Searching for novel solid electrolytes is of great importance and challenge for all-solid-state Mg batteries.In this work,we develop an amorphous Mg borohydride ammoniate,Mg(BH_(4))_(2)·2NH_(3),as a solid Mg elec...Searching for novel solid electrolytes is of great importance and challenge for all-solid-state Mg batteries.In this work,we develop an amorphous Mg borohydride ammoniate,Mg(BH_(4))_(2)·2NH_(3),as a solid Mg electrolyte that prepared by a NH_(3)redistribution between 3D framework-γ-Mg(BH_(4))_(2)and Mg(BH_(4))_(2)·6NH_(3).Amorphous Mg(BH_(4))_(2)·2NH_(3)exhibits a high Mg-ion conductivity of 5×10^(-4)S cm^(-1)at 75℃,which is attributed to the fast migration of abundant Mg vacancies according to the theoretical calculations.Moreover,amorphous Mg(BH_(4))_(2)·2NH_(3)shows an apparent electrochemical stability window of 0-1.4 V with the help of in-situ formed interphases,which can prevent further side reactions without hindering the Mg-ion transfer.Based on the above superiorities,amorphous Mg(BH_(4))_(2)·2NH_(3)enables the stable cycling of all-solid-state Mg cells,as the critical current density reaches 3.2 mA cm^(-2)for Mg symmetrical cells and the reversible specific capacity reaches 141 mAh g^(-1)with a coulombic efficiency of 91.7%(first cycle)for Mg||TiS_(2)cells.展开更多
The unique photocatalytic mechanism of S-scheme heterojunction can be used to study new and efficient photocatalysts.By carefully selecting semiconductors for S-scheme heterojunction photocatalysts,it is possible to r...The unique photocatalytic mechanism of S-scheme heterojunction can be used to study new and efficient photocatalysts.By carefully selecting semiconductors for S-scheme heterojunction photocatalysts,it is possible to reduce the rate of photogenerated carrier recombination and increase the conversion efficiency of light into energy.Chalcogenides are a group of compounds that include sulfides and selenides(e.g.,CdS,ZnS,Bi_(2)S_(3),MoS_(2),ZnSe,CdSe,and CuSe).Chalcogenides have attracted considerable attention as heterojunction photocatalysts owing to their narrow bandgap,wide light absorption range,and excellent photoreduction properties.This paper presents a thorough analysis of S-scheme heterojunction photocatalysts based on chalcogenides.Following an introduction to the fundamental characteristics and benefits of S-scheme heterojunction photocatalysts,various chalcogenide-based S-scheme heterojunction photocatalyst synthesis techniques are summarized.These photocatalysts are used in numerous significant photocatalytic reactions,in-cluding the reduction of carbon dioxide,synthesis of hydrogen peroxide,conversion of organic matter,generation of hydrogen from water,nitrogen fixation,degradation of organic pollutants,and sterilization.In addition,cutting-edge characterization techniques,including in situ characterization techniques,are discussed to validate the steady and transient states of photocatalysts with an S-scheme heterojunction.Finally,the design and challenges of chalcogenide-based S-scheme heterojunction photocatalysts are explored and recommended in light of state-of-the-art research.展开更多
Hydrogen energy has emerged as a significant energy source for accomplishing energy transformation and achieving carbon neutrality.Hydrogen production,storage and transportation are the key technologies to realize hyd...Hydrogen energy has emerged as a significant energy source for accomplishing energy transformation and achieving carbon neutrality.Hydrogen production,storage and transportation are the key technologies to realize hydrogen energy application and carbon neutralization goal.Apart from the mature technologies of fossil fuel reforming and water electrolysis,new hydrogen production methods(such as solar photolysis,biomass conversion,thermochemical circulation,etc.)have garnered widespread attention and research interest.The lack of safe and efficient hydrogen storage and utilization technology for hydrogen fuel cell systems is the major obstacle to achieving hydrogen economy.In the past decades,global researchers have conducted extensive studies on enhancing the hydrogen storage performance of materials,such as alloy,metal hydride,complex hydride,carbon-based materials,etc.,as well as the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage carriers.The themed issue entitled“Hydrogen Energy Production,Storage and Utilization”includes 10 carefully selected papers that address the most recent developments in hydrogen production and storage materials,involving catalyst design,structure characterization,hydrogen ab-/desorption performance and mechanism,and fuel cell coupling system exploit.展开更多
The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leaka...The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leakageproofing method.In this study,a novel carbonized Cu-coated melamine foam(MF)/reduced graphene oxide(rGO)framework(MF/rGO/Cu-C)is constructed as a support for fabricating stabilized multifunctional OPCMs.MF serves as the supporting material,while rGO and Cu act as functional reinforcements.As a thermal energy storage material,polyethylene glycol(PEG)is encapsulated into MF/rGO/Cu-C through a vacuum-assisted impregnation method to obtain PEG@MF/rGO/Cu-C composite with excellent comprehensive performance.PEG@MF/rGO/Cu-C exhibits high phase change enthalpies of 148.3 J g^(-1)(melting)and 143.9 J g^(-1)(crystallization),corresponding to a high energy storage capability of 92.7%.Simultaneously,MF/rGO/Cu-C endues the composite with an enhanced thermal conductivity of 0.4621Wm^(-1) K^(-1),which increases by 463%compared to that of PEG@MF.Furthermore,PEG@MF/rGO/Cu-C displays great light-to-thermal and electric-to-thermal conversion capabilities,thermal cycle stability,light-tothermal cycle stability,and shape stability,showing promising application prospects in different aspects.展开更多
