Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermionspin theory. It is shown that the temperature-dependent thermal conductivity is characterized by the low-temperature...Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermionspin theory. It is shown that the temperature-dependent thermal conductivity is characterized by the low-temperature peak located at a finite temperature. The thermal conductivity increases monotonously with increasing temperature at low-temperatures T 〈 0.1 J, and then decreases with increasing temperature for higher temperatures T 〉 0.1 J, in qualitative agreement with experimental result observed from NaxCoO2.展开更多
The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review present...The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review presents an overview of the research progress on oxidation behavior of Co-based superalloys, including oxidation kinetics, oxides morphology, the formation and spallation of oxide layers, and importantly, the synergistic effects of alloying elements on oxidation resistance—a critical area considering the complex interactions with multiple alloying elements. Additionally, this review compares the oxidation resistance of single crystal versus polycrystalline alloys. The effect of phase interface and dislocations on oxidation behavior is also discussed. While significant progress has been achieved, areas necessitating further investigation include optimizing alloy compositions for enhanced oxidation resistance and understanding the long-term stability of oxide layers. The future prospects for Co-based superalloys are promising as ongoing research aims to address the existing challenges and unlock new applications at even higher operating temperatures.展开更多
Seawater electrolysis is a promising approach for sustainable energy without relying on precious freshwater.However,the large-scale seawater electrolysis is hindered by low catalytic efficiency and severe anode corros...Seawater electrolysis is a promising approach for sustainable energy without relying on precious freshwater.However,the large-scale seawater electrolysis is hindered by low catalytic efficiency and severe anode corrosion caused by the harmful chlorine.In contrast to the oxygen evolution reaction (OER)and chlorin ion oxidation reaction (ClOR),glycerol oxidation reaction (GOR) is more thermodynamically and kinetically favorable alternative.Herein,a Ru doping cobalt phosphide (Ru-CoP_(2)) is proposed as a robust bifunctional electrocatalyst for seawater electrolysis and GOR,for the concurrent productions of hydrogen and value-added formate.The in situ and ex situ characterization analyses demonstrated that Ru doping featured in the dynamic reconstruction process from Ru-CoP_(2)to Ru-CoOOH,accounting for the superior GOR performance.Further coupling GOR with hydrogen evolution was realized by employing Ru-CoP_(2)as both anode and cathode,requiring only a low voltage of 1.43 V at 100 mA cm^(-2),which was 250 m V lower than that in alkaline seawater.This work guides the design of bifunctional electrocatalysts for energy-efficient seawater electrolysis coupled with biomass resource upcycling.展开更多
The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation...The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation energy storage systems.However,severe electrode volume changes and sluggish redox kinetics are the critical problems for lithium/potassium ion batteries(LIBs/PIBs)towards large-scale applications.Herein,we prepare a novel anode material,which consists of reduced graphene oxide wrapping one-dimensional(1D)N-doped porous carbon nanotube with cobalt phosphoselenide(CoPSe)nanoparticles embedded inside them(r GO@Co PSe/NC).Benefited from the dual carbon decorations and ultrafine nanoparticles structure,it achieves a reversible capacity of 245 mAh/g at 5 A/g after 2000 cycles for LIBs and 215 mAh/g at 1 A/g after 500 cycles for PIBs.The pseudocapacitance and GITT measurements are used to investigate the electrochemical kinetics of r GO@Co PSe/NC for LIBs.In addition,the lithium ion full cell also shows good electrochemical performance when paired with high capacity LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode.This work provides a feasible electrode design strategy for high-efficiency metal ion batteries based on multidimensional nanoarchitecture engineering and composition tailoring.展开更多
In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.How...In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.However,they are also confronted with the problem of unstable battery performance due to the heavy volume expansion and sluggish ion reaction kinetics.Herein,yolk-shell cobalt phosphosulfide nanocrystals encapsulating into multi-heterogeneous atom(N,P,S)-doped carbon framework(Co_(9)S_(8)/CoP@NPSC)were constructed by employing dodecahedral ZIF-67 as precursor and a polymer as carbon sources through simultaneous sulfidation and phosphorization processes.The synergistic effect of Co_(9)S_(8)and CoP component and the yolk-shell structure greatly improve the bettery performance and structural stability.In addition,the multiple hetero-atoms doped carbon frameworks enhance the conductivity of the electrode materials and increase the spacing of carbon layers to supply sufficient active sites and facilitate the Na^(+)/K^(+)transport.The electrochemical results demonstrated that Co_(9)S_(8)/CoP@NPSC exhibited the pleasant reversible capacity(360.47 mAh/g at 1 A/g)after 300 cycles and an unpredictable cycling stability(103.22 mAh/g after 1000 cycles)in the SIBs application.The ex-situ XRD and XPS analyses were further applied to study the sodium ion storage mechanism and the multi-step phase transition reaction of the yolk-shell heterogeneous structure.This work provides new perspectives for the preparation of novel structure metal phosphosulfide and their applications in anode materials for sodium/potassium batteries and other secondary batteries.展开更多
Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In t...Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In this study,a flake-like nickel cobaltate/re-duced graphene oxide/melamine-derived carbon foam(FNC/RGO/MDCF)was successfully fabricated through a combination of solvo-thermal treatment and high-temperature pyrolysis.Results indicated that RGO was evenly distributed in the MDCF skeleton,providing ef-fective support for the load growth of FNC on its surface.Sample S3,the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h,exhibited a minimum reflection loss(RL_(min))of-66.44 dB at a thickness of 2.29 mm.When the thickness was reduced to 1.50 mm,the optimal effective absorption bandwidth was 3.84 GHz.Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss,multiple reflection,scattering,in-terface polarization,and dipole polarization.展开更多
This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that ...This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.展开更多
The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based ca...The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based cathode La_(0.6)Sr_(0.4)CoO_(3)(LSC)offers excellent catalytic performance,its TEC is significantly larger than that of the electrolyte.In this study,we mechanically mix Sm_(0.2)Ce_(0.8)O_(2−δ)(SDC)with LSC to create a composite cathode.By incorporating 50wt%SDC,the TEC decreases significantly from 18.29×10^(−6) to 13.90×10^(−6) K^(−1).Under thermal-shock conditions ranging from room temperature to 800℃,the growth rate of polarization resistance is only 0.658%per cycle,i.e.,merely 49%that of pure LSC.The button cell comprising the LSC-SDC composite cathode operates stably for over 900 h without Sr segregation,with a voltage growth rate of 1.11%/kh.A commercial flat-tube cell(active area:70 cm^(2))compris-ing the LSC-SDC composite cathode delivers 54.8 W at 750℃.The distribution of relaxation-time shows that the non-electrode portion is the main rate-limiting step.This study demonstrates that the LSC-SDC mixture strategy effectively improves the compatibility with the electrolyte while maintaining a high output,thus rendering it a promising commercial cathode material.展开更多
Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic pollutants.Herei...Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic pollutants.Herein,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom layer.Crucially,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis process.Moreover,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of NaCl.Furthermore,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation efficiency.This work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.展开更多
In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 m...In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 mg·L^(-1),the cobalt coating transformed from disordered large grains to a honeycomb structure,with a preferred orientation of(002)facet on hexago-nal close-packed(HCP)cobalt crystals.The resistivity of the cobalt film decreased to 14.4μΩ·cm,and further decreased to 10.7μΩ·cm after the annealing treatment.When the concentration of saccharin was increased,the grain size was gradually refined and a“stone forest”structure was observed,with the preferred orientation remaining unchanged.The addition of saccharin also slightly improves the purity of cobalt coating to a certain extent.Through the study of the crystallization behavior of cobalt electroless plating,saccharin molecules can adsorb to specific c-sites on the cobalt dense crystal plane,inhibiting the growth of abc stacking arrangement and inducing the crystal growth in ab stacking mode,thereby achieving optimal growth of HCP(002)texture.展开更多
A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal st...A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal structure was characterized.In a three-electrode system,Co-BD,as the electrode material for supercapacitors,achieved a specific capacitance of 830 F·g^(-1)at 1 A·g^(-1),equivalent to a specific capacity of 116.4 mAh·g^(-1),and exhibited high-rate capability,reaching 212 F·g^(-1)at 20 A·g^(-1).Impressively,Co-BD||rGO(reduced graphene oxide),representing an asymmetrical supercapacitor,owns a higher energy density of 14.2 Wh·kg^(-1)at 0.80 kW·kg^(-1),and an excellent cycle performance(After 4000 cycles at 1 A·g^(-1),the capacitance retention was up to 94%).CCDC:2418872.展开更多
Cobalt oxide,as one of the most fascinating examples of correlated electronic system,exhibits several exotic transport characteristics,such as superconductivity,charge ordering,and topological frustration.In this stud...Cobalt oxide,as one of the most fascinating examples of correlated electronic system,exhibits several exotic transport characteristics,such as superconductivity,charge ordering,and topological frustration.In this study,we are reporting the observation of another intriguing transport phenomenon in calcium cobaltates.Specifically,under a large magnetic field of 7 T,we observed an anomalously enhanced thermal conductivity that was accompanied with a largely suppressed thermopower.This observation reveals a hitherto undiscovered correlation between the two transport factors.Within the premise of Heisenberg model,we have shown that the observed experimental results can be explained consistently only if the magnon excitation is taken into account.Our study offers an insight into the puzzling origin of large thermopower observed in layered cobaltates and provides a specific strategy for further optimization of thermopower.展开更多
Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized sin...Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized since 1960s.Heterogeneous catalysis is considered superior owing to the facile separation of catalysts from products,shorter technical process,and reduced manufacturing costs.Unexpectedly,there has not been a single case of plant using heterogenized Co-based catalyst successfully.To address the separation issue and understand the catalytic mechanism of the reactions,this review summarizes the progress in heterogeneous systems and provides a detailed discussion of their catalytic performance.Strategies for stabilizing Co species through support modification and additive incorporation are carefully considered to elucidate why heterogeneous systems have not yet succeeded on an industrial scale.Furthermore,we provide our insights for the development of heterogeneous catalytic hydroformylation,including the challenges,opportunities,and outlooks.The aim is to deepen the fundamental understanding of heterogeneous alkene hydroformylation,guiding the community's research efforts towards realizing its successful application in the future.展开更多
In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.The...In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.展开更多
pH-dependent multiple equilibria in cobalt sulfate-gluconate baths were calculated using stability constants adopted from literature.Changes of the bath speciation were then discussed in terms of spectrophotometric ex...pH-dependent multiple equilibria in cobalt sulfate-gluconate baths were calculated using stability constants adopted from literature.Changes of the bath speciation were then discussed in terms of spectrophotometric experiments and buffering properties of the solutions(pH 3-10).Cyclic voltammetry indicated changes in electrochemical behavior of cobalt species caused by different ionic compositions of the electrolytes.Tafel slopes were calculated and discussed in relation to electroreduction of cobalt species.Chronoamperometric studies showed 3D instantaneous nucleation of cobalt followed by diffusion-controlled growth,but it was disturbed at higher pH due to the release of cation from gluconate complexes as a limiting step.Diffusion coefficients of cobalt species were found.Changes in the pH were also reflected by modifications of morphology(SEM),development of preferred orientation planes(XRD,texture coefficients)and current efficiency,but not the thickness of the coatings deposited at constant potential of-1.0 V(vs Ag/AgCl).Anodic stripping analysis showed changes in anodic responses originated from the existence of preferentially oriented planes in cobalt layers.展开更多
Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-...Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-based catalysts,their further developments are hindered by the uncertainties related to the kind of the active sites involved in the desired and side reactions.To contribute to closing such a gap,we systematically investigate the role of oxidized CoO_(x) and metallic Co0 species in the PDH reaction over catalysts based in Silicalite-1 with supported CoO_(x) species differing in their redox properties.C_(3)H_(8) pulse experiments with sub-millisecond and second resolution at pulse sizes of about 13 and 2200 nmol,respectively,combined with in-depth catalyst characterization and PDH tests at different propane conversions enabled us to understand how the reaction-induced reduction of CoO_(x) affects product selectivity.Propane readily reacts with CoO_(x) to yield propene,carbon oxides and water.The formed Co0 species show high activity to coking and cracking reactions.However,if the size of such species is below 2 nm,these undesired reactions are significantly hindered due to the coverage of the active sites by carbon-containing species.The remaining uncovered surface Co0 sites selectively dehydrogenate propane to propene.The best-performing catalyst showed higher activity than a commercial-like K-CrOx/Al_(2)O_(3) and operated durable in a series of 10 dehydrogenation/regeneration cycles under industrial relevant conditions.The space time yield of propene formation of 0.97 kg·h^(-1)·kgcat^(-1) was achieved at 550℃,52%equilibrium propane conversion and 95% propene selectivity.展开更多
The asymmetric addition of aromatic organometallic compounds to the carbonyl group(C-3)of isatins,catalyzed by transition metals,has emerged as a remarkably efficient method for the synthesis of chiral 3-hydroxyoxindo...The asymmetric addition of aromatic organometallic compounds to the carbonyl group(C-3)of isatins,catalyzed by transition metals,has emerged as a remarkably efficient method for the synthesis of chiral 3-hydroxyoxindoles.Here,an exceptionally enantioselective approach was developed for the first time to achieve a catalytic NHK reaction of isatins with aromatic halides(both aryl and heteroaryl).Utilizing chiral cobalt complexes as catalysts,and the presence of a diboron reagent B_(2)nep_(2)as both a reducing agent and determinant in enantiocontrol,has resulted in the triumphantly achieved synthesis of enantioenriched products.Compared to reported strategies,this approach exhibits remarkable compatibility with substrates bearing sensitive functional groups,such as halides and borate esters,while also eliminating the need for organometallic reagents as required in previous strategies.Through experimental investigations,the presence of aryl-cobalt species during the addition process was confirmed,rather than in-situ generation of an arylboron reagent.Furthermore,the successful attainment of the R absolute configuration through aryl addition was demonstrated.展开更多
