precipitation.The simulation indicates a drying area with a radius of 78 m around wellbore after CO2 injection.Porosity reduces with the most scope of 58%,and permeability can be decreased by up to 93.9%due to salt precipitation.And the injectivity is damaged by 99.77%at the end of injection period based on maximum permeability reduction.Moreover,six factors are investigated to conduct the influence analysis,showing that higher salinity brine,higher injection rate,higher irreducible water saturation,lower initial permeability,higher temperature and with capillary flow are conditions enhancing the salt precipitation due to dry CO2 injection.展开更多
The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based apt...The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.展开更多
Cosmic rays(CRs)are relativistic charged particles in the interstellar medium(ISM).They are mainly protons(hydrogen nuclei)with about 10%fraction of helium nuclei and smaller abundances of heavier elements.CRs are an ...Cosmic rays(CRs)are relativistic charged particles in the interstellar medium(ISM).They are mainly protons(hydrogen nuclei)with about 10%fraction of helium nuclei and smaller abundances of heavier elements.CRs are an important component in ISM.In our galaxy,the energy density of CRs is similar to that of the magnetic fields and interstellar radiation fields(ISRFs).CRs also determine the ionization rate and heating of gas in the dense core of molecular clouds,thus playing a leading role in the astro-chemistry processes therein and controling the star-forming processes.More than a century has passed since Hess discovered the extra-terrestrial origin of CRs(in 1912),yet the origin of CRs still remains as a mystery.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:52102260,52171211,51972220,61903235,U22A20145Shandong Provincial Natural Science Foundation,Grant/Award Numbers:ZR2020QB069,ZR2022ME051+4 种基金National Key Research and Development Program of China,Grant/Award Number:2022YFB4002004Scientific and Technological Innovation Ability Improvement Project of Minor Enterprises in Shandong Province,Grant/Award Number:2022TSGC1021Announce the List and Take Charge Project in Jinan,Grant/Award Number:202214012Major innovation project for integrating science,education and industry of Qilu University of Technology (Shandong Academy of Sciences),Grant/Award Numbers:2022JBZ01-07,2022PY044China Postdoctoral Science Foundation,Grant/Award Number:2022M711545。
文摘Enhancing both the number of active sites available and the intrinsic activity of Co-based electrocatalysts simultaneously is a desirable goal.Herein,a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles(NPs)(denoted as HP-Au@CoxSy@ZIF-67)hybrid is synthesized by low-temperature sulfuration treatment.The well-defined macroporous-mesoporous-microporous structure is obtained based on the combination of polystyrene spheres,as-formed CoxSy nanosheets,and ZIF-67 frameworks.This novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces,accelerating the mass transfer and exposing the active centers for oxygen evolution reaction.The electronic structure of Co is modulated by Au through charge transfer,and a series of experiments,together with theoretical analysis,is performed to ascertain the electronic modulation of Co by Au.Meanwhile,HP-Au@CoxSy@ZIF-67 catalysts with different amounts of Au were synthesized,wherein Au and NaBH4 reductant result in an interesting“competition effect”to regulate the relative ratio of Co^(2+)/Co^(3+),and moderate Au assists the electrochemical performance to reach the highest value.Consequently,the optimized HP-Au@CoxSy@ZIF-67 exhibits a low overpotential of 340 mV at 10 mA cm^(-2)and a Tafel slope of 42 mV dec-1 for OER in 0.1 M aqueous KOH,enabling efficient water splitting and Zn-air battery performance.The work here highlights the pivotal roles of both microstructural and electronic modulation in enhancing electrocatalytic activity and presents a feasible strategy for designing and optimizing advanced electrocatalysts.
基金supported in China by the National Key R&D Program of China(2018YFA0404201,2018YFA0404202,2018YFA0404203,and 2018YFA0404204)the National Natural Science Foundation of China(12105294,12022502,12261160362,12205314,U1931201,and U2031105)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022010)in Thailand by the National Science and Technology Development Agency(NSTDA)and National Research Council of Thailand(NRCT):High-Potential Research Team Grant Program(N42A650868).
文摘We report the detection of aγ-ray bubble spanning at least 100deg2 in ultra-high energy(UHE)up to a few PeV in the direction of the star-forming region Cygnus X,implying the presence super PeVatron(s)accelerating protons to at least 10 PeV.A log-parabola form with the photon indexΓ(E)=(2.71±0.02)+(0.11±0.02)×log10(E/10 TeV)is found fitting the gamma-ray energy spectrum of the bubble well.UHE sources,“hot spots”correlated with very massive molecular clouds,and a quasi-spherical amorphousγ-ray emitter with a sharp central brightening are observed in the bubble.In the core of~0.5°,spatially associating with a region containing massive OB association(Cygnus OB2)and a microquasar(Cygnus X-3),as well as previously reported multi-TeV sources,an enhanced concentration of UHEγ-rays is observed with 2 photons at energies above 1 PeV.The general feature of the bubble,the morphology,and the energy spectrum,are reasonably reproduced by the assumption of a particle accelerator in the core,continuously injecting protons into the ambient medium.
