LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible cap...LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible capacity limits its replacement for LiCoO_(2) in high-end digital field.Herein,three-in-one modification,Na-doping and Al_(2)O_(3)@Li_(3)BO_(3) dual-coating simultaneously,is explored for single-crystalline LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(N-NCM@AB),which exhibits excellent high-voltage performance.N-NCM@AB displays a discharge-specific capacity of 201.8 mAh g^(−1) at 0.2 C with a high upper voltage of 4.6 V and maintains 158.9 mAh g^(−1) discharge capacity at 1 C over 200 cycles with the corresponding capacity retention of 87.8%.Remarkably,the N-NCM@AB||graphite pouch-type full cell retains 81.2% of its initial capacity with high working voltage of 4.4 V over 1600 cycles.More importantly,the fundamental understandings of three-in-one modification on surface morphology,crystal structure,and phase transformation of N-NCM@AB are clearly revealed.The Na+doped into the Li–O slab can enhance the bond energy,stabilize the crystal structure,and facilitate Li+transport.Additionally,the interior surface layer of Li^(+)-ions conductor Li_(3)BO_(3) relieves the charge transfer resistance with surface coating,whereas the outer surface Al_(2)O_(3) coating layer is beneficial for reducing the active materials loss and alleviating the electrode/electrolyte parasite reaction.This three-in-one strategy provides a reference for the further research on the performance attenuation mechanism of NCM,paving a new avenue to boost the high-voltage performance of NCM cathode in Li-ion batteries.展开更多
Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present...Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present for the first time that anomalous metastable hexagonal close-packed Ni nanoparticles induced by heteroatom N doping encapsulated in carbon(N-hcp-Ni/C) can exhibit admirable catalytic performance for ammonia borane(AB) dehydrogenation, prominently outperforming conventional fcc Ni counterpart with similar morphology and favorably presenting the state-of-the-art level.Comprehensive experimental and theoretical studies unravel that unusual hcp phase engineering of Ni together with N doping could induce charge redistribution and modulate electronic structure, thereby facilitating H_(2)O adsorption and expediting H_(2)O dissociation(rate-determining step). As a result, AB dehydrogenation can be substantially boosted with the assistance of N-hcp-Ni/C. Our proposed strategy highlights that unconventional crystal phase engineering coupled with non-metal heteroatom doping is a promising avenue to construct advanced transition metal catalysts for future renewable energy technologies.展开更多
In view of the special requirements of transducers for power ultrasonic processing,the piezoelectric ceramic material Pb(Zr,Ti)O3 was modified by adding other effective elements.The piezoelectric ceramic piece has a g...In view of the special requirements of transducers for power ultrasonic processing,the piezoelectric ceramic material Pb(Zr,Ti)O3 was modified by adding other effective elements.The piezoelectric ceramic piece has a good crystal phase structure,a stable piezoelectric constant,a higher dielectric constant,and a lower dielectric loss by adding a small amount of Sr^2+,Ba^2+,Ga^2+,Sn^4+,Nb^5+,etc.These properties are well suited to requirements of power ultrasonic transducer more than 1 000 W.The crystal phase structure and surface morphology of the modified piezoelectric ceramic chips were analyzed by X-ray and scanning electron microscopy (SEM) to prove that the piezoelectric ceramic chips have good crystal structure and density.The dielectric constant of the polarized piezoelectric ceramic chips was measured using an LCR meter.Finally,the piezoelectric ceramic chips were used to design the ultrasonic transducer,and the transducer was analyzed and measured by the impedance analyzer.The measurement results show that the performance of the piezoelectric ceramic chips is reasonable and feasible.展开更多
Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime go...Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.展开更多
In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the ...In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.展开更多
Ammonium aluminum carbonate hydroxide（AACH）, the precursor of α-Al2O3, was fabricated with NH4Al（SO4）2 and NH4HCO3 via a precipitation method. During the heat treatment AACH undergoes such a phase transformation ...Ammonium aluminum carbonate hydroxide（AACH）, the precursor of α-Al2O3, was fabricated with NH4Al（SO4）2 and NH4HCO3 via a precipitation method. During the heat treatment AACH undergoes such a phase transformation process: amorphous（350℃）→γ（700℃）→γ+θ（1050℃）→θ+α （1100℃）→α （1200℃）. Oxides, such as TiO2 sol and MgO sol were introduced into the precursor. Then both the α transformation temperature and the particle sizes of α-Al2O3 are decreased. The microstructures and its surface electronic properties of the powders are modified, and its dispersion property is improved. Doping TiO2 sol grains, AACH completes α phase transformation nearly at 1100℃, its first-order diameter is about 120nm. Doping with MgO sol grains, α phase transformation completes after being sintered at 1100℃.展开更多