Transition metal-catalyzed functionalization of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity of migratory insertion of alkynes into the C–metal bonds. M...Transition metal-catalyzed functionalization of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity of migratory insertion of alkynes into the C–metal bonds. Moreover, the synthesis of C–N atropisomers has received significantly less attention compared to that of C–C atropisomers and there have been only a few isolated examples reported for the construction of chiral diaxes through C–H functionalization. Herein, we report that cobalt can catalyze the C–H annulations of aminoquinoline amides with directing group-tethered internal alkynes or 1-indolylalkynes for the synthesis of chiral diaxes. A variety of vicinal C–N and C–C chiral diaxes and distal double C–N chiral diaxes were synthesized with excellent regio, diastereo, and enantioselectivity under mild reaction conditions. The ready availability of aminoquinoline amides, alkynes, and Salox ligands and the simplicity and good functional group tolerance of this protocol make it highly attractive.展开更多
The origin of the misorientations after fcc(face-centered cubic)to hcp(hexagonal close-packed)transformation in pure cobalt was elucidated by utilizing the electron backscatter diffraction(EBSD)technique and transform...The origin of the misorientations after fcc(face-centered cubic)to hcp(hexagonal close-packed)transformation in pure cobalt was elucidated by utilizing the electron backscatter diffraction(EBSD)technique and transformation crystallographic models.It is found the Shoji−Nishiyama orientation relationship during fcc→hcp transformation leads to four hcp variants,characterized by a common misorientation angle of 70.5°with respect to the<1120>direction,which is the predominant misorientation observed.Other statistically significant misorientation angles between hcp grains,including 32°,36°,38°,60°,71°and 86°−91°,are also identified.These newly observed misorientation angles are linked to the microstructure of the fcc matrix at elevated temperatures,with twin structures in the fcc matrix being the primary cause.Furthermore,a novel method is proposed for estimating the fraction of twins in the fcc grains based on misorientation angles between hcp variants,which is found to be consistent with experimental observations.In-situ EBSD observations validate the possible origin of fcc twins from the hcp→fcc transformation.展开更多
Understanding the catalytic mechanism at real catalytically active layer is essential for the advancement of water oxidation.Nevertheless,it is difficult to explore the surface effect of active layer of catalysts on o...Understanding the catalytic mechanism at real catalytically active layer is essential for the advancement of water oxidation.Nevertheless,it is difficult to explore the surface effect of active layer of catalysts on oxygen evolution reaction(OER)independently because of the coexistence of bulk phase and surfaceactive layer.Herein,by designing ultra-thin shell amorphous CoO_(x)hollow nanospheres,we explored the effect of single catalytic active layer on OER activity,further revealing the surface catalytic mechanism for seawater oxidation.The amorphous catalytic active layer CoO_(x)contain phosphates(CoO_(x)PO_(4)),induced by completely bulk reconstruction of CoP_(x)hollow nanospheres.Compared with autologous crystalline CoO,amorphous catalytic active species CoO_(x)-PO_(4)possesses higher OER performance with ultralow overpotential of 229 mV to achieve 10 mA cm^(-2).Remarkably,self-built phosphate film could effectively block chloride anions and implement robust seawater oxidation.This work brings direct insights of the surface effect of amorphous catalytic active layer on water oxidation,which is critical for the performance optimization of water oxidation.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10404001 and 90403005
文摘Within the t-J model, the heat transport of electron-doped cobaltates is studied based on the fermionspin theory. It is shown that the temperature-dependent thermal conductivity is characterized by the low-temperature peak located at a finite temperature. The thermal conductivity increases monotonously with increasing temperature at low-temperatures T 〈 0.1 J, and then decreases with increasing temperature for higher temperatures T 〉 0.1 J, in qualitative agreement with experimental result observed from NaxCoO2.
基金support from the National Natural Science Foundation of China(Nos.52171107,52201203)the Hebei Provincial Natural Science Foundation,China(No.E2021501026)the National Natural Science Foundation of China-Joint Fund of Iron and Steel Research(No.U1960204).
文摘The novel Co-based superalloys are extensively used in gas-powered and jet engine turbines due to their excellent high-temperature performance, achieved by strengthening the L12-γ′ ordered phase. This review presents an overview of the research progress on oxidation behavior of Co-based superalloys, including oxidation kinetics, oxides morphology, the formation and spallation of oxide layers, and importantly, the synergistic effects of alloying elements on oxidation resistance—a critical area considering the complex interactions with multiple alloying elements. Additionally, this review compares the oxidation resistance of single crystal versus polycrystalline alloys. The effect of phase interface and dislocations on oxidation behavior is also discussed. While significant progress has been achieved, areas necessitating further investigation include optimizing alloy compositions for enhanced oxidation resistance and understanding the long-term stability of oxide layers. The future prospects for Co-based superalloys are promising as ongoing research aims to address the existing challenges and unlock new applications at even higher operating temperatures.