Used as high-performance electrodes,both structural and compositional alterations of carbon materials play very important roles in energy conversion/storage devices.Especially in supercapacitors,hierarchical pores and...Used as high-performance electrodes,both structural and compositional alterations of carbon materials play very important roles in energy conversion/storage devices.Especially in supercapacitors,hierarchical pores and heteroatom doping in carbon materials are indispensable.Here the rambutan-like hierarchically porous carbon microspheres(PCMs)have been constructed via a hydrothermal treatment,followed by carbonization/activation.The hierarchically porous microstructure is composed of three-dimensional porous carbon networks,which give rise to a large surface area.Moreover,N and O functional groups are introduced in the as-prepared samples,which could generate the extra pseudocapacitance.Benefitting from the interconnected hierarchical and open structure,PCM exhibits outstanding capacitive performance,for example,superior specific capacitance and rate capability(397 and 288 F g^(−1) at 0.5 and 20A g^(−1),respectively),as well as long cycling stability(about 95%capacitance retention after 10,000 cycles).These encouraging results may pave an efficient way to fabricate advanced supercapacitors in the future.展开更多
Coherent precipitation of cuboidal γ'-Co3(Al,W) nanoparticles in face-centered-cubic (FCC)-γ matrix is of great significance for improving high-temperature mechanical properties of Co-based superalloys. The pres...Coherent precipitation of cuboidal γ'-Co3(Al,W) nanoparticles in face-centered-cubic (FCC)-γ matrix is of great significance for improving high-temperature mechanical properties of Co-based superalloys. The present work developed a series of low-density Co-based superalloys in light of the cluster composition formula of [Al1-(Co,Ni)12]((Al0.5(Ti/Nb/Ta)0.5W0.5)(Mo0.5Cr0.5Co0.5)), where the addition of Ti, Nb, and Ta is mixed with an equimolar ratio. It is found that these designed alloys with different combinations of Ti/Nb/Ta, Ti/Nb, and Ti/Ta possess the coherent microstructure of cuboidal γ' nanoprecipitates in the FCC-γ matrix. The microstructural evolution of coherent γ/γ' during aging at 1173 K shows that these superalloys exhibit higher thermal stability at high temperatures. Even after aging for 1000 h, there do not exist any other precipitated phases on grain boundaries, except the coarse γ' precipitates. Also, the coarsening rate constants of cuboidal γ' nanoprecipitates in these alloys are very low (K = 5.76-6.03 nm3/s), which is mainly ascribed to a moderate lattice misfit (ε = 0.28 %-0.45 %) between γ and γ'. The stable γ/γ' microstructure renders the alloys with prominent mechanical properties, as evidenced by the high yield strength of σYS = 438-445 MPa at 1143 K. A large amount of stacking faults appear after compressive deformation and Lomer-Contrell dislocation locks are also formed due to the reaction of partial dislocations of stacking faults. Moreover, the microhardness (285-320 HV) in each alloy keeps almost constant with the aging time. Besides, these superalloys have a relatively lower density (8.67-8.89 g/cm3), among which the alloy containing Ti0.25Ta0.25 also exhibits a much higher γ' solvus temperature (1361 ± 2 K) than those of the existing Co-Al-W-based superalloys.展开更多
Magnesium hydride(MgH_(2))is an exceptional material for hydrogen storage,but its high desorption temperature and slow kinetics limit its applicability.In this study,the hydrogen storage performance of MgH_(2)was enha...Magnesium hydride(MgH_(2))is an exceptional material for hydrogen storage,but its high desorption temperature and slow kinetics limit its applicability.In this study,the hydrogen storage performance of MgH_(2)was enhanced using highly dispersed Ni-nanoparticle–doped hollow spherical vanadium nitride(Ni/VN),which was synthesized via a solvothermal process.The MgH_(2)system doped with the synthesized Ni/VN exhibited an outstanding hydrogen-storage capability.Specifically,5.6 wt.%of H_(2)was released within 1 h at a relatively low temperature of 513 K,whereas 6.4 wt.%of H_(2)was released within 180 s at 598 K,followed by an almost complete dehydrogenation after 10 min at 598 K.At 423 K,the developed material absorbed~6.0 wt.%of H_(2)within 5 min.The activation energy for dehydrogenation was determined to be 78.07±2.91 k J·mol^(-1),which was considerably lower than that of MgH_(2)produced by ball milling(120.89±5.74 k J·mol^(-1)),corresponding to a reduction of 35.4%.It was deduced that the formation of Mg_(2)Ni/Mg_(2)NiH_(4)(hydrogen pump)through the reaction of Ni nanoparticles during dehydrogenation/hydrogenation facilitated hydrogen transport and synergistically catalyzed hydrogen absorption and desorption by MgH_(2),improving its hydrogen storage capability.These findings offer novel perspectives for the utilization of MgH_(2)in large-scale applications.展开更多
Mg基制氢材料具有来源广泛、反应温和、工艺简单、安全可控、理论产氢量高等优势,是当今的研究热点.本文提出采用高能球磨方法制备Mg-Bi系含氧酸盐Bi_(x)M_(y)O_(z)(M=Ti,V,Cr,Mo,W)复合材料以改善Mg水解制氢性能.本工作研究发现,掺杂Bi...Mg基制氢材料具有来源广泛、反应温和、工艺简单、安全可控、理论产氢量高等优势,是当今的研究热点.本文提出采用高能球磨方法制备Mg-Bi系含氧酸盐Bi_(x)M_(y)O_(z)(M=Ti,V,Cr,Mo,W)复合材料以改善Mg水解制氢性能.本工作研究发现,掺杂Bi_(2)Mo O_(6)的Mg基复合制氢材料具有较好的性能,Mg-7 wt%Bi_(2)Mo O_(6)在298.15 K的最大产氢速率为756.1 m L g^(-1)min(-1).通过引入多壁碳纳米管(CNTs)可以进一步改善Mg-Bi_(2)Mo O_(6)的产氢性能,Mg-7 wt%Bi_(2)Mo O_(6)/CNTs的最大产氢速率达2172.4 m L g^(-1)min(-1),产氢活化能下降至23.6 k J mol^(-1).X光电子能谱(XPS)分析表明Bi_(2)Mo O_(6)/CNTs与Mg在球磨过程中发生固相反应生成Bi单质.密度泛函理论(DFT)计算揭示Bi原子掺杂可改变Mg的局域电荷分布,增强Mg对H_(2)O的吸附能,并降低H_(2)O解离后H原子的吸附能,促进水解反应进行.展开更多
