Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explo...Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x and TiO2_xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HC104. Pt/TiO2_x and Pt/TiO2_xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiOE_x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.展开更多
Lithium-sulfur(Li-S)batteries are promising for high-energy-density storage,but their performance is limited by sluggish lithium polysulfide(LiPS)conversion kinetics.Here,we tackle this issue by synthesizing ultrafine...Lithium-sulfur(Li-S)batteries are promising for high-energy-density storage,but their performance is limited by sluggish lithium polysulfide(LiPS)conversion kinetics.Here,we tackle this issue by synthesizing ultrafine truncated octahedral TiO_(2) nanocrystals(P-O_(v)-TiO_(2)),featuring specific{101}facets and dual defects—phosphorus doping and oxygen vacancies.Acting as an efficient electrocatalyst in the separator,P-O_(v)-TiO_(2) exhibits superior catalytic properties,where oxygen vacancies modulate the electronic structure,enhancing electron enrichment and charge transfer;phosphorus doping tailors the d-band center of the catalyst,strengthening Ti-S interactions between the{101}facets and LiPSs.As a result,Li-S coin cells modified with P-O_(v)-TiO_(2) achieve a high specific capacity of 895 mAh g^(−1) at 5 C and exhibit a minimal decay rate of 0.14%per cycle over 200 cycles.Furthermore,Li-S pouch cells deliver a high capacity of 1004 mAh g^(−1) at 0.1 C under lean electrolyte conditions.This study elucidates the mechanisms of charge states on specific crystal planes and deepens our understanding of dual-defect engineering in Li-S electrochemistry,offering a promising approach for developing efficient and cost-effective catalysts for Li-S battery applications.展开更多
Advancing clean energy technologies demands efficient and durable electrode catalysts for solid oxide cells(SOCs).Despite their exceptional catalytic properties,Pt-based materials face critical challenges in high-temp...Advancing clean energy technologies demands efficient and durable electrode catalysts for solid oxide cells(SOCs).Despite their exceptional catalytic properties,Pt-based materials face critical challenges in high-temperature applications owing to particle agglomeration and cost constraints.Here,we demonstrate a rational design strategy utilizing controlled in situ exsolution to create strongly anchored PtSn nanoalloys on oxygen-deficient PrBaMn_(1.8)Pt_(0.1)Sn_(0.1)O_(5+δ)(L-PBMPtSn)perovskite oxide.Through precise compositional engineering and structural control,we achieved a uniform dispersion of PtSn nanoparticles with unique socket-like interfaces that prevent agglomeration while maintaining high catalytic accessibility.The optimized electrode demonstrates remarkable bifunctional performance,achieving a current density of 1.6 A cm^(-2)at 1.8 V for CO_(2)electrolysis and a maximum power density of 316 mW cm^(-2)for fuel cell operation at 800℃.More significantly,the electrode exhibits exceptional stability with only 9.6%performance degradation over 100 h of operation,which is a substantial improvement over conventional electrodes.Our findings establish a new paradigm for designing high-performance SOC electrodes through the controlled exsolution of precious metal alloys,offering broader implications for catalyst design in high-temperature electrochemical systems.展开更多
This paper investigates the excited states of Si3O molecule by using the single-excitation configuration interaction and density functional theory. It finds that the visible light absorption spectrum of Si3O molecule ...This paper investigates the excited states of Si3O molecule by using the single-excitation configuration interaction and density functional theory. It finds that the visible light absorption spectrum of Si3O molecule comprises the yellow and the purple light without external electric field, however all the visible light is included except the green light under the action of external electric field. Oxygen-deficient defects, which also can be found in Si3O molecule, have been used to explain the 1 from silicon-based materials but the microstructures of the materials are still uncertain Our results accord with the experimental values perfectly, this fact suggests that the structure of Si3O molecule is expected to be one of the main basic structures of the materials, so the oxygen-deficient defect structural model for Si3O molecule also has been provided to research the structures of materials.展开更多