基金National Natural Science Foundation of China (Nos. 42276035, 22309030)Guangdong Basic and Applied Basic Research Foundation (Nos. 2023A1515012589,2020A1515110473)Key Plat Form Programs and Technology Innovation Team Project of Guangdong Provincial Department of Education (Nos. 2019GCZX002, 2020KCXTD011)。
文摘Seawater electrolysis is a promising approach for sustainable energy without relying on precious freshwater.However,the large-scale seawater electrolysis is hindered by low catalytic efficiency and severe anode corrosion caused by the harmful chlorine.In contrast to the oxygen evolution reaction (OER)and chlorin ion oxidation reaction (ClOR),glycerol oxidation reaction (GOR) is more thermodynamically and kinetically favorable alternative.Herein,a Ru doping cobalt phosphide (Ru-CoP_(2)) is proposed as a robust bifunctional electrocatalyst for seawater electrolysis and GOR,for the concurrent productions of hydrogen and value-added formate.The in situ and ex situ characterization analyses demonstrated that Ru doping featured in the dynamic reconstruction process from Ru-CoP_(2)to Ru-CoOOH,accounting for the superior GOR performance.Further coupling GOR with hydrogen evolution was realized by employing Ru-CoP_(2)as both anode and cathode,requiring only a low voltage of 1.43 V at 100 mA cm^(-2),which was 250 m V lower than that in alkaline seawater.This work guides the design of bifunctional electrocatalysts for energy-efficient seawater electrolysis coupled with biomass resource upcycling.
基金financially supported by the National Natural Science Foundation of China(No.22204028)Young Talent Support Project of Guangzhou Association for Science and Technology(No.QT-2023-003)+3 种基金Guangdong Basic and Applied Basic Research Fund Project(No.2022A1515110451)Guangzhou University Graduate Student Innovation Ability Cultivation Funding Program(No.2022GDJC-M06)Science and Technology Projects in Guangzhou(Nos.202201010245,2023A03J0029)Double-Thousand Talents Plan of Jiangxi Province(No.jxsq2023102005)。
文摘The metal ion batteries have gained widespread attention for wearable electronics due to their competitive energy density and long cycling life.Exploring the advanced anode materials is significant for next generation energy storage systems.However,severe electrode volume changes and sluggish redox kinetics are the critical problems for lithium/potassium ion batteries(LIBs/PIBs)towards large-scale applications.Herein,we prepare a novel anode material,which consists of reduced graphene oxide wrapping one-dimensional(1D)N-doped porous carbon nanotube with cobalt phosphoselenide(CoPSe)nanoparticles embedded inside them(r GO@Co PSe/NC).Benefited from the dual carbon decorations and ultrafine nanoparticles structure,it achieves a reversible capacity of 245 mAh/g at 5 A/g after 2000 cycles for LIBs and 215 mAh/g at 1 A/g after 500 cycles for PIBs.The pseudocapacitance and GITT measurements are used to investigate the electrochemical kinetics of r GO@Co PSe/NC for LIBs.In addition,the lithium ion full cell also shows good electrochemical performance when paired with high capacity LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode.This work provides a feasible electrode design strategy for high-efficiency metal ion batteries based on multidimensional nanoarchitecture engineering and composition tailoring.
基金supported by National Natural Science Foundation of China(Nos.52472194,52101243)Natural Science Foundation of Guangdong Province,China(No.2023A1515012619)the Science and Technology Planning Project of Guangzhou(No.202201010565)。
文摘In recent years,metal phosphosulfides have attracted great attention as the promising anode materials in sodium/potassium batteries because of their incorporation of the advantages of metal phosphides and sulfides.However,they are also confronted with the problem of unstable battery performance due to the heavy volume expansion and sluggish ion reaction kinetics.Herein,yolk-shell cobalt phosphosulfide nanocrystals encapsulating into multi-heterogeneous atom(N,P,S)-doped carbon framework(Co_(9)S_(8)/CoP@NPSC)were constructed by employing dodecahedral ZIF-67 as precursor and a polymer as carbon sources through simultaneous sulfidation and phosphorization processes.The synergistic effect of Co_(9)S_(8)and CoP component and the yolk-shell structure greatly improve the bettery performance and structural stability.In addition,the multiple hetero-atoms doped carbon frameworks enhance the conductivity of the electrode materials and increase the spacing of carbon layers to supply sufficient active sites and facilitate the Na^(+)/K^(+)transport.The electrochemical results demonstrated that Co_(9)S_(8)/CoP@NPSC exhibited the pleasant reversible capacity(360.47 mAh/g at 1 A/g)after 300 cycles and an unpredictable cycling stability(103.22 mAh/g after 1000 cycles)in the SIBs application.The ex-situ XRD and XPS analyses were further applied to study the sodium ion storage mechanism and the multi-step phase transition reaction of the yolk-shell heterogeneous structure.This work provides new perspectives for the preparation of novel structure metal phosphosulfide and their applications in anode materials for sodium/potassium batteries and other secondary batteries.