The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)...The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.0016.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed.展开更多
In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon materia...In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon material was prepared through one-pot co-assembly method, using resorcinol and formaldehyde as carbon precursor, tetraethoxysilane as silica sources and triblock copolymer F127 as a template. And the phase behaviors of n-octadcane confined in the nano-porous structure of the meso-porous carbon were further investigated. Fourier transform-infrared spectroscopy spectra show that n-octadecane was effectively encapsulated in the porous structure of mesoporous carbon and the composite PCMs were successfully prepared. Differential scanning calorimetry results confirm that the composite PCMs possess a good phase change behavior, fast thermal-response rate and excellent thermal cycling stability. In addition, the composite PCMs possess expected heat storage and heat release properties. All these results demonstrate that the composite PCMs possess good comprehensive property so that they can be used widely in energy storage systems.展开更多
The urgent need of high-performance of energy storage devices triggers us to design newly class of materials.Generally,the materials feature with high conductivity,abundant pore s and excellent stability.Here,a sandwi...The urgent need of high-performance of energy storage devices triggers us to design newly class of materials.Generally,the materials feature with high conductivity,abundant pore s and excellent stability.Here,a sandwiched hybrid composite containing reduced graphene oxide,polypyrrole and Ni-Co layered double hydroxides(RGO/PPy/NiCo-LDH) was prepared in a facile way.The polypyrrole was incorporated in the two dimensional(2D) nanosheets,which not only serve as the spacer to increase the surface area,but also enhance the conductivity of the nanocomposite.The obtained architecture was employed as an advanced electrode in a supercapacitor.The electrode shows an ultrahigh specific capacitance(2534 F g^-1 at 1 A g^-1) and good cycling efficiency(78 % after 5000 cycles).Moreover,an asymmetric cell based RGO/PPy/NiCo-LDH composite demonstrates excellent electrochemical properties and good prospect of practical use.展开更多
Two new 3 D metal-organic frameworks（MOFs） named [Pr2（PDA）3-3 H2 O]-H2 O（1） and[Nd2（PDA）3-3 H2 O] H2 O（2） [2,6-Pyridinedicarboxylic acid（H2 PDA）] were synthesized by solvothermal method. They were characte...Two new 3 D metal-organic frameworks（MOFs） named [Pr2（PDA）3-3 H2 O]-H2 O（1） and[Nd2（PDA）3-3 H2 O] H2 O（2） [2,6-Pyridinedicarboxylic acid（H2 PDA）] were synthesized by solvothermal method. They were characterized by elemental analyses（EA）, infrared spectroscopy（FT-IR）, thermogravimetric analysis（TG）, photocatalysis performance and single crystal X-ray diffraction studies（XRD）.The XRD analysis indicated that MOFs（1） and（2） both belong to the monoclinic system with space group P2（1）/C. The structural model were drawn by the diamond software, and the structure revel that MOFs（1） and（2） adopt three-dimensional（3 D） frameworks constructed by cross-linking of one-dimensional（1 D） infinite chain secondary building unit（SBU） by 2,6-Pyridinedicarboxylic acid and hydrogen bond as linker. These frameworks feature channels inside which coordinated H20 solvent molecules are located. Thermogravimetric analysis showed that both MOFs are thermally stable, the photocatalytic evaluation showed the materials have a good prospect in degration methylene blue. As for complex1, the decomposition efficiency of Methylene blue was about 91.08% after 130 min and the complex 2 reach 90.45% after 160 min under the sun light.展开更多
Efficient technical strategies to synthesize hydrides with high capacity and favorable reversibility are significant for the development of novel energy materials.Herein,nano Mg-based borohydride,Mg(BH_(4))_(2),with r...Efficient technical strategies to synthesize hydrides with high capacity and favorable reversibility are significant for the development of novel energy materials.Herein,nano Mg-based borohydride,Mg(BH_(4))_(2),with robust architecture was designed and prepared by confining on graphene through a solution selfconfinement method.The Mg(BH_(4))_(2) confined on graphene displays a wrinkled 2D nano layer morphology within 8.8 nm thickness.Such 2D nano Mg(BH_(4))_(2) can start dehydrogenation at 67.9℃ with a high capacity of 12.0 wt.%,which is 190.5℃ lower than pristine Mg(BH_(4))_(2).The isothermal dehydrogenation tests and kinetics fitting results indicate the 2D nano Mg(BH_(4))_(2) possesses much-enhanced dehydrogenation kinetics of 31.3 kJ/mol activation energy,which is only half of pristine Mg(BH_(4))_(2).The thermodynamics of the 2D nano Mg(BH_(4))_(2) is also verified by PCT tests,of which Gibbs free energy value for the confined 2D nano Mg(BH_(4))_(2) is estimated to be-18.01 kJ/mol H_(2),lower than-16.36 kJ/mol H_(2) of pristine Mg(BH_(4))_(2).Importantly,the reversibility of the confined 2D nano Mg(BH_(4))_(2) is significantly enhanced to over 90%capacity retention with relatively kinetics stability during 10 cycles.The mechanism analyses manifest that Mg(BH_(4))_(2) exhibits stable 2D nano morphology during 10 cyclic tests,resulting in the greatly reduced H diffusion path and the improved de/rehydrogenation kinetics of the 2D nano Mg(BH_(4))_(2).Based on theoretical calculations of Mg(BH_(4))_(2) and the intermediate MgB12H12 confined on graphene,the charge transfer status of both samples is modified to facilitate de/rehydrogenation,thus leading to the significant thermodynamic improvements of the reversible hydrogen storage performances for 2D nano Mg(BH_(4))_(2).Such investigation of the Mg-based borohydride will illuminate prospective technical research of energy storage materials.展开更多