Oxygen-deficient LiV_(3)O_(8)is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and...Oxygen-deficient LiV_(3)O_(8)is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and study the content and position of V^(4+)and oxygen vacancies in LiV_(3)O_(8),and therefore the mechanism of improving electrochemical performance of LiV_(3)O_(8)is still unclear.Herein,we developed four LiV_(3)O_(8)nanosheets with different V^(4+)and oxygen vacancy contents and positions.The physicochemical and lithium storage properties indicate that the V^(4+)and oxygen vacancies in the surface layer increase the contribution of pseudocapacitive lithium storage on the nanosheet surface.The V^(4+)and oxygen vacancies in the lattice improve the electrical conductivity of LiV_(3)O_(8),and enhance the phase transformation and lithium ion diffusion rates.By adjusting the content of V^(4+)and oxygen vacancies,we obtained an oxygen-deficient LiV_(3)O_(8)nanosheet which maintained more than 93%of the initial reversible capacity after 300 cycles at 5,000 mA·g^(−1).The V^(4+)and oxygen vacancies play an important role in improving the stability and rapidity of lithium storage.This work is helpful to understand the stable and fast lithium storage mechanism of oxygen-deficient LiV_(3)O_(8),and might lay a foundation for further studies of other oxygen-deficient metal oxide electrodes for long-life and high-power LIBs.展开更多
The structure of the Si3Ox （x =2, 3） cluster is investigated; we find that the geometry of Si3O2 is similar to that of Si3O3 except for the oxygen-deficient defect structure （Si-Si band） which exists only in the S...The structure of the Si3Ox （x =2, 3） cluster is investigated; we find that the geometry of Si3O2 is similar to that of Si3O3 except for the oxygen-deficient defect structure （Si-Si band） which exists only in the Si3O2 cluster. It is known that oxygen-deficient defects are used to explain visible luminescence （especially blue, purple and ultraviolet light） from silicon-based materials, which are directly bound up with the excited states of the molecules. Therefore the excitation properties of the two clusters are also studied. Our results show that the absorption spectrum of Si3O2 is concentrated in the visible light region. In contrast, the absorption spectrum of Si3O3 is mainly located in the ultraviolet light region. The calculations are perfectly consistent with experimental data and also support the theory of oxygen-deficient defects.展开更多
Lithium-rich manganese-based oxides(LRMOs)have been considered as one of the most promising cathode materials owing to their superior specific capacity and high operating voltage.However,their largescale commercial ap...Lithium-rich manganese-based oxides(LRMOs)have been considered as one of the most promising cathode materials owing to their superior specific capacity and high operating voltage.However,their largescale commercial applications are limited due to problems such as structural instability,voltage decay,and poor cycle stability.Herein,pre-generated oxygen vacancies and oxygen-deficient phase were introduced to Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)(LMNO)using a facile urea-assisted mixed gas treatment(UMGT)method for facilitating electronic and ionic conductivity,reducing the surface oxygen partial pressure,and suppressing the release of lattice oxygen.Compared with the pristine LMNO material,the UMGT sample modified at 200℃exhibited enhanced discharge capacity,capacity retention,and rate capability.In addition,the Li+diffusion coefficient significantly improved by 50%than that of the reference LMNO.More importantly,the voltage decay was effectively suppressed,with average potential decreasing from 0.53 V(LMNO)to 0.39 V(UMGT-200)after 200 cycles at 1 C.The proposed UMGT method provides an effective strategy to alleviate the phase transition and improve the electrochemical performance for lithium-rich materials,and identifies a promising research direction to inhibit the voltage decay of layered anion redox cathode materials.展开更多
