Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is fe...Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of(111) surfaces, compressive c-axis strain,and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.展开更多
层状过渡金属氧化物由于其较高的理论比容量和较低的经济成本,被视为一种具有良好应用前景的钠离子电池正极材料。采用溶胶-凝胶法和热处理的方式,制备Ca/Cu共掺杂的铁锰基层状氧化物(O3-Na_(0.9)Ca_(0.05)Fe_(0.45)Mn_(0.45)Cu_(0.1O)_...层状过渡金属氧化物由于其较高的理论比容量和较低的经济成本,被视为一种具有良好应用前景的钠离子电池正极材料。采用溶胶-凝胶法和热处理的方式,制备Ca/Cu共掺杂的铁锰基层状氧化物(O3-Na_(0.9)Ca_(0.05)Fe_(0.45)Mn_(0.45)Cu_(0.1O)_(2))。采用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等对该O3型铁锰基层状氧化物正极材料进行表征分析。结果表明,在32 mA/g电流密度下该材料具有205.2 m A·h/g的高比容量,循环50圈之后仍具有67.64%的容量保持率,在160 m A/g下循环100圈后依然具有81.4 m A·h/g的放电比容量。由于Ca的掺入,引起Na^(+)空位的增加,并且Cu的掺入提高了Mn的价态,从而提高了Na^(+)的扩散速率,抑制了Mn3+的Jahn-Teller效应,缓解了晶格应力,有效提高了材料的结构稳定性和电化学性能。展开更多
The Co-free Li Ni_(0.5)Mn_(1.5)O_(4)(LNMO)is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs.However,the synthesis of LNMO is generally time and energy consuming,and its...The Co-free Li Ni_(0.5)Mn_(1.5)O_(4)(LNMO)is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs.However,the synthesis of LNMO is generally time and energy consuming,and its practical application is hindered by the lack of a compatible electrolyte.Herein,a spray pyrolysis-based energy-saving synthesis method as well as a diluted low concentration electrolyte(0.5 M LiPF_(6) in a mixture of fluoroethylene carbonate/dimethyl carbonate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(FEC:DMC:TTE,1:4:5 by volume))are proposed to address these challenges.Owing to the unique features of the precursor prepared by spray pyrolysis,well-crystallized LNMO single-crystal can be obtained within 1 h calcination at 900℃.Besides,the fluorinated interphases derived from the diluted low concentration electrolyte not only mitigate the Mn dissolution and Al corrosion at the cathode side,but also suppresses dendritic Li deposition at the anode side,thus enabling stable cycling of both LNMO and Li metal anode.Thus,30μm Li|LNMO(1.75 m A h cm^(-2))cells achieve a high capacity retention(90.9%)after 168 cycles in the diluted low concentration electrolyte.展开更多
Hafnium-based ferroelectric films,remaining their ferroelectricity down to nanoscale thickness,present a promising application for low-power logic devices and nonvolatile memories.It has been appealing for researchers...Hafnium-based ferroelectric films,remaining their ferroelectricity down to nanoscale thickness,present a promising application for low-power logic devices and nonvolatile memories.It has been appealing for researchers to reduce the required temperature to obtain the ferroelectric phase in hafnium-based ferroelectric films for applications such as flexible and wearable electronics.This work demonstrates that a remanent polarization(P_(r))value of>5μC/cm^(2)can be obtained in asdeposited Hf_(0.5)Zr_(0.5)O_(2)(HZO)films that are fabricated by thermal atomic layer deposition(TALD)under low temperature of 250℃.The ferroelectric orthorhombic phase(o-phase)in the as-deposited HZO films is detected by scanning transmission electron microscopy(STEM).This low fabrication temperature further extends the compatibility of ferroelectric HZO films to flexible electronics and avoids the cost imposed by following high-temperature annealing treatments.展开更多
In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)an...In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)and the Ag_(2)S content were optimized. The best 0.5% Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3)(KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag_(2)S. Under simulated sunlight, the NH_(3)generation rate of 0.5% Ag_(2)S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0.XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag_(2)S/KTN heterojunction established a type-Ⅱ band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag_(2)S/KTN composite exhibited higher NH3generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.展开更多
Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silic...Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.展开更多