Ultrafine carbon-based transition metal compounds have been widely investigated as efficient catalysts for enhancing the hydrogen storage performance of magnesium hydride.In this work,the carbon ther-mal shock method ...Ultrafine carbon-based transition metal compounds have been widely investigated as efficient catalysts for enhancing the hydrogen storage performance of magnesium hydride.In this work,the carbon ther-mal shock method is applied to synthesize the ultrafine carbon-encapsulated NbC nanoparticles with an average grain size of 17.3 nm.The MgH_(2)-10 wt%NbC/C composites show excellent low-temperature hy-drogen storage performance with the onset dehydrogenation temperature of 196.1℃,which is 92.2℃ and 98℃ lower than that of MgH_(2)-10 wt%NbC and undoped MgH_(2),respectively.Specifically,MgH_(2)-10 wt%NbC/C can absorb 6.71 wt%H_(2) at 100℃ within 30 min around and retain almost 100%reversible hydrogen desorption capacity after 10 cycles.For the catalytic mechanism,the electron transfer process between multi-valence Nb cations of in-situ formed NbH x and Mg,H atoms can greatly improve the cyclic de/rehydrogenation kinetics of MgH_(2)-NbC/C.Besides,the enhancement of dehydrogenation kinetics can also be ascribed to MgH_(2) particle refinement by NbC nanoparticles,and destabilization of the Mg-H bond caused by carbon substrate.This investigation not only proves that carbon-encapsulated NbC nanoparti-cles can greatly enhance the hydrogen storage performance of MgH_(2) but provides an idea of preparing carbon-based transition metal carbides as effective catalysts for magnesium-based hydrogen storage ma-terials.展开更多
Coordination polymer Co-btca （H4btca = 1,2,4,5-benzenetetracarbo ylic acid） was synthesized using a simply hydrothermal method. In particular, the as-prepared Co-btca was applied as an anode material for lithium-ion...Coordination polymer Co-btca （H4btca = 1,2,4,5-benzenetetracarbo ylic acid） was synthesized using a simply hydrothermal method. In particular, the as-prepared Co-btca was applied as an anode material for lithium-ion battery for the first time. Single crystal X-ray diffraction results indicated that the as- prepared Co-btca displayed unique layer structure, which was beneficial to transport Li ions and electrons. Also, owing to the porous structure and appropriate specific surface area, Co-btca electrode delivered a reversible capacity of 801.3 mA h/g after 50 cycles at a current density of 200 mA/g. The reversible capacity of 773.9 mA h/g was maintained after 200 cycles at a current density of 500 mA/g, exhibiting enhanced cycle stability. It also showed improved rate performance, making it a promising anode material and a new choice for lithium-ion batteries.展开更多
Heteroatom doped graphitic porous carbon is highly desirable for electrochemical applications because of its excellent conductivity and high surface area.In this study,highly uniform Co-Ni oxide nanoparticleloaded B,N...Heteroatom doped graphitic porous carbon is highly desirable for electrochemical applications because of its excellent conductivity and high surface area.In this study,highly uniform Co-Ni oxide nanoparticleloaded B,N-doped hierarchical graphitic porous carbon was prepared through a dual pyrolysis process.Graphene dispersed chitosan hydrogel was first used as a precursor to fabricate the porous carbon(GCS–C)at 700℃.Co and Ni oxide nanoparticles were further anchored on the porous carbon through chemical reduction and calcined at high temperature.The structure of the porous carbon was optimized by the introduction of graphene to the chitosan hydrogel.The graphitic degree of the porous carbon was significantly improved by the Co and Ni species.The heteroatom B and N were found to be well doped in the composite.These features enable the composite to be an excellent candidate for supercapacitor electrodes.The composite demonstrates a high capacitance(1266.7 F g-1 at 1 A g-1)and excellent stability.展开更多
基金the support of the National Natural Science Foundation of China(51971146,51971147,52171218 and 52271222)the Shanghai Municipal Science and Technology Commission(21010503100)+3 种基金the Major Program for the Scientific Research Innovation Plan of Shanghai Education Commission(2019-01-07-00-07E00015)the Shanghai Outstanding Academic Leaders Plan,the Guangxi Key Laboratory of Information Materials(Guilin University of Electronic Technology,201017-K)the Shanghai Rising-Star Program(20QA1407100)the General Program of Natural Science Foundation of Shanghai(20ZR1438400)
文摘Searching for novel solid electrolytes is of great importance and challenge for all-solid-state Mg batteries.In this work,we develop an amorphous Mg borohydride ammoniate,Mg(BH_(4))_(2)·2NH_(3),as a solid Mg electrolyte that prepared by a NH_(3)redistribution between 3D framework-γ-Mg(BH_(4))_(2)and Mg(BH_(4))_(2)·6NH_(3).Amorphous Mg(BH_(4))_(2)·2NH_(3)exhibits a high Mg-ion conductivity of 5×10^(-4)S cm^(-1)at 75℃,which is attributed to the fast migration of abundant Mg vacancies according to the theoretical calculations.Moreover,amorphous Mg(BH_(4))_(2)·2NH_(3)shows an apparent electrochemical stability window of 0-1.4 V with the help of in-situ formed interphases,which can prevent further side reactions without hindering the Mg-ion transfer.Based on the above superiorities,amorphous Mg(BH_(4))_(2)·2NH_(3)enables the stable cycling of all-solid-state Mg cells,as the critical current density reaches 3.2 mA cm^(-2)for Mg symmetrical cells and the reversible specific capacity reaches 141 mAh g^(-1)with a coulombic efficiency of 91.7%(first cycle)for Mg||TiS_(2)cells.