Highly efficient,environmentally friendly,and inexpensive cathode materials have been regarded as the core elements in a wide range of rechargeable alkaline zinc batteries(RAZBs).Herein,a three-dimensional ordered mes...Highly efficient,environmentally friendly,and inexpensive cathode materials have been regarded as the core elements in a wide range of rechargeable alkaline zinc batteries(RAZBs).Herein,a three-dimensional ordered mesoporous nitrogen-doped oxygen-deficient iron trioxide nanoarray(denoted as N-Fe_(2)O_(3)−x)has been developed as a new kind of cathode material for RAZBs,with great promise.The N-Fe_(2)O_(3)−x nanoarray is prepared via a unique high-isostatic pressure-assisted nanocasting process and N_(2) plasma activation,which endow the N-Fe_(2)O_(3)−x material with highly effective areas,abundant active sites,fast electrolyte diffusion channels,and shortened charge transport pathways.Consequently,a high capacity of 288 mA h g^(−1)(at 1.0 A g^(−1))and an excellent energy density of 135 W h kg^(−1)(based on the weights of N-Fe_(2)O_(3)−x)are achieved for the Zn battery composed of N-Fe_(2)O_(3)−x//Zn by using the optimized N-Fe_(2)O_(3)−x material as the cathode and Zn metal as the anode.Moreover,the rechargeable Zn battery possesses excellent stability;at 10 A g^(−1),the battery retains 73%capacitance after 1000 cycles.The excellent electrochemical performance of the N-Fe_(2)O_(3)−x//Zn battery is much higher than those of the current Zn batteries based on iron oxides and hydroxides.This is the first example of using iron trioxide as a cathode for RAZBs,which may be of intense interest to later researchers.展开更多
Natural magnetite formed by the isomorphism substitutions of transition metals,including Fe,Ti,Co,etc.,was activated by mechanical grinding followed by H2 reduction.The temperature-programmed reduction of hydrogen(H2-...Natural magnetite formed by the isomorphism substitutions of transition metals,including Fe,Ti,Co,etc.,was activated by mechanical grinding followed by H2 reduction.The temperature-programmed reduction of hydrogen(H2-TPR)and temperature-programmed surface reaction of carbon dioxide(CO_(2)-TPSR)were carried out to investigate the processes of oxygen loss and CO_(2)reduction.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),and energy-dispersive X-ray spectroscopy(EDS).The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H2 atmosphere.Meanwhile,the activity and selectivity of CO_(2)reduction into carbon were enhanced.The deposited carbon on the activated natural magnetite was confirmed as amorphous.The amount of carbon after CO_(2)reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt%higher than that over the natural magnetite.展开更多
In recent years, considerable progresses have been made in studies on diverseutilizations of carbon dioxide. For carbon dioxide, there are two problems worthy of con-cern: one is the ’greenhouse effect’ caused by ca...In recent years, considerable progresses have been made in studies on diverseutilizations of carbon dioxide. For carbon dioxide, there are two problems worthy of con-cern: one is the ’greenhouse effect’ caused by carbon dioxide on the earth, the other is展开更多
Lithium-ion capacitor (LIC) has been regarded as a promising energy storage system with high powder density and high energy density.However,the kinetic mismatch between the anode and the cathode is a major issue to be...Lithium-ion capacitor (LIC) has been regarded as a promising energy storage system with high powder density and high energy density.However,the kinetic mismatch between the anode and the cathode is a major issue to be solved.Here we report a high-performance asymmetric LIC based on oxygen-deficient black-TiO2-x/graphene (B-TiO2-x/G) aerogel anode and biomass derived microporous carbon cathode.Through a facile one-pot hydrothermal process,graphene nanosheets and oxygen-vacancy-rich porous B-TiO2-x/G nanosheets were self-assembled into three-dimensional (3D) interconnected B-TiO2-x/G aerogel.Owing to the rich active sites,high conductivity and fast kinetics,the B-TiO2-x/G aerogel exhibits remarkable reversible capacity,high rate capability and long cycle life when used as anode material for lithium ion storage.Moreover,density functional theory (DFT) calculation reveals that the incorporation of graphene nanosheets can reduce the energy barrier of Li^+ diffusion in B-TiO2-x.The asymmetric LIC based on B-TiO2-x/G aerogel anode and naturally-abundant pine-needles derived microporous carbon (MPC) cathode work well within a large voltage window (1.0-4.0 V),and can deliver high energy density (166.4 Wh·kg^-1 at 200 mA·g^-1),and high power density (7.9 kW·kg^-1 at 17.1 Wh·kg^-1).Moreover,the LIC shows a high capacitance retention of 87% after 3,000cycles at 2,000 mA·g^-1.The outstanding electrochemical performances indicate that the rationally-designed LICs have promising prospect to serve as advanced fast-charging energy storage devices.展开更多