As the primary suppliers of cyclable sodium ions,O3-type layer-structured manganese-based oxides are recognized as highly competitive cathode candidates for sodium-ion batteries.To advance the development of high-ener...As the primary suppliers of cyclable sodium ions,O3-type layer-structured manganese-based oxides are recognized as highly competitive cathode candidates for sodium-ion batteries.To advance the development of high-energy sodium-ion batteries,it is crucial to explore cathode materials operating at high voltages while maintaining a stable cycling behavior.The orbital and electronic structure of the octahedral center metal element plays a crucial role in maintaining the octahedra structural integrity and improving Na^(+)ion diffusion by introducing heterogeneous chemical bonding.Inspired by the abundant configuration of extra nuclear electrons and large ion radius,we employed trace amounts of tungsten in this study.The obtained cathode material can promote the reversibility of oxygen redox reactions in the high-voltage region and inhibit the loss of lattice oxygen.Additionally,the formation of a Na_(2)WO_(4) coating on the material surface can improve the interfacial stability and interface ions diffusion.It demonstrates an initial Coulombic efficiency(ICE)of 94.6%along with 168.5 mA h g^(-1 )discharge capacity within the voltage range of 1.9-4.35 V.These findings contribute to the advancement of high-energy sodium-ion batteries by providing insights into the benefits of tungsten doping and Na_(2)WO_(4) coating on cathode materials.展开更多
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(52070194,51902347,51908555,and 51822812)Natural Science Foundation of Hunan Province(2020JJ5741)the Graduate Innovation Project of Central South University(2020zzts093).
文摘LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) is extensively researched as one of the most widely used commercially materials for Li-ion batteries at present.However,the poor high-voltage performance(≥4.3 V)with low reversible capacity limits its replacement for LiCoO_(2) in high-end digital field.Herein,three-in-one modification,Na-doping and Al_(2)O_(3)@Li_(3)BO_(3) dual-coating simultaneously,is explored for single-crystalline LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(N-NCM@AB),which exhibits excellent high-voltage performance.N-NCM@AB displays a discharge-specific capacity of 201.8 mAh g^(−1) at 0.2 C with a high upper voltage of 4.6 V and maintains 158.9 mAh g^(−1) discharge capacity at 1 C over 200 cycles with the corresponding capacity retention of 87.8%.Remarkably,the N-NCM@AB||graphite pouch-type full cell retains 81.2% of its initial capacity with high working voltage of 4.4 V over 1600 cycles.More importantly,the fundamental understandings of three-in-one modification on surface morphology,crystal structure,and phase transformation of N-NCM@AB are clearly revealed.The Na+doped into the Li–O slab can enhance the bond energy,stabilize the crystal structure,and facilitate Li+transport.Additionally,the interior surface layer of Li^(+)-ions conductor Li_(3)BO_(3) relieves the charge transfer resistance with surface coating,whereas the outer surface Al_(2)O_(3) coating layer is beneficial for reducing the active materials loss and alleviating the electrode/electrolyte parasite reaction.This three-in-one strategy provides a reference for the further research on the performance attenuation mechanism of NCM,paving a new avenue to boost the high-voltage performance of NCM cathode in Li-ion batteries.
基金supported by the National Natural Science Foundation of China (52002412 and 22072186)the Natural Science Foundation of Guangdong Province (2021A1515010575)the Guangzhou Science and Technology Plan General Project (202102020862)。
文摘Developing high-performing non-noble transition metal catalysts for H_(2) evolution from chemical hydrogen storage materials is of great significance for the hydrogen economy system, yet challenging. Herein,we present for the first time that anomalous metastable hexagonal close-packed Ni nanoparticles induced by heteroatom N doping encapsulated in carbon(N-hcp-Ni/C) can exhibit admirable catalytic performance for ammonia borane(AB) dehydrogenation, prominently outperforming conventional fcc Ni counterpart with similar morphology and favorably presenting the state-of-the-art level.Comprehensive experimental and theoretical studies unravel that unusual hcp phase engineering of Ni together with N doping could induce charge redistribution and modulate electronic structure, thereby facilitating H_(2)O adsorption and expediting H_(2)O dissociation(rate-determining step). As a result, AB dehydrogenation can be substantially boosted with the assistance of N-hcp-Ni/C. Our proposed strategy highlights that unconventional crystal phase engineering coupled with non-metal heteroatom doping is a promising avenue to construct advanced transition metal catalysts for future renewable energy technologies.