Crystallization annealing is a crucial process for the formation of the ferroelectric phase in HfO_(2)-based ferroelectric thin films.Here,we systematically investigate the impact of the annealing process,with tempera...Crystallization annealing is a crucial process for the formation of the ferroelectric phase in HfO_(2)-based ferroelectric thin films.Here,we systematically investigate the impact of the annealing process,with temperature varied from 350℃to 550℃,on the electricity,ferroelectricity and reliability of a Hf_(0.5)Zr_(0.5)O_(2)(HZO;7.5 nm)film capacitor.It was found that HZO film annealed at a low temperature of 400℃can effectively suppress the formation of the monoclinic phase and reduce the leakage current.HZO film annealed at 400℃also exhibits better ferroelectric properties than those annealed at 350℃and 550℃.Specifically,the 400℃-annealed HZO film shows an outstanding 2Pr value of 54.6μC·cm^(-2)at±3.0 MV·cm^(-1),which is relatively high compared with previously reported values for HZO film under the same electric field and annealing temperature.When the applied electric field increases to±5.0 MV·cm^(-1),the 2Pr value can reach a maximum of 69.6μC·cm^(-2).In addition,the HZO films annealed at 400℃and 550℃can endure up to bout 2.3×10^(8)cycles under a cycling field of 2.0 MV·cm^(-1)before the occurrence of breakdown.In the 400℃-annealed HZO film,72.1%of the initial polarization is maintained while only 44.9%is maintained in the 550℃-annealed HZO film.Our work demonstrates that HZO film with a low crystallization temperature(400℃)has quite a high ferroelectric polarization,which is of significant importance in applications in ferroelectric memory and negative capacitance transistors.展开更多
Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode.In particular,the oxygen stoichio...Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode.In particular,the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in LNMO.The detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain challenging.In this study,the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively investigated.The high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface layer.The atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular brightfield techniques.For the synthesis of LNMO,the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in LNMO.The high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of LNMO.Therefore,the LNMO sintered at a medium temperature of 850°C achieved the best capacity retention.The results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO.展开更多
A C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG catalyst was synthesized using a one-step sol-gel method with silica gel(SG)as the carrier and C_(9)H_(10)O_(2):0.5ZnCl_(2)deep eutectic solvent(DES)as active component.The structure ...A C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG catalyst was synthesized using a one-step sol-gel method with silica gel(SG)as the carrier and C_(9)H_(10)O_(2):0.5ZnCl_(2)deep eutectic solvent(DES)as active component.The structure of the supported catalyst was characterized by FT-IR,XRD,SEM,and N2 adsorption-desorption,and the DES was found to have successfully permeated the SG through its pores.The removal of dibenzothiophene(DBT)in model diesel was studied using C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG as a catalyst and H_(2)O_(2)as an oxidant.The influence of loading dose of DES,reaction temperature,catalyst dosage,O/S molar ratio,and sulfide type on the desulfurization rate was investigated.The removal rates of DBT,4,6-dimethyldibenzothiophene(4,6-DMDBT),and benzothiophene(BT)under optimal reaction conditions were 99.4%,96%,and 78.2%,respectively.C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG catalyst could be recycled five times with a little decrease of oxidative desulfurization activity,and the adsorption-oxidation desulfurization mechanism was examined.展开更多
基金Project supported by the Fund from the Ministry of Science and Technology(MOST)of China(Grant No.2018YFE0202700)the National Natural Science Foundation of China(Grant Nos.11974422 and 12104504)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.22XNKJ30)。
文摘Hafnia-based ferroelectric materials, like Hf_(0.5)Zr_(0.5)O_(2)(HZO), have received tremendous attention owing to their potentials for building ultra-thin ferroelectric devices. The orthorhombic(O)-phase of HZO is ferroelectric but metastable in its bulk form under ambient conditions, which poses a considerable challenge to maintaining the operation performance of HZO-based ferroelectric devices. Here, we theoretically addressed this issue that provides parameter spaces for stabilizing the O-phase of HZO thin-films under various conditions. Three mechanisms were found to be capable of lowering the relative energy of the O-phase, namely, more significant surface-bulk portion of(111) surfaces, compressive c-axis strain,and positive electric fields. Considering these mechanisms, we plotted two ternary phase diagrams for HZO thin-films where the strain was applied along the in-plane uniaxial and biaxial, respectively. These diagrams indicate the O-phase could be stabilized by solely shrinking the film-thickness below 12.26 nm, ascribed to its lower surface energies. All these results shed considerable light on designing more robust and higher-performance ferroelectric devices.