Artificial Z-scheme photocatalytic systems have received considerable attention in recent years because they can achieve wide light-absorption, high charge-separation efficiency, and strong redox ability simultaneousl...Artificial Z-scheme photocatalytic systems have received considerable attention in recent years because they can achieve wide light-absorption, high charge-separation efficiency, and strong redox ability simultaneously. Nevertheless, it is still challenging to exploit low-cost and stable Zscheme photocatalysts with highly-efficient H2 evolution from solar water-splitting so far. Herein, we report a novel all-solidstate Z-scheme photocatalyst Cd1-xZnxS@WO3-x consisting of Cd1-xZnxS nanorods coated with oxygen-deficient WO3-x amorphous layers. The Cd1-xZnxS@WO3-x exhibits an outstanding H2 evolution reaction(HER) activity as compared with Pt-loaded Cd1-xZnxS and most WO3- and Cd S-based photocatalysts, due to the generation of stronger reducing electrons through the appropriate Zn-doping in Cd1-xZnxS and the enhanced charge transfer by introducing oxygen vacancies(W^5+/OVs) into the ultrathin WO3-x amorphous coatings. The optimal HER rate of Cd1-xZnxS@WO3- xis determined to be 21.68 mmol h^-1 g^-1, which is further raised up to 28.25 mmol h^-1 g^-1(about 12 times more than that of Pt/Cd1-xZnxS) when Cd1-xZnxS@WO3-x is hybridized by Co Ox and Ni Oxdual cocatalysts(Cd1-xZnxS@WO3-x/CoOx/NiOx)through in-situ photo-deposition. Moreover, the corresponding apparent quantum yield(AQY) at 420 nm is significantly increased from 34.6% for Cd1-xZnxS@WO3-x to 60.8% for Cd1-xZnxS@WO3-x/CoOx/NiOx. In addition, both Cd1-xZnxS@WO3-x and Cd1-xZnxS@WO3-x/CoOx/NiOx demonstrate good stability towards HER. The results displayed in this work will inspire the rational design and synthesis of high-performance nanostructures for photocatalytic applications.展开更多
The La2/3Cal/3Mn03_σ film has been deposited on the （001） SrTiO3 substrate and its temper- ature-dependent photoconductive properties have been investigated from 80 to 300 K. The La2/3Cal/3MnO3-σ film has a novel ...The La2/3Cal/3Mn03_σ film has been deposited on the （001） SrTiO3 substrate and its temper- ature-dependent photoconductive properties have been investigated from 80 to 300 K. The La2/3Cal/3MnO3-σ film has a novel photoelectric property due to its oxygen-deficient structure. We observed laser-induced giant negative photoresistance of the sample in a wide temperature range. The change rate of negative photoresistance was nearly 100% at the low temperature when the sample was irradiated by 532 nm laser. In addition, this effect was sensitive to the power of laser irradiation. The oxygen-deficiency of La2/3Cal/3Mn03-σ film seems to have an impact on the laser-induced resistance variation. The experimental results made the La2/3Cal/3MnO3_σ film a promising application as a photoswitch device.展开更多
基金the China Scholarship Council for a research grant
文摘Insufficient electrochemical stability is a major challenge for carbon materials in oxygen reduction reaction （ORR） due to carbon corrosion and insufficient metal-support interactions. In this work, titania is explored as an alternative support for Pt catalysts. Oxygen deficient titania samples including TiO2-x and TiO2_xNy were obtained by thermal treatment of anatase TiO2 under flowing H2 and NH3, respectively. Pt nanoparticles were deposited on the titania by a modified ethylene glycol method. The samples were characterized by N2-physisorption, X-ray diffraction and X-ray photoelectron spectroscopy. The ORR activity and long-term stability of supported Pt catalysts were evaluated using linear sweep voltammetry and chronoamperometry in 0.1 mol/L HC104. Pt/TiO2_x and Pt/TiO2_xNy showed higher ORR activities than Pt/TiO2 as indicated by higher onset potentials. Oxygen deficiency in TiO2-x and TiO2-xNy contributed to the high ORR activity due to enhanced charge transfer, as disclosed by electrochemical impedance spectroscopy studies. Electrochemical stability studies revealed that Pt/TiOE_x exhibited a higher stability with a lower current decay rate than commercial Pt/C, which can be attributed to the stable oxide support and strong interaction between Pt nanoparticles and the oxygen-deficient TiO2-x support.