基金Funded by the National Natural Science Foundation of China(51975540)the Youth Science and Technology Research Fundation of Shanxi Province of China(201901D211204)。
文摘In view of the special requirements of transducers for power ultrasonic processing,the piezoelectric ceramic material Pb(Zr,Ti)O3 was modified by adding other effective elements.The piezoelectric ceramic piece has a good crystal phase structure,a stable piezoelectric constant,a higher dielectric constant,and a lower dielectric loss by adding a small amount of Sr^2+,Ba^2+,Ga^2+,Sn^4+,Nb^5+,etc.These properties are well suited to requirements of power ultrasonic transducer more than 1 000 W.The crystal phase structure and surface morphology of the modified piezoelectric ceramic chips were analyzed by X-ray and scanning electron microscopy (SEM) to prove that the piezoelectric ceramic chips have good crystal structure and density.The dielectric constant of the polarized piezoelectric ceramic chips was measured using an LCR meter.Finally,the piezoelectric ceramic chips were used to design the ultrasonic transducer,and the transducer was analyzed and measured by the impedance analyzer.The measurement results show that the performance of the piezoelectric ceramic chips is reasonable and feasible.
基金supported by the National Natural Science Foundation of China(U1663225,21805280 and 21805220)the Youth Innovation Foundation of Xiamen City:3502Z20206085+4 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R52)The Opening Project of PCOSS,Xiamen University,201907the program of introducing Talents of discipline to Universities-111 Project(Grant No.B20002)the project“Depollut Air”of Interreg V France-Wallonie-Vlaanderenthe financial support from the China Scholarship Council(CSC)。
文摘Photocatalytic (PC) / Photoelectrochemical (PEC) water splitting under solar light irradiation is considered as a prospective technique to support the sustainable and renewable H_(2) economy and to reach the ultime goal of carbon neutral. TiO_(2) based photocatalysts with high chemical stability and excellent photocatalytic properties have great potential for solar-to-H_(2) conversion. To conquer the challenges of the large band-gap and rapid recombination of photo generated electron-holepairs in TiO_(2), non-metal doping turns out to be economic, facile, and effective on boosting the visible light activity. The localized defect states such as oxygen vacancy and Ti^(3+) generated by non-metal doping are located in the band-gap of TiO_(2), which result in the reduction of band-gap, thus a red-shift of the absorption edge. The hetero doping atoms such as B^(3+), I^(7+), S^(4+)/S^(6+), P^(5+) can also act as electron donors or trap sites which facilitate the charge carrier separation and suppress the recombination of electron-hole pairs. In this comprehensive review, we present the most recent advances on non-metal doped TiO_(2) photocatalysts in terms of fundamental aspects, origin of visible light activity and the PC / PEC behaviours for water splitting. In particular, the characteristics of different non-metal elements (N, C, B, S, P, Halogens) as dopants are discussed in details focusing on the synthesis approaches, characterization as well as the efficiency of PC and PEC water splitting. The present review aims at guiding the readers who want quick access to helpful information about how to efficiently improve the performance of photocatalysts by simple doping strategies and could stimulate new intuitive into the new doping strategies.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51072012 and 51272015)
文摘In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.
文摘Ammonium aluminum carbonate hydroxide（AACH）, the precursor of α-Al2O3, was fabricated with NH4Al（SO4）2 and NH4HCO3 via a precipitation method. During the heat treatment AACH undergoes such a phase transformation process: amorphous（350℃）→γ（700℃）→γ+θ（1050℃）→θ+α （1100℃）→α （1200℃）. Oxides, such as TiO2 sol and MgO sol were introduced into the precursor. Then both the α transformation temperature and the particle sizes of α-Al2O3 are decreased. The microstructures and its surface electronic properties of the powders are modified, and its dispersion property is improved. Doping TiO2 sol grains, AACH completes α phase transformation nearly at 1100℃, its first-order diameter is about 120nm. Doping with MgO sol grains, α phase transformation completes after being sintered at 1100℃.
基金supported by the National Natural Science Foundation of China(Grant No.52272194)LiaoNing Revitalization Talents Program(Grant No.XLYC2007155)。
文摘As the primary suppliers of cyclable sodium ions,O3-type layer-structured manganese-based oxides are recognized as highly competitive cathode candidates for sodium-ion batteries.To advance the development of high-energy sodium-ion batteries,it is crucial to explore cathode materials operating at high voltages while maintaining a stable cycling behavior.The orbital and electronic structure of the octahedral center metal element plays a crucial role in maintaining the octahedra structural integrity and improving Na^(+)ion diffusion by introducing heterogeneous chemical bonding.Inspired by the abundant configuration of extra nuclear electrons and large ion radius,we employed trace amounts of tungsten in this study.The obtained cathode material can promote the reversibility of oxygen redox reactions in the high-voltage region and inhibit the loss of lattice oxygen.Additionally,the formation of a Na_(2)WO_(4) coating on the material surface can improve the interfacial stability and interface ions diffusion.It demonstrates an initial Coulombic efficiency(ICE)of 94.6%along with 168.5 mA h g^(-1 )discharge capacity within the voltage range of 1.9-4.35 V.These findings contribute to the advancement of high-energy sodium-ion batteries by providing insights into the benefits of tungsten doping and Na_(2)WO_(4) coating on cathode materials.
