Manganese-based material is a prospective cathode material for aqueous zinc ion batteries(ZIBs)by virtue of its high theoretical capacity,high operating voltage,and low price.However,the manganese dissolution during t...Manganese-based material is a prospective cathode material for aqueous zinc ion batteries(ZIBs)by virtue of its high theoretical capacity,high operating voltage,and low price.However,the manganese dissolution during the electrochemical reaction causes its electrochemical cycling stability to be undesirable.In this work,heterointerface engineering-induced oxygen defects are introduced into heterostructure MnO_(2)(δa-MnO_(2))by in situ electrochemical activation to inhibit manganese dissolution for aqueous zinc ion batteries.Meanwhile,the heterointerface between the disordered amorphous and the crystalline MnO_(2)ofδa-MnO_(2)is decisive for the formation of oxygen defects.And the experimental results indicate that the manganese dissolution ofδa-MnO_(2)is considerably inhibited during the charge/discharge cycle.Theoretical analysis indicates that the oxygen defect regulates the electronic and band structure and the Mn-O bonding state of the electrode material,thereby promoting electron transport kinetics as well as inhibiting Mn dissolution.Consequently,the capacity ofδa-MnO_(2)does not degrade after 100 cycles at a current density of 0.5 Ag^(-1)and also 91%capacity retention after 500cycles at 1 Ag^(-1).This study provides a promising insight into the development of high-performance manganese-based cathode materials through a facile and low-cost strategy.展开更多
The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, ...The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, an anatase cell with a Nb dopant at Ti site （NbTi）, an anatase cell with a Nb-dopant and an oxygen vacancy （NbTi＋Vo）, and an anatase cell with a Nb-dopant and an interstitial oxygen （NbTi＋Oi）） were considered. The density of states, effective mass, Bader charge, charge density, and electron localization function were calcul^ited. The results show that in the NbTi＋Vo cell both eg and t2g levels of Ti 3d orbits make contributions to the electronic conductivity, and the oxygen vacancies （Vo） collaborate with Nb-dopants to favor the high electrical conductivity by inducing the Nb-dopants to release more excess charges. In NbTi＋Oi, an unoccupied impurity level appears in the band gap, which served as an acceptor level and suppressed the electronic conductivity. The results qualitatively coincide with experimental results and possibly provide insights into the preparation of TCOs with desirable conductivity.展开更多
Ti-based materials are among the most widely studied catalysts for the oxygen reduction reaction(ORR).However,the actual roles of the catalytically active sites in N-doped Ti-based electrocatalysts are still unclear.I...Ti-based materials are among the most widely studied catalysts for the oxygen reduction reaction(ORR).However,the actual roles of the catalytically active sites in N-doped Ti-based electrocatalysts are still unclear.In this work,TiO_(2)and TiN were used as the precursors for the thermal nitridation and oxidation reactions at high temperatures,respectively.Titanium oxynitride(TiO_(x)N_(y))species with abundant oxygen defects,formed on the surface of the as-prepared catalysts,were found to play an essential role to achieve the uniform distribution of ultrafine Pt nanoparticles via atomic layer deposition,thereby enhancing the ORR performance.The TiN-supported Pt catalyst showed excellent ORR performance and stability in acidic conditions,with an onset potential of 0.88 V and a half-wave potential of 0.76 V(vs.RHE).The catalyst also delivered a mass activity of 112 A gPt-1,which is 1.9 times higher than that of commercial Pt/C.A combination of experiments and characterizations confirmed that the synergistic effects between the outer TiO_(x)N_(y)shell with abundant oxygen defects and the high-conductivity TiN core contribute to the enhanced ORR performance.The present work sheds light on the essential roles of oxygen defect-rich TiO_(x)N_(y)species in Ti-based electrocatalysts.展开更多
Oxygen defects play a critical role in the electrocatalytic oxygen evolution reaction(OER).Therefore,in-depth understanding the structure-activity-mechanism relationship of these defects is the key to design efficient...Oxygen defects play a critical role in the electrocatalytic oxygen evolution reaction(OER).Therefore,in-depth understanding the structure-activity-mechanism relationship of these defects is the key to design efficient OER electrocatalysts.This relationship needs to be understood dynamically due to the potential for irreversible phase transitions during OER.Consequently,significant efforts have been devoted to study the dynamic evolution of oxygen defects to shed light on the OER mechanism.This review critically examines and analyzes the dynamic processes occurring at oxygen defect sites during OER,including defect formation and defect evolution mechanisms,along with the advanced characterization techniques needed to understand these processes.This review aims to provide a comprehensive understanding of high-efficiency electrocatalysts,with a particular emphasis on the importance of in situ monitoring the dynamic evolution of oxygen defects,providing a new perspective towards efficient OER electrocatalyst design.展开更多
Although some experiments have shown that point defects in a cathode host material may enhance its performance for lithium-sulfur battery(LSB),the enhancement mechanism needs to be well investigated for the design of ...Although some experiments have shown that point defects in a cathode host material may enhance its performance for lithium-sulfur battery(LSB),the enhancement mechanism needs to be well investigated for the design of desired sulfur host.Herein,the first principle density functional theory(DFT)is adopted to investigate a high-performance sulfur host material based on oxygen-defective TiO2(D-TiO2).The adsorption energy comparisons and Gibbs free energy analyses verify that D-TiO2 has relatively better performances than defect-free TiO2 in terms of anchoring effect and catalytic conversion of polysulfides.Meanwhile,D-TiO2 is capable of absorbing the most soluble and diffusive long-chain polysulfides.The newly designed D-TiO2 composited with three-dimensional graphene aerogel(D-TiO2@Gr)has been shown to be an excellent sulfur host,maintaining a specific discharge capacity of 1,049.3 mAhg^−1 after 100 cycles at 1C with a sulfur loading of 3.2 mgcm^−2.Even with the sulfur mass loading increasing to 13.7 mgcm^−2,an impressive stable cycling is obtained with an initial areal capacity of 14.6 mAhcm^−2,confirming the effective enhancement of electrochemical performance by the oxygen defects.The DFT calculations shed lights on the enhancement mechanism of the oxygen defects and provide some guidance for designing advanced sulfur host materials.展开更多
Cost-effectively,eco-friendly rechargeable aqueous zinc-ion batteries(AZIBs)have reserved widespread concerns and become outstanding candidate in energy storage systems.However,the progress pace of AZIBs suffers from ...Cost-effectively,eco-friendly rechargeable aqueous zinc-ion batteries(AZIBs)have reserved widespread concerns and become outstanding candidate in energy storage systems.However,the progress pace of AZIBs suffers from limitation of suitable and affordable cathode materials.Herein,a double-effect strategy is realized in a one-step hydrothermal treatment to prepare V_(2)O_(5)nanoribbons with intercalation of Ce and introduction of abundant oxygen defects(Od-Ce@V_(2)O_(5))to enhance electrochemical performance synergistically.Coupled with the theoretical calculation results,the introduction of Ce ions intercalation and oxygen vacancies in V2O5 structure enhances the electrical conductivity,reduces the adsorption energy of zinc ions,enlarges the interlayer distance,renders the structure more stable,and facilitates rapid diffusion kinetics.As expected,the desirable cathode delivers the reversible capacity of 444 mAh·g^(−1)at 0.5 A·g^(−1)and shows excellent Coulombic efficiency,as well as an extraordinary energy density of 304.9 Wh·kg^(−1).The strategy proposed here may aid in the further development of cathode materials with stable performance for AZIBs.展开更多
Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite n...Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite nanoparticles with a size of <10 nm, but this phase can be eliminated after the air annealing treatment. The atom ratio of Zn/Fe and concentration of oxygen vacancies decrease as the particle size of zinc ferrite increases, causing magnetic transition from superparamagnetism to ferromagnetism. The X-ray magnetic circular dichroism spectra reveal that the spin magnetic moments of Fe^(3+)are reduced, and the orbital magnetic moments are frozen with the increasing atom ratio of Zn/Fe. Therefore,saturation magnetization decreases. The saturation magnetizations of all the zinc ferrite nanoparticles decrease after the air annealing treatment, suggesting that oxygen vacancies considerably influence the magnetic properties. The air annealing treatment can minimize the number of oxygen defects,which trigger some of the Fe^(3+)–OV–Fe^(3+)ferrimagnetic couplings to transfer into the Fe^(3+)–O^(2-)–Fe^(3+)antiferromagnetic couplings. This work provides new insights regarding the magnetic performance of spinel ferrites by tuning the stoichiometric ratio and oxygen defects.展开更多
Though oxygen defects are associated with deteriorated structures and aggravated cycling performance in traditional layered cathodes,the role of oxygen defects is still ambiguous in Li-rich layered oxides due to the i...Though oxygen defects are associated with deteriorated structures and aggravated cycling performance in traditional layered cathodes,the role of oxygen defects is still ambiguous in Li-rich layered oxides due to the involvement of oxygen redox.Herein,a Co-free Li-rich layered oxide Li_(1.286)Ni_(0.071)Mn_(0.643)O_(2)has been prepared by a co-precipitation method to systematically investigate the undefined effects of the oxygen defects.A significant O_(2)release and the propagation of oxygen vacancies were detected by operando differential electrochemical mass spectroscopy(DEMS)and electron energy loss spectroscopy(EELS),respectively.Scanning transmission electron microscopy-high angle annular dark field(STEMHAADF)reveals the oxygen vacancies fusing to nanovoids and monitors a stepwise electrochemical activation process of the large Li_(2)MnO_(3)domain upon cycling.Combined with the quantitative analysis conducted by the energy dispersive spectrometer(EDS),existed nano-scale oxygen defects actually expose more surface to the electrolyte for facilitating the electrochemical activation and subsequently increasing available capacity.Overall,this work persuasively elucidates the function of oxygen defects on oxygen redox in Co-free Li-rich layered oxides.展开更多
Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ra...Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ratio on the structure,optical property,surface morphology,and chemical bonding properties of the a-Ga_(2)O_(3) films was investigated.Results show that the average optical transmittance of the a-Ga_(2)O_(3) films is over 80%within the wavelength range of 300-2000 nm.The extracted optical band gap of the a-Ga_(2)O_(3) films is increased from 4.97 eV to 5.13 eV with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,due to the decrease in concentration of oxygen vacancy defects in the film.Furthermore,the optical refractive index and surface roughness of the a-Ga_(2)O_(3) films are optimized when the O_(2)/Ar flow rate ratio reaches 0.25.X-ray photoelectron spectroscopy analysis also shows that the proportion of oxygen vacancies(VO)and Ga-O chemical bonds in the O 1s peak is gradually decreased with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,proving that increasing the O_(2)/Ar flow rate ratio during film growth can reduce the concentration of oxygen vacancy defects in a-Ga_(2)O_(3) films.In this case,a-Ga_(2)O_(3) with optimal properties can be obtained.This work provides a research basis for high-performance flexible and rigid deep ultraviolet solar-blind detection devices based on a-Ga_(2)O_(3) films.展开更多
Recently,high-entropy materials are attracting enormous attention in battery applications,encompassing both electrode materials and solid electrolytes,due to the pliability and diversification in material composition ...Recently,high-entropy materials are attracting enormous attention in battery applications,encompassing both electrode materials and solid electrolytes,due to the pliability and diversification in material composition and electronic structure.Theoretically,the rapid ion transport and the abundance of surface defects in high-entropy materials suggest a potential for enhancing the performance of composite solid-state electrolytes(CPEs).Herein,using a high-entropy oxide(HEO)filler to assess its potential contributions to CPEs is proposed.The distinctive structural distortions in HEO significantly improve the ionic conductivity(5×10^(−4) S·cm^(−1) at 60℃)and Li-ion transference number(0.57)of CPEs.Furthermore,the enhanced Li-ion transport capability extends the critical current density from 0.6 to 1.5 mA·cm^(−2) in Li/Li symmetric cells.In addition,all-solid-state batteries incorporating the HEO-modified CPEs exhibit superior rate performance and cycling stability.The work will enrich the application of HEOs in CPEs and provide fundamental understanding.展开更多
Recent years have witnessed a booming interest in grid-scale electrochemical energy storage,where much attention has been paid to the aqueous zinc ion batteries(AZIBs).Among various cathode materials for AZIBs,mangane...Recent years have witnessed a booming interest in grid-scale electrochemical energy storage,where much attention has been paid to the aqueous zinc ion batteries(AZIBs).Among various cathode materials for AZIBs,manganese oxides have risen to prominence due to their high energy density and low cost.However,sluggish reaction kinetics and poor cycling stability dictate against their practical application.Herein,we demonstrate the combined use of defect engineering and interfacial optimization that can simultaneously promote rate capability and cycling stability of MnO_(2) cathodes.β-MnO_(2) with abundant oxygen vacancies(VO)and graphene oxide(GO)wrapping is synthesized,in which VO in the bulk accelerate the charge/discharge kinetics while GO on the surfaces inhibits the Mn dissolution.This electrode shows a sustained reversible capacity of~129.6 mAh g^(−1) even after 2000 cycles at a current rate of 4C,outperforming the state-of-the-art MnO_(2)-based cathodes.The superior performance can be rationalized by the direct interaction between surface VO and the GO coating layer,as well as the regulation of structural evolution ofβ-MnO_(2) during cycling.The combinatorial design scheme in this work offers a practical pathway for obtaining high-rate and long-life cathodes for AZIBs.展开更多
