Among various advanced oxidation processes(AOPs),heterogeneous catalytic ozonation has garnered extensive attention in wastewater treatment owing to its broad pH range applicability and the elimination of the need for...Among various advanced oxidation processes(AOPs),heterogeneous catalytic ozonation has garnered extensive attention in wastewater treatment owing to its broad pH range applicability and the elimination of the need for additional energy input.Enhancing catalyst activity by introducing oxygen vacancies has been used extensively in heterogeneous catalytic ozonation.This paper reviews prevalent methods for the construction and characterization of oxygen vacancies.Based on a thorough examination of existing research,the role of oxygen vacancies is categorized according to their primary mechanisms of action in heterogeneous catalytic ozonation.For example,modulation of the catalyst electronic structure to enhance electron transfer;participation in the reaction as an active site to generate radicals and non-radicals;and exposure of more metal sites to enhance the reaction.Lastly,the paper delineates the limitations and future research directions concerning the role of oxygen vacancies in catalytic ozonation.This review addresses the gap in existing literature concerning the role of oxygen vacancies in catalytic ozone systems,establishes a comprehensive theoretical framework to aid in the design of efficient ozone catalysts,and delves into the functionality of oxygen vacancies in heterogeneous catalytic ozone reactions.展开更多
NaCu_(0.2)Fe_(0.3)Mn_(0.5)O_(2) (NCFM) cathode material was synthesized using a simple solid-state reaction, and the effect of calcination temperature on its interlayer spacing and oxygen vacancies concentration was i...NaCu_(0.2)Fe_(0.3)Mn_(0.5)O_(2) (NCFM) cathode material was synthesized using a simple solid-state reaction, and the effect of calcination temperature on its interlayer spacing and oxygen vacancies concentration was investigated. Through electrochemical testing and material characterizations, higher calcination temperatures increase the electrostatic repulsion between oxygen atoms in adjacent layers, resulting in an expansion of Na layer spacing. This structural change enhances the diffusion kinetics of Na^(+), thereby significantly improving the rate performance of NCFM. Furthermore, elevated calcination temperatures facilitate the reduction of oxygen vacancies, leading to improved crystallinity. This enhancement in crystallinity mitigates structural strain during phase transitions, contributing to improved cyclic stability. Consequently, the optimized NCFM shows an initial discharge specific capacity of 143.3 mA·h/g at 0.1C, with a capacity retention rate of 79.28% after 100 cycles at 1C.展开更多
Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their ...Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.展开更多
4-Nitrophenol(4-NP),a toxic and persistent pollutant in chemical wastewater,presents significant challenges in degradation and mineralization.Conventional ozone oxidation catalysts are hindered by low efficiency,mass ...4-Nitrophenol(4-NP),a toxic and persistent pollutant in chemical wastewater,presents significant challenges in degradation and mineralization.Conventional ozone oxidation catalysts are hindered by low efficiency,mass transfer constraints and metal leaching,necessitating the development of stable and efficient catalysts.Herein,BCn-H/MS,the derivative of Bi(Ce)-MOF,was prepared by in situ incorporation,thermal decomposition and acid etching.The resulting materials were characterized and employed in catalytic ozonation for the reduction of 4-NP.Under the specific experimental conditions of the O_(3)+BC0.3-H/MS system,the total organic carbon(TOC)and chemical oxygen demand(COD)removal rates of 4-NP were observed to reach 94.6%and 91.8%within 30 min,respectively.These two parameters were improved by raising the initial pH,reducing the pollutant concentration and increasing the catalyst dosage.The abundant oxygen vacancies(OVs)were regarded as the pivotal catalytic site of BC0.3-H/MS,which was conducive to the adsorption of O_(3) and the acceleration of the formation of reactive oxygen species(ROS).The regular hollow square structure effectively boosted the specific surface area,increased OVs exposure and accelerated the adsorption and mass transfer process.The electron paramagnetic resonance(EPR)results demonstrated that the primary ROS engaged in the degradation reaction were⋅OH and⋅O_(2)−.BC0.3-H/MS demonstrated excellent stability and reusability in cyclic experiments.Toxicity analysis revealed that the O_(3)+BC0.3-H/MS system exhibited an effective detoxification effect.Ultimately,the primary degradation pathway of 4-NP was proposed through liquid chromatography-mass spectroscopy(LC-MS)and in-situ diffuse reflectance infrared fourier-transform spectroscopy(DRIFTS)analyses at varying reaction times.展开更多