基金support of the Key Science Research Project in Colleges and Universities of Anhui Province,China(No.2022AH050813)the Medical Special Cultivation Project of Anhui University of Science and Technology,China(No.YZ2023H2A002).
文摘Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and control-lable preparation of metal oxide/carbon-based composite microwave absorption materials.In this study,a flake-like nickel cobaltate/re-duced graphene oxide/melamine-derived carbon foam(FNC/RGO/MDCF)was successfully fabricated through a combination of solvo-thermal treatment and high-temperature pyrolysis.Results indicated that RGO was evenly distributed in the MDCF skeleton,providing ef-fective support for the load growth of FNC on its surface.Sample S3,the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h,exhibited a minimum reflection loss(RL_(min))of-66.44 dB at a thickness of 2.29 mm.When the thickness was reduced to 1.50 mm,the optimal effective absorption bandwidth was 3.84 GHz.Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss,multiple reflection,scattering,in-terface polarization,and dipole polarization.
基金supported by the National Natural Science Foundation of China(No.52271089)the financial support from the C hina Postdoctoral Science Foundation(No.2023M732192)。
文摘This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.
基金the financial support from the National Natural Science Foundation of China(No.22209191)Ningbo Key R&D Project(No.2023Z155).
文摘The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based cathode La_(0.6)Sr_(0.4)CoO_(3)(LSC)offers excellent catalytic performance,its TEC is significantly larger than that of the electrolyte.In this study,we mechanically mix Sm_(0.2)Ce_(0.8)O_(2−δ)(SDC)with LSC to create a composite cathode.By incorporating 50wt%SDC,the TEC decreases significantly from 18.29×10^(−6) to 13.90×10^(−6) K^(−1).Under thermal-shock conditions ranging from room temperature to 800℃,the growth rate of polarization resistance is only 0.658%per cycle,i.e.,merely 49%that of pure LSC.The button cell comprising the LSC-SDC composite cathode operates stably for over 900 h without Sr segregation,with a voltage growth rate of 1.11%/kh.A commercial flat-tube cell(active area:70 cm^(2))compris-ing the LSC-SDC composite cathode delivers 54.8 W at 750℃.The distribution of relaxation-time shows that the non-electrode portion is the main rate-limiting step.This study demonstrates that the LSC-SDC mixture strategy effectively improves the compatibility with the electrolyte while maintaining a high output,thus rendering it a promising commercial cathode material.
基金Financial support from the National Natural Science Foundation of China(51972016)the Fundamental Research Funds for the Central Universities(JD2417)is gratefully acknowledged.
文摘Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic pollutants.Herein,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom layer.Crucially,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis process.Moreover,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of NaCl.Furthermore,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation efficiency.This work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.
基金supported by National Natural Science Foundation of China(22402115,22472094)Shaanxi Special Fund for Talent Introduction(100090/1204071055).
文摘In the process of electroless cobalt plating,the saccharin additive can significantly change the surface morphology,texture orientation,and conductivity of the cobalt coating layer.When the amount of saccharin was 3 mg·L^(-1),the cobalt coating transformed from disordered large grains to a honeycomb structure,with a preferred orientation of(002)facet on hexago-nal close-packed(HCP)cobalt crystals.The resistivity of the cobalt film decreased to 14.4μΩ·cm,and further decreased to 10.7μΩ·cm after the annealing treatment.When the concentration of saccharin was increased,the grain size was gradually refined and a“stone forest”structure was observed,with the preferred orientation remaining unchanged.The addition of saccharin also slightly improves the purity of cobalt coating to a certain extent.Through the study of the crystallization behavior of cobalt electroless plating,saccharin molecules can adsorb to specific c-sites on the cobalt dense crystal plane,inhibiting the growth of abc stacking arrangement and inducing the crystal growth in ab stacking mode,thereby achieving optimal growth of HCP(002)texture.
文摘A low-cost 1D cobalt-based coordination polymer(CP)[Co(BGPD)(DMSO)_(2)(H_(2)O)_(2)](Co-BD;H2BGPD=N,N'-bis(glycinyl)pyromellitic diimide;DMSO=dimethyl sulfoxide)was synthesized by a simple method,and its crystal structure was characterized.In a three-electrode system,Co-BD,as the electrode material for supercapacitors,achieved a specific capacitance of 830 F·g^(-1)at 1 A·g^(-1),equivalent to a specific capacity of 116.4 mAh·g^(-1),and exhibited high-rate capability,reaching 212 F·g^(-1)at 20 A·g^(-1).Impressively,Co-BD||rGO(reduced graphene oxide),representing an asymmetrical supercapacitor,owns a higher energy density of 14.2 Wh·kg^(-1)at 0.80 kW·kg^(-1),and an excellent cycle performance(After 4000 cycles at 1 A·g^(-1),the capacitance retention was up to 94%).CCDC:2418872.