The structural engineering of hydrated ammonium vanadate as a cathode for aqueous Zn-ion batteries has attracted significant research interest because of its ability to suppress vanadium dissolution and accelerate the...The structural engineering of hydrated ammonium vanadate as a cathode for aqueous Zn-ion batteries has attracted significant research interest because of its ability to suppress vanadium dissolution and accelerate the electrochemical dynamics.Herein,a feasible fabrication strategy for oxygen-deficient(NH_(4))_(2)V_(10)O_(25)·xH_(2)O/GO(NVOH@GO)composites was proposed,and the charge storage mechanism was discussed.The results of characterization analysis showed that the introduction of graphene oxide(GO)not only enlarged the layer spacing and improved electrical conductivity,providing spacious channels for Zn^(2+)(de)intercalation and accelerating the ion diffusion dynamics,but also induced more oxygen vacancies,inhibited the dissolution of vanadium,and reduced self-discharging,offering additional and stable active sites for ion storage.The optimized NVOH@GO electrode delivered extraordinarily stable capacities of 334 mAh·g^(-1)after 2000 cycles at 5 A·g^(-1)and 238 mAh·g^(-1)after 10,000cycles at 20 A·g^(-1).Furthermore,ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and Raman results systematically revealed the electrochemical mechanism,including a phase transition reaction and subsequent Zn^(2+)/H_(2)O co-(de)intercalation process.This study provides an effective strategy for expanding the interlayer spacing,inducing defect engineering,and enhancing the structural stability of vanadium-based cathodes for Zn-ion batteries and other multivalent aqueous ion batteries.展开更多
Although MgH_(2) has been widely regarded as a promising material for solid-state hydrogen storage,its high operating temperature and slow kinetics pose a major bottleneck to its practical application.Here,a nanocompo...Although MgH_(2) has been widely regarded as a promising material for solid-state hydrogen storage,its high operating temperature and slow kinetics pose a major bottleneck to its practical application.Here,a nanocomposite catalyst with interfacial coupling and oxygen defects,Ni/CeO_(2),is fabricated to promote H_(2) desorption and absorption properties of MgH_(2).The interface of Ni/CeO_(2) contributes to both strong mechanical coupling towards stabilizing partial Ni and electronic coupling towards inducing a high con-centration of oxygen vacancies in CeO_(2).Theoretical calculations evidence that CeO_(2) with oxygen vacancy assist Ni in weakening the energy of Mg-H bond as well as enhancing the adsorption energy of Ni upon hydrogen atoms,and the extent of this assistance surprisingly increases with increasing oxygen vacancies concentration.As a result,an impressive performance is achieved by MgH_(2)-5 wt.%Ni/CeO_(2) with onset desorption temperature of only 165°C,and it absorbs approximately 80%hydrogen in just 800 s at 125°C.The generation mechanism of intermediate active species concerning Ni/CeO_(2) in different states has been analyzed for the first time,and the relationship between interfacial coupling and phase evolution has been elucidated.Therefore,a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed.It is believed that this work provides a unique perspective on the mechanism of interfacial coupling and the generation of defects in composite catalysts.展开更多
Construction of oxygen evolution electrocatalysts with abundant oxygen defects and large specific surface areas can significantly improve the conversion efficiency of overall water splitting.Herein,we adopt a controll...Construction of oxygen evolution electrocatalysts with abundant oxygen defects and large specific surface areas can significantly improve the conversion efficiency of overall water splitting.Herein,we adopt a controlled method to prepare oxygen defect-rich double-layer hierarchical porous Co3O4 arrays on nickel foam(DL-Co3O4/NF)for water splitting.The unique array-like structure,crystallinity,porosity,and chemical states have been carefully investigated through SEM,TEM,XRD,BET,and XPS techniques.The designated DL-Co3O4/NF has oxygen defects of up to 67.7%and a large BET surface area(57.4 m2g-1).Electrochemical studies show that the catalyst only requires an overpotential of 256 mV to reach 20 mA cm-2,as well as a small Tafel slope of 60.8 mV dec-1,which is far better than all control catalysts.Besides,the catalyst also demonstrates excellent overall water splitting performance in a two-electrode system and good long-term stability,far superior to most previously reported catalysts.Electrocatalytic mechanisms indicate that abundant oxygen vacancies provide more active sites and good conductivity.At the same time,the unique porous arrays facilitate electrolyte transport and gas emissions,thereby synergistically improving OER catalytic performance.展开更多
Perovskite oxides with diverse composition and structure have exhibited grand advances in boosting the oxygen reduction and evolution reaction(ORR/OER),which are essential for the reversible protonic ceramic electroch...Perovskite oxides with diverse composition and structure have exhibited grand advances in boosting the oxygen reduction and evolution reaction(ORR/OER),which are essential for the reversible protonic ceramic electrochemical cell(R-PCEC)toward the sustainable hydrogen production and utilization.However,enhancement of their activity and stability remains challenging.Herein,we develop the Ta-regulated BaCo_(0.7)Fe_(0.3)O_(3-δ)perovskite oxygen electrode(Ba(Co_(0.7)Fe_(0.3))_(1-x)Ta_xO_(3-δ))with abundant oxygen defects and achieve the simultaneous enhancement in the electrocatalytic activity and stability toward ORR and OER.As-fabricated R-PCEC with(Ba(Co_(0.7)Fe_(0.3))_(0.9)Ta_(0.1)O_(3-δ))(BCFT10)oxygen electrode performs high power density of 1.47 W·cm^(-2)at 650℃in fuel cell mode,and the current density is up to-2.11 A·cm^(-2)at 1.4 V at 650℃in electrolysis mode,as well as the good stability in both the fuel cell and electrolysis modes.Importantly,the cell also demonstrates a stable cycling operation between fuel cell and electrolysis mode,suggesting a great potential of BCFT10 as oxygen electrode material for R-PCECs.展开更多
Aqueous zinc-ion batteries(AZIBs)have attracted widespread attention due to the advantages of high safety and environmental friendliness.Although V_(2)O_(3) is a promising cathode,the strong electrostatic interaction ...Aqueous zinc-ion batteries(AZIBs)have attracted widespread attention due to the advantages of high safety and environmental friendliness.Although V_(2)O_(3) is a promising cathode,the strong electrostatic interaction between Zn^(2+) and V_(2)O_(3) crystal,and the sluggish reaction kinetics still limit their application in AZIBs.Herein,the oxygen defects rich V_(2)O_(3) with conducive poly(3,4-ethylenedioxythiophene)(PEDOT)shell(V_(2)O_(3)-Od@PEDOT)was fabricated for AZIBs by combining the sulfur-assisted thermal reduction and in-situ polymerization method.The introduced oxygen vacancies of V_(2)O_(3)–Od@PEDOT weaken the electrostatic interaction between Zn^(2+) and the host material,improving the interfacial electron transport,while the PEDOT coating enhances the structural stability and conductivity of V_(2)O_(3),thus accelerating the reaction kinetics.Based on the advantages,V_(2)O_(3)–Od@PEDOT electrode delivers a reversible capacity of 495 mAh·g^(−1) at 0.1 A·g^(−1),good rate capability(189 mAh·g^(−1)at 8.0 A·g^(−1)),and an impressive cycling stability with 90.1%capacity retention over 1000 cycles at 8.0 A·g^(−1).The strategy may provide a path for exploiting the other materials for high performance AZIBs.展开更多