文摘The unique photocatalytic mechanism of S-scheme heterojunction can be used to study new and efficient photocatalysts.By carefully selecting semiconductors for S-scheme heterojunction photocatalysts,it is possible to reduce the rate of photogenerated carrier recombination and increase the conversion efficiency of light into energy.Chalcogenides are a group of compounds that include sulfides and selenides(e.g.,CdS,ZnS,Bi_(2)S_(3),MoS_(2),ZnSe,CdSe,and CuSe).Chalcogenides have attracted considerable attention as heterojunction photocatalysts owing to their narrow bandgap,wide light absorption range,and excellent photoreduction properties.This paper presents a thorough analysis of S-scheme heterojunction photocatalysts based on chalcogenides.Following an introduction to the fundamental characteristics and benefits of S-scheme heterojunction photocatalysts,various chalcogenide-based S-scheme heterojunction photocatalyst synthesis techniques are summarized.These photocatalysts are used in numerous significant photocatalytic reactions,in-cluding the reduction of carbon dioxide,synthesis of hydrogen peroxide,conversion of organic matter,generation of hydrogen from water,nitrogen fixation,degradation of organic pollutants,and sterilization.In addition,cutting-edge characterization techniques,including in situ characterization techniques,are discussed to validate the steady and transient states of photocatalysts with an S-scheme heterojunction.Finally,the design and challenges of chalcogenide-based S-scheme heterojunction photocatalysts are explored and recommended in light of state-of-the-art research.
文摘Hydrogen energy has emerged as a significant energy source for accomplishing energy transformation and achieving carbon neutrality.Hydrogen production,storage and transportation are the key technologies to realize hydrogen energy application and carbon neutralization goal.Apart from the mature technologies of fossil fuel reforming and water electrolysis,new hydrogen production methods(such as solar photolysis,biomass conversion,thermochemical circulation,etc.)have garnered widespread attention and research interest.The lack of safe and efficient hydrogen storage and utilization technology for hydrogen fuel cell systems is the major obstacle to achieving hydrogen economy.In the past decades,global researchers have conducted extensive studies on enhancing the hydrogen storage performance of materials,such as alloy,metal hydride,complex hydride,carbon-based materials,etc.,as well as the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage carriers.The themed issue entitled“Hydrogen Energy Production,Storage and Utilization”includes 10 carefully selected papers that address the most recent developments in hydrogen production and storage materials,involving catalyst design,structure characterization,hydrogen ab-/desorption performance and mechanism,and fuel cell coupling system exploit.
基金National Natural Science Foundation of China,Grant/Award Numbers:51861005,52071092,U20A20237Guangxi Natural Science Foundation,Grant/Award Numbers:2019GXNSFDA245023,2019GXNSFGA245005,2020GXNSFGA297004,2021GXNSFFA196002Guangxi Bagui Scholar Foundation。
文摘The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leakageproofing method.In this study,a novel carbonized Cu-coated melamine foam(MF)/reduced graphene oxide(rGO)framework(MF/rGO/Cu-C)is constructed as a support for fabricating stabilized multifunctional OPCMs.MF serves as the supporting material,while rGO and Cu act as functional reinforcements.As a thermal energy storage material,polyethylene glycol(PEG)is encapsulated into MF/rGO/Cu-C through a vacuum-assisted impregnation method to obtain PEG@MF/rGO/Cu-C composite with excellent comprehensive performance.PEG@MF/rGO/Cu-C exhibits high phase change enthalpies of 148.3 J g^(-1)(melting)and 143.9 J g^(-1)(crystallization),corresponding to a high energy storage capability of 92.7%.Simultaneously,MF/rGO/Cu-C endues the composite with an enhanced thermal conductivity of 0.4621Wm^(-1) K^(-1),which increases by 463%compared to that of PEG@MF.Furthermore,PEG@MF/rGO/Cu-C displays great light-to-thermal and electric-to-thermal conversion capabilities,thermal cycle stability,light-tothermal cycle stability,and shape stability,showing promising application prospects in different aspects.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51863005,51462006,51102230,51671062,51871065,and 51971068)the Guangxi Natural Science Foundation(No.2018GXNSFDA281051,2014GXNSFAA118401,and 2020GXNSFGA297004)+2 种基金the Science Research and Technology Development Program of Guangxi(AD17195073,AA19182014 and AA17202030-1)the Guangxi Bagui Scholar Foundation,the Guangxi Collabora-tive Innovation Centre of Structure and Property for New Energy and Materials,the Guangxi Advanced Functional Materials Foundation and Application Talents Small Highlands,Chinesisch-Deutsche Kooperationsgruppe(GZ1528)the Innovation Project of GUET Graduate Education(2019YCXS114 and 2018YJCX88).
文摘We deviseda functional form stable compositephase-change materials(PCMs)toachieve a three-dimensional(3D)interconnectedporous carbon aerogel structure for encapsulating polyethyleneglycol(PEG).Anovelhomogeneity reinforced carbonaerogel witha well-interconnected porous structure was constructed bycombining a flexible carbonresource from biomass guar gum with hard-brittle carbonfrom polyimide,to overcome severeshrinkage andpoor mechanical performance of traditionalcarbon aerogel.Thesupportingcarbon aerogel-encapsulated PEG produced thenovel composite PCMswithgood structure stability andcomprehensive energy storage performance.Theresults showed thatthecomposite PCMsdisplayed awell-defined 3Dinterconnected structure,and theirenergy storage capacities were 171.5 and169.5 J/g,which changed onlyslightlyafter 100 thermalcycles,andthe compositescould maintainthe equilibrium temperature at50.0−58.1℃ for about 760.3 s.The thermal conductivityofthe compositescould reach0.62 W m^(−1) K^(−1),which effectively enhanced the thermalresponse rate.And thecomposite PCMs exhibited good leakage-proof performance andexcellent light–thermal conversion.The compressive strengthof thecomposite PCMscan improveupto 1.602 MPa.Results indicatethatthisstrategy canbe efficiently usedtodevelop novel composite PCMswithimproved comprehensive thermalperformance and high light–thermal conversion.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant Nos.21965007,51671062,and 51871065)the Guangxi Natural Science Foundation(Grant No.2018GXNSFFA281005)+1 种基金the Scientific Research and Technology Development Program of Guangxi(Grant Nos.AA19182014 and AA17202030-1)Guangxi Bagui Scholar Foundation,Guangxi Advanced Functional Materials Foundation and Application Talents Small Highlands,and Chinesisch-Deutsche Kooperationsgruppe(Grant No.GZ1528).