La-BiO_(2-x)composite photocatalyst was successfully synthesized through a single-step hydrothermal strategy.The introduction of La3+into the BiO_(2-x)lattice replaces the Bi^(3+)in the BiO_(2-x)lattice,resulting in a...La-BiO_(2-x)composite photocatalyst was successfully synthesized through a single-step hydrothermal strategy.The introduction of La3+into the BiO_(2-x)lattice replaces the Bi^(3+)in the BiO_(2-x)lattice,resulting in a new defect level and oxygen vacancies(Vo)generation.The·O_(2)^(−)generated in the surface of Vo,which was converted into singlet oxygen(1O2)with the transformation of Bi^(5+)to Bi^(3+).Upon visible(near-infrared)light irradiation,the removal rates of tetracycline(TC),oxytetracycline(OTC),and levofloxacin(LEV)by trace 5%La-BiO_(2-x)(0.1 g/L)reached 84.18%(55.56%),78.85%and 70.12%,respectively.The Toxicity Estimation Software Tool(T.E.S.T)based on Quantitative Structure-Activity Relationship(QSAR)models illustrated that the biological toxicity of TC intermediates can be eliminated by 5%La-BiO_(2-x).The green bean germination rates in 5%La-BiO_(2-x)treated TC solution was close to that in the tap water(100.0%).The inorganic anion and humic acid(HA)exhibited almost no influence on the degradation of TC in lake water and river water.This study enhances the comprehension of biological toxicity elimination in antibiotics degradation process,providing the possibilities for actual applications of La-BiO_(2-x).展开更多
The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of ...The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of active supports,particularly the oxygen vacancy(O_(v)),in modulating C-H bond carboxylation remains unknown.Herein,ultra-small silver clusters and morphologically engineered CeO_(2) support(nanorods,nanocubes,and nano particles)were employed to construct Ag cluster/O_(v) synergistic catalyst,which exhibits variations in Oy concentration by an in situ auto-reduction method.The 0.197%Ag/CeO_(2)-NR catalyst exhibited a high reaction rate for the phenylacetylene carboxylation reaction and the maximal silver utilization efficiency.The characterization and DFT calculations demonstrated that vacancies enhanced CO_(2) adsorption via polarization-induced molecular bending and C-O bond elongation.Positively charged Ag clusters induced by metal-support interactions serve as deprotonation activation centers for alkynes.This synergistic interplay between dual active sites efficiently facilitates the C(sp)-H carboxylation with CO_(2).These findings offer critical insights for the rational selection of active supports in designing efficient C-H carboxylation catalysts.展开更多
Simultaneous integration of rich oxygen vacancies(OVs)and twin crystals in a photocatalyst can not only significantly enhance the near-infrared(NIR)light response but also greatly improve the photocharge separation an...Simultaneous integration of rich oxygen vacancies(OVs)and twin crystals in a photocatalyst can not only significantly enhance the near-infrared(NIR)light response but also greatly improve the photocharge separation and transfer efficiency owing to the induced high electrical conductivity and strong built-in electric field.However,thus far,there has been a lack of a model catalyst containing both twin crystals and OVs.Herein,we develop a simple wet chemical strategy for synthesizing of unprecedented NIR light-responsive OVs-rich Cu_(2)O black nanoparticles with high-density of twin crystals(denoted as black twinned Cu_(2)O).As expected,the black twinned Cu_(2)O exhibits higher visible-NIR and NIR light-driven photodegradation of tetracycline(TC)solution than the counterparts.Significantly,the mechanism insight into twin-dependent photocatalysis in NIR light-responsive Cu_(2)O black nanocrystals with rich OVs is uncovered in depth by density functional theory(DFT)calculations and a series of experimental evidence.Expectantly,this work would be beneficial for the scientific researchers currently focusing on the NIR light-responsive photocatalysis and twin engineering of photocatalysts.展开更多