基金supported by the Hebei Province Key R&D Technology Project(23314401D)2023 Hebei Province High-level Talent Team Construction Special Project(235A4401D)+6 种基金Hebei North University Youth Fund Project(XJ2024013)School-level Cultivation Research Project of Hebei North University(XJPY2024025)First Batch of School-level Scientific Research Projects of Hebei North University in 2023(B2023405004)Hebei North University High-level Talent Research Start-up Fund(BSJJ202303,BSJJ202313,BSJJ202421)Science and Technology Research Project of Higher Education Institutions in Hebei Province(QN2023222)Central Guided Local Science and Technology Development Funding Program(236Z4401G)Natural Science Foundation of Hebei Province(B2022405005).
文摘Lithium-sulfur(Li-S)batteries are promising for high-energy-density storage,but their performance is limited by sluggish lithium polysulfide(LiPS)conversion kinetics.Here,we tackle this issue by synthesizing ultrafine truncated octahedral TiO_(2) nanocrystals(P-O_(v)-TiO_(2)),featuring specific{101}facets and dual defects—phosphorus doping and oxygen vacancies.Acting as an efficient electrocatalyst in the separator,P-O_(v)-TiO_(2) exhibits superior catalytic properties,where oxygen vacancies modulate the electronic structure,enhancing electron enrichment and charge transfer;phosphorus doping tailors the d-band center of the catalyst,strengthening Ti-S interactions between the{101}facets and LiPSs.As a result,Li-S coin cells modified with P-O_(v)-TiO_(2) achieve a high specific capacity of 895 mAh g^(−1) at 5 C and exhibit a minimal decay rate of 0.14%per cycle over 200 cycles.Furthermore,Li-S pouch cells deliver a high capacity of 1004 mAh g^(−1) at 0.1 C under lean electrolyte conditions.This study elucidates the mechanisms of charge states on specific crystal planes and deepens our understanding of dual-defect engineering in Li-S electrochemistry,offering a promising approach for developing efficient and cost-effective catalysts for Li-S battery applications.
基金supported by the National Natural Science Foundation of China(Nos.22272081 and 52473235)Postgraduate Research and Practice Innovation Program of Jiangsu Province(No.KYCX24_1527)National Research Foundation of Korea(NRF)grant funded by the Korea governement(MSIT)(No.RS-2024-00347253)
文摘Advancing clean energy technologies demands efficient and durable electrode catalysts for solid oxide cells(SOCs).Despite their exceptional catalytic properties,Pt-based materials face critical challenges in high-temperature applications owing to particle agglomeration and cost constraints.Here,we demonstrate a rational design strategy utilizing controlled in situ exsolution to create strongly anchored PtSn nanoalloys on oxygen-deficient PrBaMn_(1.8)Pt_(0.1)Sn_(0.1)O_(5+δ)(L-PBMPtSn)perovskite oxide.Through precise compositional engineering and structural control,we achieved a uniform dispersion of PtSn nanoparticles with unique socket-like interfaces that prevent agglomeration while maintaining high catalytic accessibility.The optimized electrode demonstrates remarkable bifunctional performance,achieving a current density of 1.6 A cm^(-2)at 1.8 V for CO_(2)electrolysis and a maximum power density of 316 mW cm^(-2)for fuel cell operation at 800℃.More significantly,the electrode exhibits exceptional stability with only 9.6%performance degradation over 100 h of operation,which is a substantial improvement over conventional electrodes.Our findings establish a new paradigm for designing high-performance SOC electrodes through the controlled exsolution of precious metal alloys,offering broader implications for catalyst design in high-temperature electrochemical systems.
基金Project supported by the Foundation for University Young Core Instructors of Henan Province,China(Grant No.2009GGJS-044)the Natural Science Foundation of the Education Bureau of Henan Province,China(Grant No.2010A140008)+1 种基金the Natural Science Foundation of Henan Province,China(Grant No.092300410249)the Natural Science Foundation of the Education Bureau of Henan Province,China(Grant No.2010A140008)
文摘This paper investigates the excited states of Si3O molecule by using the single-excitation configuration interaction and density functional theory. It finds that the visible light absorption spectrum of Si3O molecule comprises the yellow and the purple light without external electric field, however all the visible light is included except the green light under the action of external electric field. Oxygen-deficient defects, which also can be found in Si3O molecule, have been used to explain the 1 from silicon-based materials but the microstructures of the materials are still uncertain Our results accord with the experimental values perfectly, this fact suggests that the structure of Si3O molecule is expected to be one of the main basic structures of the materials, so the oxygen-deficient defect structural model for Si3O molecule also has been provided to research the structures of materials.