文摘层状过渡金属氧化物由于其较高的理论比容量和较低的经济成本,被视为一种具有良好应用前景的钠离子电池正极材料。采用溶胶-凝胶法和热处理的方式,制备Ca/Cu共掺杂的铁锰基层状氧化物(O3-Na_(0.9)Ca_(0.05)Fe_(0.45)Mn_(0.45)Cu_(0.1O)_(2))。采用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等对该O3型铁锰基层状氧化物正极材料进行表征分析。结果表明,在32 mA/g电流密度下该材料具有205.2 m A·h/g的高比容量,循环50圈之后仍具有67.64%的容量保持率,在160 m A/g下循环100圈后依然具有81.4 m A·h/g的放电比容量。由于Ca的掺入,引起Na^(+)空位的增加,并且Cu的掺入提高了Mn的价态,从而提高了Na^(+)的扩散速率,抑制了Mn3+的Jahn-Teller效应,缓解了晶格应力,有效提高了材料的结构稳定性和电化学性能。
基金supported by the Fund of University of South China (No.201RGC013 and N0.200XQD052)。
文摘The Co-free Li Ni_(0.5)Mn_(1.5)O_(4)(LNMO)is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs.However,the synthesis of LNMO is generally time and energy consuming,and its practical application is hindered by the lack of a compatible electrolyte.Herein,a spray pyrolysis-based energy-saving synthesis method as well as a diluted low concentration electrolyte(0.5 M LiPF_(6) in a mixture of fluoroethylene carbonate/dimethyl carbonate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(FEC:DMC:TTE,1:4:5 by volume))are proposed to address these challenges.Owing to the unique features of the precursor prepared by spray pyrolysis,well-crystallized LNMO single-crystal can be obtained within 1 h calcination at 900℃.Besides,the fluorinated interphases derived from the diluted low concentration electrolyte not only mitigate the Mn dissolution and Al corrosion at the cathode side,but also suppresses dendritic Li deposition at the anode side,thus enabling stable cycling of both LNMO and Li metal anode.Thus,30μm Li|LNMO(1.75 m A h cm^(-2))cells achieve a high capacity retention(90.9%)after 168 cycles in the diluted low concentration electrolyte.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFA1200700)the National Natural Science Foundation of China(Grant Nos.T2222025 and 62174053)+5 种基金the Open Research Projects of Zhejiang Laboratory(Grant No.2021MD0AB03)the Shanghai Science and Technology Innovation Action Plan(Grant Nos.21JC1402000 and 21520714100)the Guangdong Provincial Key Laboratory Program(Grant No.2021B1212040001)the Fundamental Research Funds for the Central Universitiessupport from the Zuckerman STEM Leadership ProgramPazy Research Foundation(Grant No.149-2020)。
文摘Hafnium-based ferroelectric films,remaining their ferroelectricity down to nanoscale thickness,present a promising application for low-power logic devices and nonvolatile memories.It has been appealing for researchers to reduce the required temperature to obtain the ferroelectric phase in hafnium-based ferroelectric films for applications such as flexible and wearable electronics.This work demonstrates that a remanent polarization(P_(r))value of>5μC/cm^(2)can be obtained in asdeposited Hf_(0.5)Zr_(0.5)O_(2)(HZO)films that are fabricated by thermal atomic layer deposition(TALD)under low temperature of 250℃.The ferroelectric orthorhombic phase(o-phase)in the as-deposited HZO films is detected by scanning transmission electron microscopy(STEM).This low fabrication temperature further extends the compatibility of ferroelectric HZO films to flexible electronics and avoids the cost imposed by following high-temperature annealing treatments.
基金financially supported by National Natural Science Foundation of China (Grant No. 22172144)Nature Science Foundation of Zhejiang Province (Grant No. LY20B030004)。
文摘In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)and the Ag_(2)S content were optimized. The best 0.5% Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3)(KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag_(2)S. Under simulated sunlight, the NH_(3)generation rate of 0.5% Ag_(2)S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0.XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag_(2)S/KTN heterojunction established a type-Ⅱ band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag_(2)S/KTN composite exhibited higher NH3generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.
基金supported by the Fundamental Research Funds for the Central Universities(DUT21LK34)Natural Science Foundation of Liaoning Province(2020-MS-113).