The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst&...The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst's ability to adsorb and activate N_(2)and H_(2)O,while the ultrathin structure with maximized active crystal facets can maximize the enrichment of effective photogenerated electrons.This work employs a two-step synergistic method to fabricate ultrathin BiVO_(4)with oxygen vacancies and bismuth vacancies(2D-V_(Bi+O)-BVO,thickness<20 nm)for photocatalytic nitrogen reduction.Scanning electron microscopy,transmission electron microscopy(TEM),and atomic force microscopy characterization confirm the transformation of BiVO_(4)from bulk material(bulk-BVO,~1300 nm)to an ultrathin structure(~15 nm).TEM,X-ray photoelectron spectroscopy,electron paramagnetic resonance characterizations,and density functional theory(DFT)calculations verify the construction of oxygen and bismuth vacancies in the ultrathin BiVO_(4).Compared to bulk-BVO,the photocatalytic nitrogen fixation efficiency of 2D-V_(Bi+O)-BVO is increased by 4.7 times,with the highest activity reaching 158.73μmol·g^(-1)·h^(-1).N_(2)-temperature programmed desorption and DFT calculations demonstrate that the oxygen and bismuth vacancies in BiVO_(4),respectively,promote the adsorption/activation of N_(2)and H_(2)O,which is crucial for the overall nitrogen reduction reaction.Photo-deposition experiments prove that the(040)plane is the active surface for electrons.And the ultrathin structure maximizes the(040)facet of BiVO_(4),which is conducive to the high enrichment of electrons.Meanwhile,more active sites can be exposed for the activation of N_(2)and H_(2)O.In situ infrared spectroscopy confirms that N_(2)can be effectively adsorbed onto 2D-V_(Bi+O)-BVO,and the presence of NH_(2)-NH_(2)active species is consistent with the alternating reaction pathway.This study provides new insights into the development of green and efficient photocatalysts with dual vacancies and ultrathin structures.展开更多
Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish ...Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.展开更多
With the ongoing depletion of fossil fuels,energy and environmental issues have become increasingly critical,necessitating the search for effective solutions.Catalysis,being one of the hallmarks of modern industry,off...With the ongoing depletion of fossil fuels,energy and environmental issues have become increasingly critical,necessitating the search for effective solutions.Catalysis,being one of the hallmarks of modern industry,offers a promising avenue for researchers.However,the question of how to significantly enhance the performance of catalysts has gradually drawn the attention of scholars.Defect engineering,a commonly employed and effective approach to improve catalyst activity,has become a significant research focus in the catalysis field in recent years.Nonmetal vacancies have received extensive attention due to their simple form.Consequently,exploration of metal vacancies has remained stagnant for a considerable period,resulting in a scarcity of comprehensive reviews on this topic.Therefore,based on the latest research findings,this paper summarizes and consolidates the construction strategies for metal vacancies,characterization techniques,and their roles in typical energy and environmental catalytic reactions.Additionally,it outlines potential challenges in the future,aiming to provide valuable references for researchers interested in investigating metal vacancies.展开更多
Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for...Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for further investigation,and the specifically exposed crystal faces of CeO_(2)may have an impact on the performance of nitrogen doped CeO_(2).Herein,nitrogen-doped CeO_(2)with different morphologies and exposed crystal faces was prepared,and its performances in the photocatalytic degradation of tetracycline(TC)or hydrogen production via water splitting were evaluated.Density functional theory(DFT)was used to simulate the band structures,density of states,and oxygen defect properties of different CeO_(2)structures.It was found that nitrogen doping and OVs synergistically promoted the catalytic activity of nitrogen-doped CeO_(2).In addition,the exposed crystal faces of CeO_(2)have significant effects on the introduction of nitrogen and the ease of OV generation,as well as the synergistic effect of nitrogen doping with OVs.Among them,the rod-like nitrogen-doped CeO_(2)with exposed(110)face(R-CeO_(2)-NH_(3))showed a photocatalytic degradation ratio of 73.59%for TC and hydrogen production of 156.89μmol/g,outperforming other prepared photocatalysts.展开更多