Defect engineering is in the limelight for the fabrication of electrochemical energy storage devices.However,determining the influence of the defect density and location on the electrochemical behavior remains challen...Defect engineering is in the limelight for the fabrication of electrochemical energy storage devices.However,determining the influence of the defect density and location on the electrochemical behavior remains challenging.Herein,self-organized TiO_(2)nanotube arrays(TNTAs)are synthesized by anodization,and their oxygen defect location and density are tuned by a controllable post-annealing process.TNTAs annealed at 600℃ in N2 exhibit the highest capacity(289.2 m Ah g^(-1)at 0.8 C)for lithium-ion storage,while those annealed at 900℃ in N2 show a specific capacitance of 35.6 m F cm^(-2)and stability above96%after 10,000 cycles for supercapacitor.Ex situ electron paramagnetic resonance spectra show that the surface-exposed oxygen defects increase,but the bulk embedded oxygen defects decrease with increasing annealing temperature.Density functional theory simulations reveal that a higher density of bulk oxygen defects corresponds to higher localized electrons states,which upshift the Fermi level and facilitate the lithium intercalation kinetic process.Meanwhile,differential charge density calculation indicates that the increase of surface oxygen defects in the anatase(101)plane leads to higher density excess electrons,which act as negative charge centers to enhance the surface potential for ion adsorption.This oxygen-deficient location and density tunable strategy introduce new opportunities for high-energy and high-power-density energy storage systems.展开更多
The alkaline zinc-based batteries with high energy density are becoming a research hotspot.However,the poor cycle stability and low-rate performance limit their wide application.Herein,ultra-thin CoNiO2 nanosheet with...The alkaline zinc-based batteries with high energy density are becoming a research hotspot.However,the poor cycle stability and low-rate performance limit their wide application.Herein,ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays(Od-CNO@Ni NTs)is used as a positive material for rechargeable alkaline Ni–Zn batteries.As the highly uniform Ni nanotube arrays provide a fast electron/ion transport path and abundant active sites,the Od-CNO@Ni NTs electrode delivers excellent capacity(432.7 mAh g^(−1))and rate capability(218.3 mAh g^(−1)at 60 A g^(−1)).Moreover,our Od-CNO@Ni NTs//Zn battery is capable of an ultra-long lifespan(93.0%of initial capacity after 5000 cycles),extremely high energy density of 547.5 Wh kg^(−1)and power density of 92.9 kW kg^(−1)(based on the mass of cathode active substance).Meanwhile,the theoretical calculations reveal that the oxygen defects can enhance the interaction between electrode surface and electrolyte ions,contributing to higher capacity.This work opens a reasonable idea for the development of ultra-durable,ultra-fast,and high-energy Ni–Zn battery.展开更多
For CO catalytic oxidation,Cu and Ce species are of great importance,between which the synergistic effect is worth investigating.In this work,CeO_(2)/Cu_(2)O with Cu_(2)O{111}and{100}planes were comparatively explored...For CO catalytic oxidation,Cu and Ce species are of great importance,between which the synergistic effect is worth investigating.In this work,CeO_(2)/Cu_(2)O with Cu_(2)O{111}and{100}planes were comparatively explored on CO catalytic oxidation to reveal the effects of interfacial electronic interactions and oxygen defects.The activity result demonstrates that CeO_(2)/o-Cu_(2)O{111}has superior performance compared with CeO_(2)/c-Cu_(2)O{100}.Credit to the coordination unsaturated copper atoms(Cu_(CUS))on oCu_(2)O{111}surface,the interfacial electronic interactions on CeO_(2)/o-Cu_(2)O{111}are more obvious than those on CeO_(2)/c-Cu_(2)O{100},leading to richer oxygen defect generation,better redox and activation abilities of CO and O_(2)reactants.Furthermore,the reaction mechanism of CeO_(2)/o-Cu_(2)O{111}on CO oxidation is revealed,i.e.,CO and O_(2)are adsorbed on the Cucus on Cu_(2)O{111}and oxygen defect of CeO_(2),respectively,and then synergistically promote the CO oxidation to CO_(2).The work sheds light on the designing optimized ceria and copper-based catalysts and the mechanism of CO oxidation.展开更多
The rational design of oxygen vacancies and electronic microstructures of electrode materials for energy storage devices still remains a challenge. Herein, we synthesize nickel cobalt-based oxides nanoflower arrays as...The rational design of oxygen vacancies and electronic microstructures of electrode materials for energy storage devices still remains a challenge. Herein, we synthesize nickel cobalt-based oxides nanoflower arrays assembled with nanowires grown on Ni foam via the hydrothermal process followed annealing process in air and argon atmospheres respectively. It is found that the annealing atmosphere has a vital influence on the oxygen vacancies and electronic microstructures of resulting NiCo_(2)O_(4) (NCO-Air) and CoNiO_(2) (NCO-Ar) products, which NCO-Ar has more oxygen vacancies and larger specific surface area of 163.48 m^(2)/g. The density functional theory calculation reveals that more oxygen vacancies can provide more electrons to adsorb –OH free anions resulting in superior electrochemical energy storage performance. Therefore, the assembled asymmetric supercapacitor of NCO-Ar//active carbon delivers an excellent energy density of 112.52 Wh/kg at a power density of 558.73 W/kg and the fabricated NCO-Ar//Zn battery presents the specific capacity of 180.20 mAh/g and energy density of 308.14 Wh/kg. The experimental measurement and theoretical calculation not only provide a facile strategy to construct flower-like mesoporous architectures with massive oxygen vacancies, but also demonstrate that NCO-Ar is an ideal electrode material for the next generation of energy storage devices.展开更多
基金funds from the National Natural Science Foundation of China(51772082 and 51804106)the Natural Science Foundation of Hunan Province(2023JJ10005)
文摘Manganese-based material is a prospective cathode material for aqueous zinc ion batteries(ZIBs)by virtue of its high theoretical capacity,high operating voltage,and low price.However,the manganese dissolution during the electrochemical reaction causes its electrochemical cycling stability to be undesirable.In this work,heterointerface engineering-induced oxygen defects are introduced into heterostructure MnO_(2)(δa-MnO_(2))by in situ electrochemical activation to inhibit manganese dissolution for aqueous zinc ion batteries.Meanwhile,the heterointerface between the disordered amorphous and the crystalline MnO_(2)ofδa-MnO_(2)is decisive for the formation of oxygen defects.And the experimental results indicate that the manganese dissolution ofδa-MnO_(2)is considerably inhibited during the charge/discharge cycle.Theoretical analysis indicates that the oxygen defect regulates the electronic and band structure and the Mn-O bonding state of the electrode material,thereby promoting electron transport kinetics as well as inhibiting Mn dissolution.Consequently,the capacity ofδa-MnO_(2)does not degrade after 100 cycles at a current density of 0.5 Ag^(-1)and also 91%capacity retention after 500cycles at 1 Ag^(-1).This study provides a promising insight into the development of high-performance manganese-based cathode materials through a facile and low-cost strategy.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51002135 and 51172200)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant No.2013QNA4011)
文摘The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, an anatase cell with a Nb dopant at Ti site （NbTi）, an anatase cell with a Nb-dopant and an oxygen vacancy （NbTi＋Vo）, and an anatase cell with a Nb-dopant and an interstitial oxygen （NbTi＋Oi）） were considered. The density of states, effective mass, Bader charge, charge density, and electron localization function were calcul^ited. The results show that in the NbTi＋Vo cell both eg and t2g levels of Ti 3d orbits make contributions to the electronic conductivity, and the oxygen vacancies （Vo） collaborate with Nb-dopants to favor the high electrical conductivity by inducing the Nb-dopants to release more excess charges. In NbTi＋Oi, an unoccupied impurity level appears in the band gap, which served as an acceptor level and suppressed the electronic conductivity. The results qualitatively coincide with experimental results and possibly provide insights into the preparation of TCOs with desirable conductivity.