文摘Used as high-performance electrodes,both structural and compositional alterations of carbon materials play very important roles in energy conversion/storage devices.Especially in supercapacitors,hierarchical pores and heteroatom doping in carbon materials are indispensable.Here the rambutan-like hierarchically porous carbon microspheres(PCMs)have been constructed via a hydrothermal treatment,followed by carbonization/activation.The hierarchically porous microstructure is composed of three-dimensional porous carbon networks,which give rise to a large surface area.Moreover,N and O functional groups are introduced in the as-prepared samples,which could generate the extra pseudocapacitance.Benefitting from the interconnected hierarchical and open structure,PCM exhibits outstanding capacitive performance,for example,superior specific capacitance and rate capability(397 and 288 F g^(−1) at 0.5 and 20A g^(−1),respectively),as well as long cycling stability(about 95%capacitance retention after 10,000 cycles).These encouraging results may pave an efficient way to fabricate advanced supercapacitors in the future.
基金financially supported by the National Natural Science Foundation of China(Nos.52171152,91860108 and U1867201)the Key Discipline and Major Project of Dalian Science and Technology Innovation Foundation(No.2020JJ25CY004)+1 种基金Guangxi Key Laboratory of Information Laboratory Foundation(No.221013-K)Peter K.Liaw very much appreciates the support from the National Science Foundation(Nos.DMR-1611180,1809640,and 2226508).
文摘Coherent precipitation of cuboidal γ'-Co3(Al,W) nanoparticles in face-centered-cubic (FCC)-γ matrix is of great significance for improving high-temperature mechanical properties of Co-based superalloys. The present work developed a series of low-density Co-based superalloys in light of the cluster composition formula of [Al1-(Co,Ni)12]((Al0.5(Ti/Nb/Ta)0.5W0.5)(Mo0.5Cr0.5Co0.5)), where the addition of Ti, Nb, and Ta is mixed with an equimolar ratio. It is found that these designed alloys with different combinations of Ti/Nb/Ta, Ti/Nb, and Ti/Ta possess the coherent microstructure of cuboidal γ' nanoprecipitates in the FCC-γ matrix. The microstructural evolution of coherent γ/γ' during aging at 1173 K shows that these superalloys exhibit higher thermal stability at high temperatures. Even after aging for 1000 h, there do not exist any other precipitated phases on grain boundaries, except the coarse γ' precipitates. Also, the coarsening rate constants of cuboidal γ' nanoprecipitates in these alloys are very low (K = 5.76-6.03 nm3/s), which is mainly ascribed to a moderate lattice misfit (ε = 0.28 %-0.45 %) between γ and γ'. The stable γ/γ' microstructure renders the alloys with prominent mechanical properties, as evidenced by the high yield strength of σYS = 438-445 MPa at 1143 K. A large amount of stacking faults appear after compressive deformation and Lomer-Contrell dislocation locks are also formed due to the reaction of partial dislocations of stacking faults. Moreover, the microhardness (285-320 HV) in each alloy keeps almost constant with the aging time. Besides, these superalloys have a relatively lower density (8.67-8.89 g/cm3), among which the alloy containing Ti0.25Ta0.25 also exhibits a much higher γ' solvus temperature (1361 ± 2 K) than those of the existing Co-Al-W-based superalloys.
基金financially supported by the National Natural Science Foundation of China(NSFC)(Grants no 52161036,52071092)the Guangxi Bagui Scholar Foundation。
文摘Magnesium hydride(MgH_(2))is an exceptional material for hydrogen storage,but its high desorption temperature and slow kinetics limit its applicability.In this study,the hydrogen storage performance of MgH_(2)was enhanced using highly dispersed Ni-nanoparticle–doped hollow spherical vanadium nitride(Ni/VN),which was synthesized via a solvothermal process.The MgH_(2)system doped with the synthesized Ni/VN exhibited an outstanding hydrogen-storage capability.Specifically,5.6 wt.%of H_(2)was released within 1 h at a relatively low temperature of 513 K,whereas 6.4 wt.%of H_(2)was released within 180 s at 598 K,followed by an almost complete dehydrogenation after 10 min at 598 K.At 423 K,the developed material absorbed~6.0 wt.%of H_(2)within 5 min.The activation energy for dehydrogenation was determined to be 78.07±2.91 k J·mol^(-1),which was considerably lower than that of MgH_(2)produced by ball milling(120.89±5.74 k J·mol^(-1)),corresponding to a reduction of 35.4%.It was deduced that the formation of Mg_(2)Ni/Mg_(2)NiH_(4)(hydrogen pump)through the reaction of Ni nanoparticles during dehydrogenation/hydrogenation facilitated hydrogen transport and synergistically catalyzed hydrogen absorption and desorption by MgH_(2),improving its hydrogen storage capability.These findings offer novel perspectives for the utilization of MgH_(2)in large-scale applications.
文摘Mg基制氢材料具有来源广泛、反应温和、工艺简单、安全可控、理论产氢量高等优势,是当今的研究热点.本文提出采用高能球磨方法制备Mg-Bi系含氧酸盐Bi_(x)M_(y)O_(z)(M=Ti,V,Cr,Mo,W)复合材料以改善Mg水解制氢性能.本工作研究发现,掺杂Bi_(2)Mo O_(6)的Mg基复合制氢材料具有较好的性能,Mg-7 wt%Bi_(2)Mo O_(6)在298.15 K的最大产氢速率为756.1 m L g^(-1)min(-1).通过引入多壁碳纳米管(CNTs)可以进一步改善Mg-Bi_(2)Mo O_(6)的产氢性能,Mg-7 wt%Bi_(2)Mo O_(6)/CNTs的最大产氢速率达2172.4 m L g^(-1)min(-1),产氢活化能下降至23.6 k J mol^(-1).X光电子能谱(XPS)分析表明Bi_(2)Mo O_(6)/CNTs与Mg在球磨过程中发生固相反应生成Bi单质.密度泛函理论(DFT)计算揭示Bi原子掺杂可改变Mg的局域电荷分布,增强Mg对H_(2)O的吸附能,并降低H_(2)O解离后H原子的吸附能,促进水解反应进行.