文摘Rational design of oxygen evolution reaction(OER)catalysts at low cost would greatly benefit the economy.Taking advantage of earth-abundant elements Si,Co and Ni,we produce a unique-structure where cobalt-nickel silicate hydroxide[Co_(2.5)Ni_(0.5)Si_(2)O_(5)(OH)_(4)]is vertically grown on a reduced graphene oxide(rGO)support(CNS@rGO).This is developed as a low-cost and prospective OER catalyst.Compared to cobalt or nickel silicate hydroxide@rGO(CS@rGO and NS@rGO,respectively)nanoarrays,the bimetal CNS@rGO nanoarray exhibits impressive OER performance with an overpotential of 307 mV@10 mA cm^(-2).This value is higher than that of CS@rGO and NS@rGO.The CNS@rGO nanoarray has an overpotential of 446 mV@100 mA cm^(-2),about 1.4 times that of the commercial RuO_(2)electrocatalyst.The achieved OER activity is superior to the state-of-the-art metal oxides/hydroxides and their derivatives.The vertically grown nanostructure and optimized metal-support electronic interactions play an indispensable role for OER performance improvement,including a fast electron transfer pathway,short proton/electron diffusion distance,more active metal centers,as well as optimized dualatomic electron density.Taking advantage of interlay chemical regulation and the in-situ growth method,the advanced-structural CNS@rGO nanoarrays provide a new horizon to the rational and flexible design of efficient and promising OER electrocatalysts.
基金Hainan Provincial Natural Science Foundation of China(Grant No.523QN257)Collegelevel Scientific Research Foundation of Qiongtai Normal University(Grant No.qtqn202215)+6 种基金the Innovation and Entrepreneurship Training Program for College Students(Grant No.202213811016)Science and Technology Program of Henan(Grant No.232102210182)Scientific Research Foundation of Henan Normal University(Grant No.20230196)Natural Science Foundation of Shandong Province(Grant No.ZR2023QA047)Foundation of PeiXin(Grant No.2023PX027)Science and technology smes innovation ability improvement project(Grant No.2023TSGC0154)the National Natural Science Foundation of China(Grant No.62174059)。
文摘Crystallization annealing is a crucial process for the formation of the ferroelectric phase in HfO_(2)-based ferroelectric thin films.Here,we systematically investigate the impact of the annealing process,with temperature varied from 350℃to 550℃,on the electricity,ferroelectricity and reliability of a Hf_(0.5)Zr_(0.5)O_(2)(HZO;7.5 nm)film capacitor.It was found that HZO film annealed at a low temperature of 400℃can effectively suppress the formation of the monoclinic phase and reduce the leakage current.HZO film annealed at 400℃also exhibits better ferroelectric properties than those annealed at 350℃and 550℃.Specifically,the 400℃-annealed HZO film shows an outstanding 2Pr value of 54.6μC·cm^(-2)at±3.0 MV·cm^(-1),which is relatively high compared with previously reported values for HZO film under the same electric field and annealing temperature.When the applied electric field increases to±5.0 MV·cm^(-1),the 2Pr value can reach a maximum of 69.6μC·cm^(-2).In addition,the HZO films annealed at 400℃and 550℃can endure up to bout 2.3×10^(8)cycles under a cycling field of 2.0 MV·cm^(-1)before the occurrence of breakdown.In the 400℃-annealed HZO film,72.1%of the initial polarization is maintained while only 44.9%is maintained in the 550℃-annealed HZO film.Our work demonstrates that HZO film with a low crystallization temperature(400℃)has quite a high ferroelectric polarization,which is of significant importance in applications in ferroelectric memory and negative capacitance transistors.
基金National Natural Science Foundation of China,Grant/Award Numbers:22075003,22090043,U1930401,U2030206。
文摘Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode.In particular,the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in LNMO.The detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain challenging.In this study,the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively investigated.The high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface layer.The atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular brightfield techniques.For the synthesis of LNMO,the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in LNMO.The high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of LNMO.Therefore,the LNMO sintered at a medium temperature of 850°C achieved the best capacity retention.The results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO.
基金the financial support of the Natural Science Foundation of Liaoning Province(2019-ZD-0064)the Doctoral Fund of Liaoning Province(201501105).
文摘A C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG catalyst was synthesized using a one-step sol-gel method with silica gel(SG)as the carrier and C_(9)H_(10)O_(2):0.5ZnCl_(2)deep eutectic solvent(DES)as active component.The structure of the supported catalyst was characterized by FT-IR,XRD,SEM,and N2 adsorption-desorption,and the DES was found to have successfully permeated the SG through its pores.The removal of dibenzothiophene(DBT)in model diesel was studied using C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG as a catalyst and H_(2)O_(2)as an oxidant.The influence of loading dose of DES,reaction temperature,catalyst dosage,O/S molar ratio,and sulfide type on the desulfurization rate was investigated.The removal rates of DBT,4,6-dimethyldibenzothiophene(4,6-DMDBT),and benzothiophene(BT)under optimal reaction conditions were 99.4%,96%,and 78.2%,respectively.C_(9)H_(10)O_(2):0.5ZnCl_(2)/SG catalyst could be recycled five times with a little decrease of oxidative desulfurization activity,and the adsorption-oxidation desulfurization mechanism was examined.