基金supported by the National Natural Science Foundation of China(52225204 and 52173233)the Natural Science Foundation of Shanghai(23ZR1479200)+3 种基金the Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-03-E00109)“Shuguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(20SG33)the DHU Distinguished Young Professor Program.Q.X.acknowledges the Shanghai Pujiang Program(21PJ1400400)the Research Start-up Fund at DHU,and the Fundamental Research Funds for the Central Universities.H.D.U.acknowledges the 2022 Research Grant from Kangwon National University.
文摘Ti-based materials are among the most widely studied catalysts for the oxygen reduction reaction(ORR).However,the actual roles of the catalytically active sites in N-doped Ti-based electrocatalysts are still unclear.In this work,TiO_(2)and TiN were used as the precursors for the thermal nitridation and oxidation reactions at high temperatures,respectively.Titanium oxynitride(TiO_(x)N_(y))species with abundant oxygen defects,formed on the surface of the as-prepared catalysts,were found to play an essential role to achieve the uniform distribution of ultrafine Pt nanoparticles via atomic layer deposition,thereby enhancing the ORR performance.The TiN-supported Pt catalyst showed excellent ORR performance and stability in acidic conditions,with an onset potential of 0.88 V and a half-wave potential of 0.76 V(vs.RHE).The catalyst also delivered a mass activity of 112 A gPt-1,which is 1.9 times higher than that of commercial Pt/C.A combination of experiments and characterizations confirmed that the synergistic effects between the outer TiO_(x)N_(y)shell with abundant oxygen defects and the high-conductivity TiN core contribute to the enhanced ORR performance.The present work sheds light on the essential roles of oxygen defect-rich TiO_(x)N_(y)species in Ti-based electrocatalysts.
基金supported by the Ministry of Science and Technology(MOST)of China through the Key Project of Research&Development(2021YFF0500502)。
文摘Oxygen defects play a critical role in the electrocatalytic oxygen evolution reaction(OER).Therefore,in-depth understanding the structure-activity-mechanism relationship of these defects is the key to design efficient OER electrocatalysts.This relationship needs to be understood dynamically due to the potential for irreversible phase transitions during OER.Consequently,significant efforts have been devoted to study the dynamic evolution of oxygen defects to shed light on the OER mechanism.This review critically examines and analyzes the dynamic processes occurring at oxygen defect sites during OER,including defect formation and defect evolution mechanisms,along with the advanced characterization techniques needed to understand these processes.This review aims to provide a comprehensive understanding of high-efficiency electrocatalysts,with a particular emphasis on the importance of in situ monitoring the dynamic evolution of oxygen defects,providing a new perspective towards efficient OER electrocatalyst design.
基金This work was supported by the Excellent Dissertation Cultivation Funds of Wuhan University of Technology(No.2018-YS-013).
文摘Although some experiments have shown that point defects in a cathode host material may enhance its performance for lithium-sulfur battery(LSB),the enhancement mechanism needs to be well investigated for the design of desired sulfur host.Herein,the first principle density functional theory(DFT)is adopted to investigate a high-performance sulfur host material based on oxygen-defective TiO2(D-TiO2).The adsorption energy comparisons and Gibbs free energy analyses verify that D-TiO2 has relatively better performances than defect-free TiO2 in terms of anchoring effect and catalytic conversion of polysulfides.Meanwhile,D-TiO2 is capable of absorbing the most soluble and diffusive long-chain polysulfides.The newly designed D-TiO2 composited with three-dimensional graphene aerogel(D-TiO2@Gr)has been shown to be an excellent sulfur host,maintaining a specific discharge capacity of 1,049.3 mAhg^−1 after 100 cycles at 1C with a sulfur loading of 3.2 mgcm^−2.Even with the sulfur mass loading increasing to 13.7 mgcm^−2,an impressive stable cycling is obtained with an initial areal capacity of 14.6 mAhcm^−2,confirming the effective enhancement of electrochemical performance by the oxygen defects.The DFT calculations shed lights on the enhancement mechanism of the oxygen defects and provide some guidance for designing advanced sulfur host materials.
基金financial support provided by the National Natural Science Foundation of China(Nos.U21A2077,21971145,and 21871164)the Taishan Scholar Project Foundation of Shandong Province(No.ts20190908)+1 种基金the Natural Science Foundation of Shandong Province(Nos.ZR2021ZD05 and ZR2019MB024)Young Scholars Program of Shandong University(No.2017WLJH15).
文摘Cost-effectively,eco-friendly rechargeable aqueous zinc-ion batteries(AZIBs)have reserved widespread concerns and become outstanding candidate in energy storage systems.However,the progress pace of AZIBs suffers from limitation of suitable and affordable cathode materials.Herein,a double-effect strategy is realized in a one-step hydrothermal treatment to prepare V_(2)O_(5)nanoribbons with intercalation of Ce and introduction of abundant oxygen defects(Od-Ce@V_(2)O_(5))to enhance electrochemical performance synergistically.Coupled with the theoretical calculation results,the introduction of Ce ions intercalation and oxygen vacancies in V2O5 structure enhances the electrical conductivity,reduces the adsorption energy of zinc ions,enlarges the interlayer distance,renders the structure more stable,and facilitates rapid diffusion kinetics.As expected,the desirable cathode delivers the reversible capacity of 444 mAh·g^(−1)at 0.5 A·g^(−1)and shows excellent Coulombic efficiency,as well as an extraordinary energy density of 304.9 Wh·kg^(−1).The strategy proposed here may aid in the further development of cathode materials with stable performance for AZIBs.