基金financially supported by the National Key Research and Development Plan(No.2017YFB0702400)the Science Challenge Project(No.TZ2016004)+1 种基金the National Magnetic Confinement Fusion Energy Research Project(No.2015GB121004)the Foundation of Guangxi Key Laboratory of Information Materials(No.161002-K)
文摘The multi-component composition characteristics of high-temperature near-α Ti alloys were investigated in the present work by means of a cluster formula approach. The uniform cluster formula [CN12 cluster](glue atom)3 for the hexagonal close-packed α solid solution was first obtained based on the Friedel oscillation theory, with a total atom number in the formula of Z = 16. Then it was analyzed that the Z values in the cluster composition formulas of typical near-α Ti alloys are within the range of Z = 16.0016.30, being perfectly consistent with the ideal Z = 16. Based on it, a series of new alloys with Z = 16 and with Nb/Ta substitution for Mo in Ti1100 alloy were designed, suction-cast into φ 6 mm rods, and then heat-treated with solid solution and aging. It was found that the alloy with co-addition of Mo, Ta and Nb has a high strength and good ductility at both room and high temperatures. More importantly, the additions of Nb and Ta can contribute to the formation of continuous and compact Al2O3 scales, resulting in an obvious improvement of oxidation resistances at both 923 K and 1073 K. The effects of Mo, Ta and Nb on the oxidation behaviors of the designed alloys at 1073 K were further discussed.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51102230, 51462006, 51361005, 51863005, U1501242, 51371060 and 51671062)the Guangxi Natural Science Foundation (Nos. 2014GXNSFAA118401, 2013GXNSFBA019244, 2014GXNSFAA118319 and 2014GXNAFDA118005)+2 种基金Guangxi Key Laboratory of Information Materials (Nos. 161002-Z, 171027-Z and 161002-K)Guangxi Scientific Technology Team (No. 2012GXNSFGA06002, AA17202030)the Program for Postgraduate Joint Training Base of GUET-CJYRE (No. 20160513-14-Z)
文摘In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon material was prepared through one-pot co-assembly method, using resorcinol and formaldehyde as carbon precursor, tetraethoxysilane as silica sources and triblock copolymer F127 as a template. And the phase behaviors of n-octadcane confined in the nano-porous structure of the meso-porous carbon were further investigated. Fourier transform-infrared spectroscopy spectra show that n-octadecane was effectively encapsulated in the porous structure of mesoporous carbon and the composite PCMs were successfully prepared. Differential scanning calorimetry results confirm that the composite PCMs possess a good phase change behavior, fast thermal-response rate and excellent thermal cycling stability. In addition, the composite PCMs possess expected heat storage and heat release properties. All these results demonstrate that the composite PCMs possess good comprehensive property so that they can be used widely in energy storage systems.
基金This work was supported by the National Natural Science Foundation of China(Nos.51861005 and 51861004)the Innovation Project of Guangxi Graduate Education(No.YCSW2019149)Guangxi Natural Science Foundation(No.2017AD23029)。
文摘The urgent need of high-performance of energy storage devices triggers us to design newly class of materials.Generally,the materials feature with high conductivity,abundant pore s and excellent stability.Here,a sandwiched hybrid composite containing reduced graphene oxide,polypyrrole and Ni-Co layered double hydroxides(RGO/PPy/NiCo-LDH) was prepared in a facile way.The polypyrrole was incorporated in the two dimensional(2D) nanosheets,which not only serve as the spacer to increase the surface area,but also enhance the conductivity of the nanocomposite.The obtained architecture was employed as an advanced electrode in a supercapacitor.The electrode shows an ultrahigh specific capacitance(2534 F g^-1 at 1 A g^-1) and good cycling efficiency(78 % after 5000 cycles).Moreover,an asymmetric cell based RGO/PPy/NiCo-LDH composite demonstrates excellent electrochemical properties and good prospect of practical use.
基金financial supports from the NSFC (51361005, U1501242, 51371060 and 51671062)Guangxi Natural Science Foundation (2014GXNSFAA118319, 2014GXNAFDA118005)+1 种基金Guangxi Key Laboratory of Information Materials (161002-Z, 161002-K)Guangxi Scientific Technology Team (2012GXNSFGA06002)
文摘Two new 3 D metal-organic frameworks（MOFs） named [Pr2（PDA）3-3 H2 O]-H2 O（1） and[Nd2（PDA）3-3 H2 O] H2 O（2） [2,6-Pyridinedicarboxylic acid（H2 PDA）] were synthesized by solvothermal method. They were characterized by elemental analyses（EA）, infrared spectroscopy（FT-IR）, thermogravimetric analysis（TG）, photocatalysis performance and single crystal X-ray diffraction studies（XRD）.The XRD analysis indicated that MOFs（1） and（2） both belong to the monoclinic system with space group P2（1）/C. The structural model were drawn by the diamond software, and the structure revel that MOFs（1） and（2） adopt three-dimensional（3 D） frameworks constructed by cross-linking of one-dimensional（1 D） infinite chain secondary building unit（SBU） by 2,6-Pyridinedicarboxylic acid and hydrogen bond as linker. These frameworks feature channels inside which coordinated H20 solvent molecules are located. Thermogravimetric analysis showed that both MOFs are thermally stable, the photocatalytic evaluation showed the materials have a good prospect in degration methylene blue. As for complex1, the decomposition efficiency of Methylene blue was about 91.08% after 130 min and the complex 2 reach 90.45% after 160 min under the sun light.
基金supported by the National Natural Science Foundation of China(Nos.52171223 and U20A20237)the Zhejiang Provincial Natural Science Foundation of China(No.LZ21E010002).