基金the financial support of Beijing Natural Science Foundation(No.2182015)the National Natural Science Foundation of China(No.21805012).
文摘Oxygen-deficient LiV_(3)O_(8)is considered as one of the promising cathode materials for lithium ion batteries(LIBs)because of its high cycling stability and rate capability.However,it is very difficult to control and study the content and position of V^(4+)and oxygen vacancies in LiV_(3)O_(8),and therefore the mechanism of improving electrochemical performance of LiV_(3)O_(8)is still unclear.Herein,we developed four LiV_(3)O_(8)nanosheets with different V^(4+)and oxygen vacancy contents and positions.The physicochemical and lithium storage properties indicate that the V^(4+)and oxygen vacancies in the surface layer increase the contribution of pseudocapacitive lithium storage on the nanosheet surface.The V^(4+)and oxygen vacancies in the lattice improve the electrical conductivity of LiV_(3)O_(8),and enhance the phase transformation and lithium ion diffusion rates.By adjusting the content of V^(4+)and oxygen vacancies,we obtained an oxygen-deficient LiV_(3)O_(8)nanosheet which maintained more than 93%of the initial reversible capacity after 300 cycles at 5,000 mA·g^(−1).The V^(4+)and oxygen vacancies play an important role in improving the stability and rapidity of lithium storage.This work is helpful to understand the stable and fast lithium storage mechanism of oxygen-deficient LiV_(3)O_(8),and might lay a foundation for further studies of other oxygen-deficient metal oxide electrodes for long-life and high-power LIBs.
基金supported by the Natural Science Foundation of Henan Province of China (Grant No. 092300410249)the Natural Science Foundation of the Education Bureau of Henan Province of China (Grant No. 2010A140008)the Foundation for University Young Core Instructors of Henan Province, China (Grant No. 2009GGJS-044)
文摘The structure of the Si3Ox （x =2, 3） cluster is investigated; we find that the geometry of Si3O2 is similar to that of Si3O3 except for the oxygen-deficient defect structure （Si-Si band） which exists only in the Si3O2 cluster. It is known that oxygen-deficient defects are used to explain visible luminescence （especially blue, purple and ultraviolet light） from silicon-based materials, which are directly bound up with the excited states of the molecules. Therefore the excitation properties of the two clusters are also studied. Our results show that the absorption spectrum of Si3O2 is concentrated in the visible light region. In contrast, the absorption spectrum of Si3O3 is mainly located in the ultraviolet light region. The calculations are perfectly consistent with experimental data and also support the theory of oxygen-deficient defects.
基金supported by the National Natural Science Foundation of China(51802019,51802020)the Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxm X0589,cstc2020jcyj-msxm X0654)+2 种基金the Science and Technology Innovation Foundation of Beijing Institute of Technology Chongqing Innovation Center(2020CX5100006)the Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)the support from Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Lithium-rich manganese-based oxides(LRMOs)have been considered as one of the most promising cathode materials owing to their superior specific capacity and high operating voltage.However,their largescale commercial applications are limited due to problems such as structural instability,voltage decay,and poor cycle stability.Herein,pre-generated oxygen vacancies and oxygen-deficient phase were introduced to Li_(1.2)Mn_(0.6)Ni_(0.2)O_(2)(LMNO)using a facile urea-assisted mixed gas treatment(UMGT)method for facilitating electronic and ionic conductivity,reducing the surface oxygen partial pressure,and suppressing the release of lattice oxygen.Compared with the pristine LMNO material,the UMGT sample modified at 200℃exhibited enhanced discharge capacity,capacity retention,and rate capability.In addition,the Li+diffusion coefficient significantly improved by 50%than that of the reference LMNO.More importantly,the voltage decay was effectively suppressed,with average potential decreasing from 0.53 V(LMNO)to 0.39 V(UMGT-200)after 200 cycles at 1 C.The proposed UMGT method provides an effective strategy to alleviate the phase transition and improve the electrochemical performance for lithium-rich materials,and identifies a promising research direction to inhibit the voltage decay of layered anion redox cathode materials.