基金financially supported by the National Natural Science Foundation of China (51572218,11504293 and 11904275)the Natural Science Foundation of Shaanxi Province (2019JM-138)+1 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department (18JK0786,19JK0413 and 20JK0946)the Key Project of Research and Development of Shaanxi Province (2018ZDCXL-GY-08-05)。
文摘Monodisperse nonstoichiometric zinc ferrite nanoparticles with a tunable size of 4.1–32.2 nm are fabricated via thermal decomposition. An extrinsic impurity phase of the ZnO component is present in the zinc ferrite nanoparticles with a size of <10 nm, but this phase can be eliminated after the air annealing treatment. The atom ratio of Zn/Fe and concentration of oxygen vacancies decrease as the particle size of zinc ferrite increases, causing magnetic transition from superparamagnetism to ferromagnetism. The X-ray magnetic circular dichroism spectra reveal that the spin magnetic moments of Fe^(3+)are reduced, and the orbital magnetic moments are frozen with the increasing atom ratio of Zn/Fe. Therefore,saturation magnetization decreases. The saturation magnetizations of all the zinc ferrite nanoparticles decrease after the air annealing treatment, suggesting that oxygen vacancies considerably influence the magnetic properties. The air annealing treatment can minimize the number of oxygen defects,which trigger some of the Fe^(3+)–OV–Fe^(3+)ferrimagnetic couplings to transfer into the Fe^(3+)–O^(2-)–Fe^(3+)antiferromagnetic couplings. This work provides new insights regarding the magnetic performance of spinel ferrites by tuning the stoichiometric ratio and oxygen defects.
基金supported by the National Natural Science Foundation of China(52272253)the"Lingyan"Research and Development Plan of Zhejiang Province(2022C01071)+2 种基金the S&T Innovation 2025 Major Special Programme of Ningbo(2018B10081)the Natural Science Foundation of Ningbo(202003N4030)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022299)。
文摘Though oxygen defects are associated with deteriorated structures and aggravated cycling performance in traditional layered cathodes,the role of oxygen defects is still ambiguous in Li-rich layered oxides due to the involvement of oxygen redox.Herein,a Co-free Li-rich layered oxide Li_(1.286)Ni_(0.071)Mn_(0.643)O_(2)has been prepared by a co-precipitation method to systematically investigate the undefined effects of the oxygen defects.A significant O_(2)release and the propagation of oxygen vacancies were detected by operando differential electrochemical mass spectroscopy(DEMS)and electron energy loss spectroscopy(EELS),respectively.Scanning transmission electron microscopy-high angle annular dark field(STEMHAADF)reveals the oxygen vacancies fusing to nanovoids and monitors a stepwise electrochemical activation process of the large Li_(2)MnO_(3)domain upon cycling.Combined with the quantitative analysis conducted by the energy dispersive spectrometer(EDS),existed nano-scale oxygen defects actually expose more surface to the electrolyte for facilitating the electrochemical activation and subsequently increasing available capacity.Overall,this work persuasively elucidates the function of oxygen defects on oxygen redox in Co-free Li-rich layered oxides.
基金Research Project of Shenzhen Science and Technology Innovation Committee(JCYJ20180306170801080)。
文摘Amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))thin films were prepared on flexible polyimide,rigid quartz glass,and Si substrates via radio frequency magnetron sputtering at room temperature.The effect of oxygen/Ar flow rate ratio on the structure,optical property,surface morphology,and chemical bonding properties of the a-Ga_(2)O_(3) films was investigated.Results show that the average optical transmittance of the a-Ga_(2)O_(3) films is over 80%within the wavelength range of 300-2000 nm.The extracted optical band gap of the a-Ga_(2)O_(3) films is increased from 4.97 eV to 5.13 eV with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,due to the decrease in concentration of oxygen vacancy defects in the film.Furthermore,the optical refractive index and surface roughness of the a-Ga_(2)O_(3) films are optimized when the O_(2)/Ar flow rate ratio reaches 0.25.X-ray photoelectron spectroscopy analysis also shows that the proportion of oxygen vacancies(VO)and Ga-O chemical bonds in the O 1s peak is gradually decreased with the increase in O_(2)/Ar flow rate ratio from 0 to 0.25,proving that increasing the O_(2)/Ar flow rate ratio during film growth can reduce the concentration of oxygen vacancy defects in a-Ga_(2)O_(3) films.In this case,a-Ga_(2)O_(3) with optimal properties can be obtained.This work provides a research basis for high-performance flexible and rigid deep ultraviolet solar-blind detection devices based on a-Ga_(2)O_(3) films.
基金supported by the National Natural Science Foundation of China(No.52002094)Shenzhen Science and Technology Program(Nos.JCYJ20210324121411031,JSGG202108021253804014 and RCBS20210706092218040)Shenzhen Steady Support Plan(Nos.GXWD20221030205923001 and GXWD20201230155427003-20200824103000001).
文摘Recently,high-entropy materials are attracting enormous attention in battery applications,encompassing both electrode materials and solid electrolytes,due to the pliability and diversification in material composition and electronic structure.Theoretically,the rapid ion transport and the abundance of surface defects in high-entropy materials suggest a potential for enhancing the performance of composite solid-state electrolytes(CPEs).Herein,using a high-entropy oxide(HEO)filler to assess its potential contributions to CPEs is proposed.The distinctive structural distortions in HEO significantly improve the ionic conductivity(5×10^(−4) S·cm^(−1) at 60℃)and Li-ion transference number(0.57)of CPEs.Furthermore,the enhanced Li-ion transport capability extends the critical current density from 0.6 to 1.5 mA·cm^(−2) in Li/Li symmetric cells.In addition,all-solid-state batteries incorporating the HEO-modified CPEs exhibit superior rate performance and cycling stability.The work will enrich the application of HEOs in CPEs and provide fundamental understanding.
基金This work is financially supported by the Stable Support Funding for Universities in Shenzhen(Nos.GXWD20201231165807007-20200807111854001).
文摘Recent years have witnessed a booming interest in grid-scale electrochemical energy storage,where much attention has been paid to the aqueous zinc ion batteries(AZIBs).Among various cathode materials for AZIBs,manganese oxides have risen to prominence due to their high energy density and low cost.However,sluggish reaction kinetics and poor cycling stability dictate against their practical application.Herein,we demonstrate the combined use of defect engineering and interfacial optimization that can simultaneously promote rate capability and cycling stability of MnO_(2) cathodes.β-MnO_(2) with abundant oxygen vacancies(VO)and graphene oxide(GO)wrapping is synthesized,in which VO in the bulk accelerate the charge/discharge kinetics while GO on the surfaces inhibits the Mn dissolution.This electrode shows a sustained reversible capacity of~129.6 mAh g^(−1) even after 2000 cycles at a current rate of 4C,outperforming the state-of-the-art MnO_(2)-based cathodes.The superior performance can be rationalized by the direct interaction between surface VO and the GO coating layer,as well as the regulation of structural evolution ofβ-MnO_(2) during cycling.The combinatorial design scheme in this work offers a practical pathway for obtaining high-rate and long-life cathodes for AZIBs.