基金the supports from National Natural Science Foundation of China through grant#52002383Ningbo Municipal Bureau of Science and Technology through grant#202003N4365+1 种基金supported by National Natural Science Foundation of China(Grant No.52001012)Beijing Natural Science Foundation(Grant No.2214070).
文摘Cobalt oxide,as one of the most fascinating examples of correlated electronic system,exhibits several exotic transport characteristics,such as superconductivity,charge ordering,and topological frustration.In this study,we are reporting the observation of another intriguing transport phenomenon in calcium cobaltates.Specifically,under a large magnetic field of 7 T,we observed an anomalously enhanced thermal conductivity that was accompanied with a largely suppressed thermopower.This observation reveals a hitherto undiscovered correlation between the two transport factors.Within the premise of Heisenberg model,we have shown that the observed experimental results can be explained consistently only if the magnon excitation is taken into account.Our study offers an insight into the puzzling origin of large thermopower observed in layered cobaltates and provides a specific strategy for further optimization of thermopower.
文摘Hydroformylation of olefins is one of the highest-volume industrial reactions to meet the vast demands for aldehydes as well as their derivatives.Homogeneous Co complexes were the original catalysts industrialized since 1960s.Heterogeneous catalysis is considered superior owing to the facile separation of catalysts from products,shorter technical process,and reduced manufacturing costs.Unexpectedly,there has not been a single case of plant using heterogenized Co-based catalyst successfully.To address the separation issue and understand the catalytic mechanism of the reactions,this review summarizes the progress in heterogeneous systems and provides a detailed discussion of their catalytic performance.Strategies for stabilizing Co species through support modification and additive incorporation are carefully considered to elucidate why heterogeneous systems have not yet succeeded on an industrial scale.Furthermore,we provide our insights for the development of heterogeneous catalytic hydroformylation,including the challenges,opportunities,and outlooks.The aim is to deepen the fundamental understanding of heterogeneous alkene hydroformylation,guiding the community's research efforts towards realizing its successful application in the future.
基金supported by the National Natural Science Foundation of China(No.22171046)the Hundred-Talent Project of Fujian(No.50021113)Fuzhou University(No.0480-00489503)。
文摘In most Suzuki–Miyaura carbon-carbon cross-coupling reactions,the borabicyclo[3.3.1]nonane scaffold(9-BBN)only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products.There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions.Herein,we report a cobalt-catalyzed migratory carboncarbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl-and alkyl-functionalized cyclooctenes.Preliminary mechanistic studies suggest the oxidation-induced cisbicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction,which promotes the development of other diverse migratory cross-coupling of borate complexes.
文摘pH-dependent multiple equilibria in cobalt sulfate-gluconate baths were calculated using stability constants adopted from literature.Changes of the bath speciation were then discussed in terms of spectrophotometric experiments and buffering properties of the solutions(pH 3-10).Cyclic voltammetry indicated changes in electrochemical behavior of cobalt species caused by different ionic compositions of the electrolytes.Tafel slopes were calculated and discussed in relation to electroreduction of cobalt species.Chronoamperometric studies showed 3D instantaneous nucleation of cobalt followed by diffusion-controlled growth,but it was disturbed at higher pH due to the release of cation from gluconate complexes as a limiting step.Diffusion coefficients of cobalt species were found.Changes in the pH were also reflected by modifications of morphology(SEM),development of preferred orientation planes(XRD,texture coefficients)and current efficiency,but not the thickness of the coatings deposited at constant potential of-1.0 V(vs Ag/AgCl).Anodic stripping analysis showed changes in anodic responses originated from the existence of preferentially oriented planes in cobalt layers.
文摘Non-oxidative dehydrogenation of propane(PDH)is an important route for large-scale on purpose propene production.Although cobalt-based catalysts are promising alternatives to currently used platinum-or chromium oxide-based catalysts,their further developments are hindered by the uncertainties related to the kind of the active sites involved in the desired and side reactions.To contribute to closing such a gap,we systematically investigate the role of oxidized CoO_(x) and metallic Co0 species in the PDH reaction over catalysts based in Silicalite-1 with supported CoO_(x) species differing in their redox properties.C_(3)H_(8) pulse experiments with sub-millisecond and second resolution at pulse sizes of about 13 and 2200 nmol,respectively,combined with in-depth catalyst characterization and PDH tests at different propane conversions enabled us to understand how the reaction-induced reduction of CoO_(x) affects product selectivity.Propane readily reacts with CoO_(x) to yield propene,carbon oxides and water.The formed Co0 species show high activity to coking and cracking reactions.However,if the size of such species is below 2 nm,these undesired reactions are significantly hindered due to the coverage of the active sites by carbon-containing species.The remaining uncovered surface Co0 sites selectively dehydrogenate propane to propene.The best-performing catalyst showed higher activity than a commercial-like K-CrOx/Al_(2)O_(3) and operated durable in a series of 10 dehydrogenation/regeneration cycles under industrial relevant conditions.The space time yield of propene formation of 0.97 kg·h^(-1)·kgcat^(-1) was achieved at 550℃,52%equilibrium propane conversion and 95% propene selectivity.