基金supported by the National Natural Science Foundation for Young Scientists of China(21805316)the Natural Science Foundation of Hubei Province(2020CFB430)Hubei Provincial Department of Education(Q20192503)。
文摘Highly efficient,environmentally friendly,and inexpensive cathode materials have been regarded as the core elements in a wide range of rechargeable alkaline zinc batteries(RAZBs).Herein,a three-dimensional ordered mesoporous nitrogen-doped oxygen-deficient iron trioxide nanoarray(denoted as N-Fe_(2)O_(3)−x)has been developed as a new kind of cathode material for RAZBs,with great promise.The N-Fe_(2)O_(3)−x nanoarray is prepared via a unique high-isostatic pressure-assisted nanocasting process and N_(2) plasma activation,which endow the N-Fe_(2)O_(3)−x material with highly effective areas,abundant active sites,fast electrolyte diffusion channels,and shortened charge transport pathways.Consequently,a high capacity of 288 mA h g^(−1)(at 1.0 A g^(−1))and an excellent energy density of 135 W h kg^(−1)(based on the weights of N-Fe_(2)O_(3)−x)are achieved for the Zn battery composed of N-Fe_(2)O_(3)−x//Zn by using the optimized N-Fe_(2)O_(3)−x material as the cathode and Zn metal as the anode.Moreover,the rechargeable Zn battery possesses excellent stability;at 10 A g^(−1),the battery retains 73%capacitance after 1000 cycles.The excellent electrochemical performance of the N-Fe_(2)O_(3)−x//Zn battery is much higher than those of the current Zn batteries based on iron oxides and hydroxides.This is the first example of using iron trioxide as a cathode for RAZBs,which may be of intense interest to later researchers.
基金supported by the National Key Research and Development Program of China(No.2016YFB 0600904).The authors gratefully acknowledge the support of the Analytical and Test Center of Sichuan University.
文摘Natural magnetite formed by the isomorphism substitutions of transition metals,including Fe,Ti,Co,etc.,was activated by mechanical grinding followed by H2 reduction.The temperature-programmed reduction of hydrogen(H2-TPR)and temperature-programmed surface reaction of carbon dioxide(CO_(2)-TPSR)were carried out to investigate the processes of oxygen loss and CO_(2)reduction.The samples were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM),and energy-dispersive X-ray spectroscopy(EDS).The results showed that the stability of spinel phases and oxygen-deficient degree significantly increased after natural magnetite was mechanically milled and reduced in H2 atmosphere.Meanwhile,the activity and selectivity of CO_(2)reduction into carbon were enhanced.The deposited carbon on the activated natural magnetite was confirmed as amorphous.The amount of carbon after CO_(2)reduction at 300°C for 90 min over the activated natural magnetite was 2.87wt%higher than that over the natural magnetite.
文摘In recent years, considerable progresses have been made in studies on diverseutilizations of carbon dioxide. For carbon dioxide, there are two problems worthy of con-cern: one is the ’greenhouse effect’ caused by carbon dioxide on the earth, the other is
基金supported by the National Key R&D Program of China (Nos.2017YFA0208200,2016YFB0700600,and 2015CB659300)the National Natural Science Foundation of China (Nos.21872069,51761135104,and 21573108)+1 种基金Natural Science Foundation of Jiangsu Province (Nos.BK20180008 and BK20150583)High-Level Entrepreneurial and Innovative Talents Program of Jiangsu Province,and the Fundamental Research Funds for the Central Universities.