基金supported in part by the National Natural Science Foundation of China(52102218)the National Key Research and Development Program of China(2020YFA0710303)+2 种基金the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ127)the Minjiang Scholar Professorship(GXRC-21004)the Natural Science Foundation of Fujian Province(2021J01594).
文摘Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).
基金National Natural Science Foundation of China(61805087)Science and Technology Program of Guangzhou(2019050001,202102020604,202201010351)+2 种基金Natural Science Foundation of Guangdong Province(2018A030313368)Special Program on Key Fields for Colleges and Universities of Guangdong Province(2021ZDZX1048)Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(2023B1212060065)。
文摘Liquid crystal(LC)photonic devices have attracted intensive attention in recent decades,due to the merits of tunability,cost-effectiveness,and high efficiency.However,the precise and efficient simulation of large-scale three-dimensional electrically stimulated LC photonic devices remains challenging and resource consuming.Here we report a straightforward nonuniform finite difference method(NFDM)for efficiently simulating largescale LC photonic devices by employing a spatially nonuniform mesh grid.
基金supported by the National Natural Science Foundation of China (52071225)the European Regional Development Fund for the “Institute of Environmental Technology-Excellent Research” (CZ.02.1.01/0.0/0.0/16_019/0000853) from Czech Republic+7 种基金the Sino-German Research Institute for their support (Project GZ 1400)the National Natural Science Foundation of China (11874044)the National Natural Science Foundation of China (51702225)Beijing Municipal Science and Technology Commission (Z161100002116020)the Natural Science Foundation of Jiangsu Province (BK20170336)the National Natural Science Foundation of China (51972220 and 51572181)the National Key Research and Development Program of China (2016YFB0100200)the Key University Science Research Project of Jiangsu Province (20KJA480003)。
文摘高容量的SiO (SO)合金基材料是最有希望的下一代锂离子电池负极之一.使用碳纳米管(CNTs)导电添加剂,虽然可以有效地解决SO较差的循环寿命这一难题,然而除了动力学因素之外,其它潜在的作用机理目前仍不明确.在本工作中,一系列的测试结果表明CNTs可以使电极在循环后依然维持完整的导电网络,确保均匀的电化学反应.CNTs也使得电极局部的体积膨胀得到了抑制,从而避免了固态电解质界面的不断生长,活性材料从集流体剥离,甚至析锂.得益于CNTs的上述作用, SO-CNTs负极在0.5 C (1 C=1600 mA g^(-1))下可以稳定循环200次,其容量保持率为96.2%. CNTs的作用机理也进一步地在商业化的SO/石墨复合负极(SO650-CNTs, 1 C=650 mA g^(-1))中得到了验证,SO650-CNTs在1 C下循环400次后容量保持率为80.6%.本工作为导电添加剂的作用机理提出了新的见解,并将有助于加速合金类负极的商业化进程.
基金sponsored by the China National Science and Technology Major Project (No. 2016ZX05006003-001)the Programme of Introducing Talents of Discipline to Universities (No. B14031)+1 种基金the National Natural Science Foundation of China (Nos. 41572114, 41302110)The SINOPEC Shengli Oilfield is thanked for providing background geological data and support
文摘The Chezhen depression,located in the south of Bohai Bay Basin,is an oil-producing basin in China. The third and fourth members of the Shahejie Formation(E(s3) and E(s4)) are the main source rock series in the Chezhen depression. Widespread overpressures occurred in the E(s3) and E(s4) from the depths of approximately 2 000 to 4 600 m,with the maximum pressure coefficient of 1.98 from drillstem tests(DST). Among the sonic,resistivity and density logs,sonic-log is the only reliable pressure indicator and can be used to predict the pore pressure with Eaton's method. All the overpressured mudstones in the source rock series have higher acoustic traveltimes compared with normally pressured mudstones at a given depth. The overpressured mudstones in the E(s3) and E(s4) units are characterized by a normal geothermal gradient,high average density values up to 2.5 g/cm^3,strong present-day hydrocarbon generation capability,abundant mature organic matter and high contents of residual hydrocarbons estimated by the Rock-Eval S1 values and chloroform-soluble bitumen "A" values. All suggest that the dominant mechanism for overpressure in the mudstones of source rock series in the Chezhen depression is hydrocarbon generation. A comparison between the matrix porosity of the normally pressured sandstones and overpressured sandstones,the quantitative evaluation of porosity loss caused by compaction and the conventional thin section inspection demonstrate that the sandstones in the Chezhen depression were normally compacted. The high contents of hydrocarbons in the overpressured reservoirs prove that the overpressure in the sandstones of the source rock series was caused by pressure transmission from the source rocks.