基金financially supported by the Natural Science Foundations of China (Nos.51904152 and42002040)Natural Science Foundations of Henan Province (No.222300420502)+1 种基金Key Science and Technology Program of Henan Province (No.222102240044)Key Scientific Research Projects in Colleges and Universities of Henan Province (No.21B610010)。
文摘The structural engineering of hydrated ammonium vanadate as a cathode for aqueous Zn-ion batteries has attracted significant research interest because of its ability to suppress vanadium dissolution and accelerate the electrochemical dynamics.Herein,a feasible fabrication strategy for oxygen-deficient(NH_(4))_(2)V_(10)O_(25)·xH_(2)O/GO(NVOH@GO)composites was proposed,and the charge storage mechanism was discussed.The results of characterization analysis showed that the introduction of graphene oxide(GO)not only enlarged the layer spacing and improved electrical conductivity,providing spacious channels for Zn^(2+)(de)intercalation and accelerating the ion diffusion dynamics,but also induced more oxygen vacancies,inhibited the dissolution of vanadium,and reduced self-discharging,offering additional and stable active sites for ion storage.The optimized NVOH@GO electrode delivered extraordinarily stable capacities of 334 mAh·g^(-1)after 2000 cycles at 5 A·g^(-1)and 238 mAh·g^(-1)after 10,000cycles at 20 A·g^(-1).Furthermore,ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and Raman results systematically revealed the electrochemical mechanism,including a phase transition reaction and subsequent Zn^(2+)/H_(2)O co-(de)intercalation process.This study provides an effective strategy for expanding the interlayer spacing,inducing defect engineering,and enhancing the structural stability of vanadium-based cathodes for Zn-ion batteries and other multivalent aqueous ion batteries.
基金the National Natural Science Foundation of China(Nos.52071177 and 52171214)National Key R&D Program of China(No.2022YFB3803801)+1 种基金Postgrad-uate Research Practice Innovation Program of Jiangsu Province(No.KYCX22-1289)the Priority Academic Program Development (PAPD) of J iangsu Higher Education Institutions . The computational resources generously provided by the High Performance Comput- ing Center of Nanjing Tech University are greatly appreciated.
文摘Although MgH_(2) has been widely regarded as a promising material for solid-state hydrogen storage,its high operating temperature and slow kinetics pose a major bottleneck to its practical application.Here,a nanocomposite catalyst with interfacial coupling and oxygen defects,Ni/CeO_(2),is fabricated to promote H_(2) desorption and absorption properties of MgH_(2).The interface of Ni/CeO_(2) contributes to both strong mechanical coupling towards stabilizing partial Ni and electronic coupling towards inducing a high con-centration of oxygen vacancies in CeO_(2).Theoretical calculations evidence that CeO_(2) with oxygen vacancy assist Ni in weakening the energy of Mg-H bond as well as enhancing the adsorption energy of Ni upon hydrogen atoms,and the extent of this assistance surprisingly increases with increasing oxygen vacancies concentration.As a result,an impressive performance is achieved by MgH_(2)-5 wt.%Ni/CeO_(2) with onset desorption temperature of only 165°C,and it absorbs approximately 80%hydrogen in just 800 s at 125°C.The generation mechanism of intermediate active species concerning Ni/CeO_(2) in different states has been analyzed for the first time,and the relationship between interfacial coupling and phase evolution has been elucidated.Therefore,a mechanism of the catalysis-assisting effect regarding oxygen defects is proposed.It is believed that this work provides a unique perspective on the mechanism of interfacial coupling and the generation of defects in composite catalysts.
基金supported by the National Natural Science Foundation of China (no.21965005)Natural Science Foundation of Guangxi Province (2018GXNSFAA294077, 2018GXNSFAA281220)+1 种基金Project of High-Level Talents of Guangxi (FKA18015, 2018ZD004)Innovation Project of Guangxi Graduate Education (XYCSZ2019056, YCBZ2019031)。
文摘Construction of oxygen evolution electrocatalysts with abundant oxygen defects and large specific surface areas can significantly improve the conversion efficiency of overall water splitting.Herein,we adopt a controlled method to prepare oxygen defect-rich double-layer hierarchical porous Co3O4 arrays on nickel foam(DL-Co3O4/NF)for water splitting.The unique array-like structure,crystallinity,porosity,and chemical states have been carefully investigated through SEM,TEM,XRD,BET,and XPS techniques.The designated DL-Co3O4/NF has oxygen defects of up to 67.7%and a large BET surface area(57.4 m2g-1).Electrochemical studies show that the catalyst only requires an overpotential of 256 mV to reach 20 mA cm-2,as well as a small Tafel slope of 60.8 mV dec-1,which is far better than all control catalysts.Besides,the catalyst also demonstrates excellent overall water splitting performance in a two-electrode system and good long-term stability,far superior to most previously reported catalysts.Electrocatalytic mechanisms indicate that abundant oxygen vacancies provide more active sites and good conductivity.At the same time,the unique porous arrays facilitate electrolyte transport and gas emissions,thereby synergistically improving OER catalytic performance.
基金financially supported by the National Key R&D Program of China(No.2022YFB4002201)the National Natural Science Foundation of China(Nos.52072362 and 52302119)+3 种基金Jilin Province Science and Technology Development Plan Funding Project(Nos.SKL202302039 and 20220201112GX)Jiangsu Province Innovation Support Program(No.BE2023092-2)Youth Innovation Promotion Association CAS(No.2021223)Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(No.RERU2022008)。
文摘Perovskite oxides with diverse composition and structure have exhibited grand advances in boosting the oxygen reduction and evolution reaction(ORR/OER),which are essential for the reversible protonic ceramic electrochemical cell(R-PCEC)toward the sustainable hydrogen production and utilization.However,enhancement of their activity and stability remains challenging.Herein,we develop the Ta-regulated BaCo_(0.7)Fe_(0.3)O_(3-δ)perovskite oxygen electrode(Ba(Co_(0.7)Fe_(0.3))_(1-x)Ta_xO_(3-δ))with abundant oxygen defects and achieve the simultaneous enhancement in the electrocatalytic activity and stability toward ORR and OER.As-fabricated R-PCEC with(Ba(Co_(0.7)Fe_(0.3))_(0.9)Ta_(0.1)O_(3-δ))(BCFT10)oxygen electrode performs high power density of 1.47 W·cm^(-2)at 650℃in fuel cell mode,and the current density is up to-2.11 A·cm^(-2)at 1.4 V at 650℃in electrolysis mode,as well as the good stability in both the fuel cell and electrolysis modes.Importantly,the cell also demonstrates a stable cycling operation between fuel cell and electrolysis mode,suggesting a great potential of BCFT10 as oxygen electrode material for R-PCECs.
基金This study was financially supported by the National Natural Science Foundation of China(No.22165028)the Nature Science Foundation of Gansu Province(No.20JR10RA108).