文摘Efficient technical strategies to synthesize hydrides with high capacity and favorable reversibility are significant for the development of novel energy materials.Herein,nano Mg-based borohydride,Mg(BH_(4))_(2),with robust architecture was designed and prepared by confining on graphene through a solution selfconfinement method.The Mg(BH_(4))_(2) confined on graphene displays a wrinkled 2D nano layer morphology within 8.8 nm thickness.Such 2D nano Mg(BH_(4))_(2) can start dehydrogenation at 67.9℃ with a high capacity of 12.0 wt.%,which is 190.5℃ lower than pristine Mg(BH_(4))_(2).The isothermal dehydrogenation tests and kinetics fitting results indicate the 2D nano Mg(BH_(4))_(2) possesses much-enhanced dehydrogenation kinetics of 31.3 kJ/mol activation energy,which is only half of pristine Mg(BH_(4))_(2).The thermodynamics of the 2D nano Mg(BH_(4))_(2) is also verified by PCT tests,of which Gibbs free energy value for the confined 2D nano Mg(BH_(4))_(2) is estimated to be-18.01 kJ/mol H_(2),lower than-16.36 kJ/mol H_(2) of pristine Mg(BH_(4))_(2).Importantly,the reversibility of the confined 2D nano Mg(BH_(4))_(2) is significantly enhanced to over 90%capacity retention with relatively kinetics stability during 10 cycles.The mechanism analyses manifest that Mg(BH_(4))_(2) exhibits stable 2D nano morphology during 10 cyclic tests,resulting in the greatly reduced H diffusion path and the improved de/rehydrogenation kinetics of the 2D nano Mg(BH_(4))_(2).Based on theoretical calculations of Mg(BH_(4))_(2) and the intermediate MgB12H12 confined on graphene,the charge transfer status of both samples is modified to facilitate de/rehydrogenation,thus leading to the significant thermodynamic improvements of the reversible hydrogen storage performances for 2D nano Mg(BH_(4))_(2).Such investigation of the Mg-based borohydride will illuminate prospective technical research of energy storage materials.
基金supported by the National Natural Science Foundation of China (No.U20A20237)the Zhejiang Provincial Nat-ural Science Foundation of China (No.LZ21E010002).
文摘Ultrafine carbon-based transition metal compounds have been widely investigated as efficient catalysts for enhancing the hydrogen storage performance of magnesium hydride.In this work,the carbon ther-mal shock method is applied to synthesize the ultrafine carbon-encapsulated NbC nanoparticles with an average grain size of 17.3 nm.The MgH_(2)-10 wt%NbC/C composites show excellent low-temperature hy-drogen storage performance with the onset dehydrogenation temperature of 196.1℃,which is 92.2℃ and 98℃ lower than that of MgH_(2)-10 wt%NbC and undoped MgH_(2),respectively.Specifically,MgH_(2)-10 wt%NbC/C can absorb 6.71 wt%H_(2) at 100℃ within 30 min around and retain almost 100%reversible hydrogen desorption capacity after 10 cycles.For the catalytic mechanism,the electron transfer process between multi-valence Nb cations of in-situ formed NbH x and Mg,H atoms can greatly improve the cyclic de/rehydrogenation kinetics of MgH_(2)-NbC/C.Besides,the enhancement of dehydrogenation kinetics can also be ascribed to MgH_(2) particle refinement by NbC nanoparticles,and destabilization of the Mg-H bond caused by carbon substrate.This investigation not only proves that carbon-encapsulated NbC nanoparti-cles can greatly enhance the hydrogen storage performance of MgH_(2) but provides an idea of preparing carbon-based transition metal carbides as effective catalysts for magnesium-based hydrogen storage ma-terials.
基金the financial support from the National Natural Science Foundation of China(Nos.51361005,U1501242,51371060 and 51671062)the Guangxi Natural Science Foundation(Nos.2014GXNSFAA118319,2014GXNAFDA118005)+1 种基金the Guangxi Key Laboratory of Information Materials(Nos.161002Z,161002-K,161003-K)the Guangxi Scientific Technology Team(No.2012GXNSFGA06002)
文摘Coordination polymer Co-btca （H4btca = 1,2,4,5-benzenetetracarbo ylic acid） was synthesized using a simply hydrothermal method. In particular, the as-prepared Co-btca was applied as an anode material for lithium-ion battery for the first time. Single crystal X-ray diffraction results indicated that the as- prepared Co-btca displayed unique layer structure, which was beneficial to transport Li ions and electrons. Also, owing to the porous structure and appropriate specific surface area, Co-btca electrode delivered a reversible capacity of 801.3 mA h/g after 50 cycles at a current density of 200 mA/g. The reversible capacity of 773.9 mA h/g was maintained after 200 cycles at a current density of 500 mA/g, exhibiting enhanced cycle stability. It also showed improved rate performance, making it a promising anode material and a new choice for lithium-ion batteries.
基金the financial support from the National Natural Science Foundation of China(Nos.51861005 and 51861004)the Innovation Project of GUET Graduate Education(2019YCXS113)+1 种基金the GUET Excellent Graduate Thesis Program(17YJPYSS32)the Guangxi Natural Science Foundation(2017AD23029).
文摘Heteroatom doped graphitic porous carbon is highly desirable for electrochemical applications because of its excellent conductivity and high surface area.In this study,highly uniform Co-Ni oxide nanoparticleloaded B,N-doped hierarchical graphitic porous carbon was prepared through a dual pyrolysis process.Graphene dispersed chitosan hydrogel was first used as a precursor to fabricate the porous carbon(GCS–C)at 700℃.Co and Ni oxide nanoparticles were further anchored on the porous carbon through chemical reduction and calcined at high temperature.The structure of the porous carbon was optimized by the introduction of graphene to the chitosan hydrogel.The graphitic degree of the porous carbon was significantly improved by the Co and Ni species.The heteroatom B and N were found to be well doped in the composite.These features enable the composite to be an excellent candidate for supercapacitor electrodes.The composite demonstrates a high capacitance(1266.7 F g-1 at 1 A g-1)and excellent stability.