基金the National Key R&D Program of China(No.2022YFA1503200)the National Natural Science Foundation of China(Nos.22025104,22171134,and 21972064)the Fundamental Research Funds for the Central Universities(No.020514380254)is greatly appreciated.
文摘The asymmetric addition of aromatic organometallic compounds to the carbonyl group(C-3)of isatins,catalyzed by transition metals,has emerged as a remarkably efficient method for the synthesis of chiral 3-hydroxyoxindoles.Here,an exceptionally enantioselective approach was developed for the first time to achieve a catalytic NHK reaction of isatins with aromatic halides(both aryl and heteroaryl).Utilizing chiral cobalt complexes as catalysts,and the presence of a diboron reagent B_(2)nep_(2)as both a reducing agent and determinant in enantiocontrol,has resulted in the triumphantly achieved synthesis of enantioenriched products.Compared to reported strategies,this approach exhibits remarkable compatibility with substrates bearing sensitive functional groups,such as halides and borate esters,while also eliminating the need for organometallic reagents as required in previous strategies.Through experimental investigations,the presence of aryl-cobalt species during the addition process was confirmed,rather than in-situ generation of an arylboron reagent.Furthermore,the successful attainment of the R absolute configuration through aryl addition was demonstrated.
基金supported by the NSF of China(22071068)the Instrumental Analysis Center of Huaqiao University.
文摘Transition metal-catalyzed functionalization of unsymmetrical internal alkynes remains challenging because of the difficulty in controlling regioselectivity of migratory insertion of alkynes into the C–metal bonds. Moreover, the synthesis of C–N atropisomers has received significantly less attention compared to that of C–C atropisomers and there have been only a few isolated examples reported for the construction of chiral diaxes through C–H functionalization. Herein, we report that cobalt can catalyze the C–H annulations of aminoquinoline amides with directing group-tethered internal alkynes or 1-indolylalkynes for the synthesis of chiral diaxes. A variety of vicinal C–N and C–C chiral diaxes and distal double C–N chiral diaxes were synthesized with excellent regio, diastereo, and enantioselectivity under mild reaction conditions. The ready availability of aminoquinoline amides, alkynes, and Salox ligands and the simplicity and good functional group tolerance of this protocol make it highly attractive.
基金supported by the National Key R&D Program of China(No.2022YFB3504403).
文摘The origin of the misorientations after fcc(face-centered cubic)to hcp(hexagonal close-packed)transformation in pure cobalt was elucidated by utilizing the electron backscatter diffraction(EBSD)technique and transformation crystallographic models.It is found the Shoji−Nishiyama orientation relationship during fcc→hcp transformation leads to four hcp variants,characterized by a common misorientation angle of 70.5°with respect to the<1120>direction,which is the predominant misorientation observed.Other statistically significant misorientation angles between hcp grains,including 32°,36°,38°,60°,71°and 86°−91°,are also identified.These newly observed misorientation angles are linked to the microstructure of the fcc matrix at elevated temperatures,with twin structures in the fcc matrix being the primary cause.Furthermore,a novel method is proposed for estimating the fraction of twins in the fcc grains based on misorientation angles between hcp variants,which is found to be consistent with experimental observations.In-situ EBSD observations validate the possible origin of fcc twins from the hcp→fcc transformation.
基金support from the Starting Research Funds of Hebei University of Science and Technology,the National Natural Science Foundation of China(22109038)the Hebei Natural Science Foundation(D2022208001)the S&T Program of Hebei(21344601D,242G4601Z)。
文摘Understanding the catalytic mechanism at real catalytically active layer is essential for the advancement of water oxidation.Nevertheless,it is difficult to explore the surface effect of active layer of catalysts on oxygen evolution reaction(OER)independently because of the coexistence of bulk phase and surfaceactive layer.Herein,by designing ultra-thin shell amorphous CoO_(x)hollow nanospheres,we explored the effect of single catalytic active layer on OER activity,further revealing the surface catalytic mechanism for seawater oxidation.The amorphous catalytic active layer CoO_(x)contain phosphates(CoO_(x)PO_(4)),induced by completely bulk reconstruction of CoP_(x)hollow nanospheres.Compared with autologous crystalline CoO,amorphous catalytic active species CoO_(x)-PO_(4)possesses higher OER performance with ultralow overpotential of 229 mV to achieve 10 mA cm^(-2).Remarkably,self-built phosphate film could effectively block chloride anions and implement robust seawater oxidation.This work brings direct insights of the surface effect of amorphous catalytic active layer on water oxidation,which is critical for the performance optimization of water oxidation.