文摘Aqueous zinc-ion batteries(AZIBs)have attracted widespread attention due to the advantages of high safety and environmental friendliness.Although V_(2)O_(3) is a promising cathode,the strong electrostatic interaction between Zn^(2+) and V_(2)O_(3) crystal,and the sluggish reaction kinetics still limit their application in AZIBs.Herein,the oxygen defects rich V_(2)O_(3) with conducive poly(3,4-ethylenedioxythiophene)(PEDOT)shell(V_(2)O_(3)-Od@PEDOT)was fabricated for AZIBs by combining the sulfur-assisted thermal reduction and in-situ polymerization method.The introduced oxygen vacancies of V_(2)O_(3)–Od@PEDOT weaken the electrostatic interaction between Zn^(2+) and the host material,improving the interfacial electron transport,while the PEDOT coating enhances the structural stability and conductivity of V_(2)O_(3),thus accelerating the reaction kinetics.Based on the advantages,V_(2)O_(3)–Od@PEDOT electrode delivers a reversible capacity of 495 mAh·g^(−1) at 0.1 A·g^(−1),good rate capability(189 mAh·g^(−1)at 8.0 A·g^(−1)),and an impressive cycling stability with 90.1%capacity retention over 1000 cycles at 8.0 A·g^(−1).The strategy may provide a path for exploiting the other materials for high performance AZIBs.
基金supported by the National Nature Science Foundation of China(11575025,U1832176)the Science and Technology Project of Beijing(Z171100002017008)the Fundamental Research Funds for the Central Universities。
文摘Defect engineering is in the limelight for the fabrication of electrochemical energy storage devices.However,determining the influence of the defect density and location on the electrochemical behavior remains challenging.Herein,self-organized TiO_(2)nanotube arrays(TNTAs)are synthesized by anodization,and their oxygen defect location and density are tuned by a controllable post-annealing process.TNTAs annealed at 600℃ in N2 exhibit the highest capacity(289.2 m Ah g^(-1)at 0.8 C)for lithium-ion storage,while those annealed at 900℃ in N2 show a specific capacitance of 35.6 m F cm^(-2)and stability above96%after 10,000 cycles for supercapacitor.Ex situ electron paramagnetic resonance spectra show that the surface-exposed oxygen defects increase,but the bulk embedded oxygen defects decrease with increasing annealing temperature.Density functional theory simulations reveal that a higher density of bulk oxygen defects corresponds to higher localized electrons states,which upshift the Fermi level and facilitate the lithium intercalation kinetic process.Meanwhile,differential charge density calculation indicates that the increase of surface oxygen defects in the anatase(101)plane leads to higher density excess electrons,which act as negative charge centers to enhance the surface potential for ion adsorption.This oxygen-deficient location and density tunable strategy introduce new opportunities for high-energy and high-power-density energy storage systems.
基金supported by the National Natural Science Foundation of China(No.52002122)the Science and Technology Department of Hubei Province(No.2019AAA038)+1 种基金the Project funded by China Postdoctoral Science Foundation(No.2021M690947)the Wuhan Yellow Crane Talent Program(No.2017-02).
文摘The alkaline zinc-based batteries with high energy density are becoming a research hotspot.However,the poor cycle stability and low-rate performance limit their wide application.Herein,ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays(Od-CNO@Ni NTs)is used as a positive material for rechargeable alkaline Ni–Zn batteries.As the highly uniform Ni nanotube arrays provide a fast electron/ion transport path and abundant active sites,the Od-CNO@Ni NTs electrode delivers excellent capacity(432.7 mAh g^(−1))and rate capability(218.3 mAh g^(−1)at 60 A g^(−1)).Moreover,our Od-CNO@Ni NTs//Zn battery is capable of an ultra-long lifespan(93.0%of initial capacity after 5000 cycles),extremely high energy density of 547.5 Wh kg^(−1)and power density of 92.9 kW kg^(−1)(based on the mass of cathode active substance).Meanwhile,the theoretical calculations reveal that the oxygen defects can enhance the interaction between electrode surface and electrolyte ions,contributing to higher capacity.This work opens a reasonable idea for the development of ultra-durable,ultra-fast,and high-energy Ni–Zn battery.
基金Project supported by the National Natural Science Foundation of China(21707066,21677069)。
文摘For CO catalytic oxidation,Cu and Ce species are of great importance,between which the synergistic effect is worth investigating.In this work,CeO_(2)/Cu_(2)O with Cu_(2)O{111}and{100}planes were comparatively explored on CO catalytic oxidation to reveal the effects of interfacial electronic interactions and oxygen defects.The activity result demonstrates that CeO_(2)/o-Cu_(2)O{111}has superior performance compared with CeO_(2)/c-Cu_(2)O{100}.Credit to the coordination unsaturated copper atoms(Cu_(CUS))on oCu_(2)O{111}surface,the interfacial electronic interactions on CeO_(2)/o-Cu_(2)O{111}are more obvious than those on CeO_(2)/c-Cu_(2)O{100},leading to richer oxygen defect generation,better redox and activation abilities of CO and O_(2)reactants.Furthermore,the reaction mechanism of CeO_(2)/o-Cu_(2)O{111}on CO oxidation is revealed,i.e.,CO and O_(2)are adsorbed on the Cucus on Cu_(2)O{111}and oxygen defect of CeO_(2),respectively,and then synergistically promote the CO oxidation to CO_(2).The work sheds light on the designing optimized ceria and copper-based catalysts and the mechanism of CO oxidation.
基金This work was supported by the Natural Science Foundation of China(51962032,61704114,and 51764049)the Youth Innovative Talents Cultivation Fund,Shihezi University(KX01480109)the Opening Project of The Research Center for Material Chemical Engineering Technology of Xinjiang Bingtuan(2017BTRC007).
文摘The rational design of oxygen vacancies and electronic microstructures of electrode materials for energy storage devices still remains a challenge. Herein, we synthesize nickel cobalt-based oxides nanoflower arrays assembled with nanowires grown on Ni foam via the hydrothermal process followed annealing process in air and argon atmospheres respectively. It is found that the annealing atmosphere has a vital influence on the oxygen vacancies and electronic microstructures of resulting NiCo_(2)O_(4) (NCO-Air) and CoNiO_(2) (NCO-Ar) products, which NCO-Ar has more oxygen vacancies and larger specific surface area of 163.48 m^(2)/g. The density functional theory calculation reveals that more oxygen vacancies can provide more electrons to adsorb –OH free anions resulting in superior electrochemical energy storage performance. Therefore, the assembled asymmetric supercapacitor of NCO-Ar//active carbon delivers an excellent energy density of 112.52 Wh/kg at a power density of 558.73 W/kg and the fabricated NCO-Ar//Zn battery presents the specific capacity of 180.20 mAh/g and energy density of 308.14 Wh/kg. The experimental measurement and theoretical calculation not only provide a facile strategy to construct flower-like mesoporous architectures with massive oxygen vacancies, but also demonstrate that NCO-Ar is an ideal electrode material for the next generation of energy storage devices.