文摘Lithium-ion capacitor (LIC) has been regarded as a promising energy storage system with high powder density and high energy density.However,the kinetic mismatch between the anode and the cathode is a major issue to be solved.Here we report a high-performance asymmetric LIC based on oxygen-deficient black-TiO2-x/graphene (B-TiO2-x/G) aerogel anode and biomass derived microporous carbon cathode.Through a facile one-pot hydrothermal process,graphene nanosheets and oxygen-vacancy-rich porous B-TiO2-x/G nanosheets were self-assembled into three-dimensional (3D) interconnected B-TiO2-x/G aerogel.Owing to the rich active sites,high conductivity and fast kinetics,the B-TiO2-x/G aerogel exhibits remarkable reversible capacity,high rate capability and long cycle life when used as anode material for lithium ion storage.Moreover,density functional theory (DFT) calculation reveals that the incorporation of graphene nanosheets can reduce the energy barrier of Li^+ diffusion in B-TiO2-x.The asymmetric LIC based on B-TiO2-x/G aerogel anode and naturally-abundant pine-needles derived microporous carbon (MPC) cathode work well within a large voltage window (1.0-4.0 V),and can deliver high energy density (166.4 Wh·kg^-1 at 200 mA·g^-1),and high power density (7.9 kW·kg^-1 at 17.1 Wh·kg^-1).Moreover,the LIC shows a high capacitance retention of 87% after 3,000cycles at 2,000 mA·g^-1.The outstanding electrochemical performances indicate that the rationally-designed LICs have promising prospect to serve as advanced fast-charging energy storage devices.
基金financially supported by the National Natural Science Foundation of China (51572136, 51772162, 21571112, 51802170 and 21801150)the Natural Science Foundation of Shandong Province (ZR2018BEM014, ZR2018LB008 andZR2019MB001)+2 种基金Taishan Scholar Foundation of Shandong Province (H. W., ts201712047)the Special Fund Project to Guide Development of Local Science and Technology by Central Government (H.W.)Taishan Scholar Program of Advantage and Characteristic Discipline Team of Eco Chemical Process and Technology
文摘Artificial Z-scheme photocatalytic systems have received considerable attention in recent years because they can achieve wide light-absorption, high charge-separation efficiency, and strong redox ability simultaneously. Nevertheless, it is still challenging to exploit low-cost and stable Zscheme photocatalysts with highly-efficient H2 evolution from solar water-splitting so far. Herein, we report a novel all-solidstate Z-scheme photocatalyst Cd1-xZnxS@WO3-x consisting of Cd1-xZnxS nanorods coated with oxygen-deficient WO3-x amorphous layers. The Cd1-xZnxS@WO3-x exhibits an outstanding H2 evolution reaction(HER) activity as compared with Pt-loaded Cd1-xZnxS and most WO3- and Cd S-based photocatalysts, due to the generation of stronger reducing electrons through the appropriate Zn-doping in Cd1-xZnxS and the enhanced charge transfer by introducing oxygen vacancies(W^5+/OVs) into the ultrathin WO3-x amorphous coatings. The optimal HER rate of Cd1-xZnxS@WO3- xis determined to be 21.68 mmol h^-1 g^-1, which is further raised up to 28.25 mmol h^-1 g^-1(about 12 times more than that of Pt/Cd1-xZnxS) when Cd1-xZnxS@WO3-x is hybridized by Co Ox and Ni Oxdual cocatalysts(Cd1-xZnxS@WO3-x/CoOx/NiOx)through in-situ photo-deposition. Moreover, the corresponding apparent quantum yield(AQY) at 420 nm is significantly increased from 34.6% for Cd1-xZnxS@WO3-x to 60.8% for Cd1-xZnxS@WO3-x/CoOx/NiOx. In addition, both Cd1-xZnxS@WO3-x and Cd1-xZnxS@WO3-x/CoOx/NiOx demonstrate good stability towards HER. The results displayed in this work will inspire the rational design and synthesis of high-performance nanostructures for photocatalytic applications.
基金supported by National Basic Research Program of China(973 Program)(Grant No.2014CB7443-02)Specially Founded Program on National Key Scientific Instruments and Equipment Development(Grant No.2012YQ140005)
文摘The La2/3Cal/3Mn03_σ film has been deposited on the （001） SrTiO3 substrate and its temper- ature-dependent photoconductive properties have been investigated from 80 to 300 K. The La2/3Cal/3MnO3-σ film has a novel photoelectric property due to its oxygen-deficient structure. We observed laser-induced giant negative photoresistance of the sample in a wide temperature range. The change rate of negative photoresistance was nearly 100% at the low temperature when the sample was irradiated by 532 nm laser. In addition, this effect was sensitive to the power of laser irradiation. The oxygen-deficiency of La2/3Cal/3Mn03-σ film seems to have an impact on the laser-induced resistance variation. The experimental results made the La2/3Cal/3MnO3_σ film a promising application as a photoswitch device.