基金supported by the National Natural Science Foundation of China(Nos.21774073,51690151,21404071,and 21320102006)the National Basic Research Program (No. 2016YFA0201500)
文摘Cobalt and nitrogen codoped carbon materials(Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO_2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.
基金supported by the National Natural Science Foundation of China(NSFC,No.52071225)the National Science Center,and the Czech Republic under the ERDF program“Institute of Environmental Technology-Excellent Research”(No.CZ.02.1.01/0.0/0.0/16-019/0000853)M.H.R.and L.F.thank the Sino-German Research Institute for support(No.GZ 1400).
文摘Graphene doping continues to gather momentum because it enables graphene properties to be tuned,thereby affording new properties to,improve the performance of,and expand the application potential of graphene.Graphene can be chemically doped using various methods such as surface functionalization,hybrid composites(e.g.,nanoparticle decoration),and substitution doping,wherein C atoms are replaced by foreign ones in the graphene lattice.Theoretical works have predicted that graphene could be substitutionally doped by aluminum(Al)atoms,which could hold promise for exciting applications,including hydrogen storage and evolution,and supercapacitors.Other theoretical predictions suggest that Al substitutionally doped graphene(AIG)could serve as a material for gas sensors and the catalytic decomposition of undesirable materials.However,fabricating Al substitutionally doped graphene has proven challenging until now.Herein,we demonstrate how controlled-flow chemical vapor deposition(CVD)implementing a simple solid precursor can yield high-quality and large-area monolayer AIG,and this synthesis is unequivocally confirmed using various characterization methods including local electron energy-loss spectroscopy(EELS).Detailed high-resolution transmission electron microscopy(HRTEM)shows numerous bonding configurations between the Al atoms and the graphene lattice,some of which are not theoretically predicted.Furthermore,the produced AIG shows a CO_(2) capturability superior to those of other substitutionally doped graphenes.
基金The authors wish to express their gratitude to the editors and the reviewers for the helpful comments. This research is supported by the National Nature Science Foundation of China (No. 11601070) and Heilongjiang Provincial Natural Science Foundation (No. A2015016).
基金the Project of Innovation Team of Sichuan Education Department No.16TD0010the National Natural Science Foundation of China No.51274173。
文摘Vaporization of water during both gas reservoir development and CO2 geological sequestration in saline formations can cause salt precipitation with rapid loss of formation porosity and permeability.Water vaporization and precipitation of halite around a single well from stage production to CO2 injection are studied to investigate the effect on reservoir properties in a gas reservoir.This paper identifies and quantifies post-flood dry zones and permeability changes in depleted gas reservoir after CO2 exposure with the comparison in gas production period by performing the numerical simulation with the compositional simulator.Simulation results indicate that water vaporization and salt precipitation occur during gas production,and can be intensified by CO2 injection.Dry supercritical CO2 injection vaporizes the brine promoting brine concentration and halite precipitation.The simulation indicates a drying area with a radius of 78 m around wellbore after CO2 injection.Porosity reduces with the most scope of 58%,and permeability can be decreased by up to 93.9%due to salt precipitation.And the injectivity is damaged by 99.77%at the end of injection period based on maximum permeability reduction.Moreover,six factors are investigated to conduct the influence analysis,showing that higher salinity brine,higher injection rate,higher irreducible water saturation,lower initial permeability,higher temperature and with capillary flow are conditions enhancing the salt precipitation due to dry CO2 injection.
基金supported by Guangdong Province Basic and Applied Basic Research Foundation (2021A1515110236)the National Natural Science Foundation of China (62004070)+4 种基金the Science and Technology Program of Guangzhou (2019050001,202201010248)the Youth Innovation Project of Guangdong Education Department(2020KQNCX018)the Young Scholar Foundation of South China Normal University (21KJ08)the “Climbing Program” Special Funds of Guangdong Province (pdjh2022b0133)partially supported by the Science and Technology Planning Project of Guangdong Province (2020B1212060067)
文摘The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.
基金supported by the NSFC under grants 12041305,11421303the natioral youth thousand talents program in China.
文摘Cosmic rays(CRs)are relativistic charged particles in the interstellar medium(ISM).They are mainly protons(hydrogen nuclei)with about 10%fraction of helium nuclei and smaller abundances of heavier elements.CRs are an important component in ISM.In our galaxy,the energy density of CRs is similar to that of the magnetic fields and interstellar radiation fields(ISRFs).CRs also determine the ionization rate and heating of gas in the dense core of molecular clouds,thus playing a leading role in the astro-chemistry processes therein and controling the star-forming processes.More than a century has passed since Hess discovered the extra-terrestrial origin of CRs(in 1912),yet the origin of CRs still remains as a mystery.