The development of kinetics-favorable and interfacial-stabilizing electrode materials is critical for temperature-tolerant energy conversion and storage devices,yet remains insufficiently explored.In this study,we pre...The development of kinetics-favorable and interfacial-stabilizing electrode materials is critical for temperature-tolerant energy conversion and storage devices,yet remains insufficiently explored.In this study,we present cation vacancy-rich Ge_(2)Sb_(2)Te_(5)semimetal as an anode material for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs).Ge_(2)Sb_(2)Te_(5)demonstrates exceptional electrochemical performance compared to other metal tellurides and exhibits impressive kinetics and interface stability at low tem-peratures.Experimental results indicate that the synergistic interactions between germanium/antimony vacancies and tellurium atoms,along with accelerated kinetics,enhanced electrical conductivity,and sta-bilized interfacial properties of Ge_(2)Sb_(2)Te_(5),significantly contribute to its improved electrochemical activ-ity.This material enables the LIBs and SIBs that operate effectively at low temperatures,achieving high discharge capacities of 287 and 161 mAh g^(-1) for half-cells at−40℃,and an impressive energy density of 278 and 149 Wh kg^(-1) for full cells at−20℃,respectively.This study provides valuable insights into kinetic activity and interfacial-stabilized electrochemical reactions,thereby facilitating the application of LIBs and SIBs in harsh environments.展开更多
Conventional monometallic sulfides are usually conversion or conversionalloying-dominated anodes,while the sluggish kinetics and severe volume variation greatly hamper their electrochemical properties in sodium-ion ba...Conventional monometallic sulfides are usually conversion or conversionalloying-dominated anodes,while the sluggish kinetics and severe volume variation greatly hamper their electrochemical properties in sodium-ion batteries.Herein,bimetallic sulfides(Vs-ZnIn_(2)S_(4))are developed with S vacancies,which are verified via electron paramagnetic resonance.A possible reaction mechanism(intercalation-conversion-alloying)is proposed,which is characterized by in situ X-ray diffraction.In addition,the small volume change during(de)sodiation of Vs-ZnIn_(2)S_(4)is also observed by in situ transmission electron microscopy.The Vs-ZnIn_(2)S_(4)anode shows ultrastable and superfast sodium storage performance,such as outstanding long-term cycling durability at 10 A g^(-1)(349.6 mAh g^(-1)after 2000 cycles)and rate property at 80 A g^(-1)(222.7 mAh g^(-1)).Moreover,the full cell[Vs-ZnIn_(2)S_(4)//Na_(3)V_(2)(PO_(4))_(3)/C]achieves an excellent property after 300 cycles(185.9 mAh g^(-1))at 5Ag^(-1),showing significant potential for real-world applications.展开更多
Electrocatalytic water splitting for hydrogen production is a key approach to tackling the current energy crisis.Among the catalysts,the traditional Pd@C catalysts are remarkable for their efficiency in hydrogen evolu...Electrocatalytic water splitting for hydrogen production is a key approach to tackling the current energy crisis.Among the catalysts,the traditional Pd@C catalysts are remarkable for their efficiency in hydrogen evolution.However,the high cost and scarcity of Pd catalysts,as well as the instability caused by the corrosiveness of carbon-based substrates,hinder their large-scale application.To overcome this challenge,an effective strategy is to construct highly dispersed Pd single atoms to improve palladium utilization and choose more stable materials as supports.In this study,TiO_(2-x)carriers with abundant oxygen vacancies were prepared and loaded with Pd by photoreduction deposition.Adjusting the palladium content resulted in three forms of Pd-loaded TiO_(2-x):nanoparticles(Pd@TiO_(2-x)(6%,10%)),nanoclusters(Pd@TiO_(2-x)(3%))and single atoms(Pd@TiO_(2-x)(1.5%)).The oxygen vacancies improved the stability of the titanium dioxide materials by providing more active hydrogen adsorption sites and increasing the affinity of Pd for active hydrogen.Single atom loading increased the frequency of oxygen holes in the support and the high activity of monatomic Pd promoted the adsorption of active hydrogen and facilitated the formation of active hydrogen intermediates.The synergistic effect of single atoms and oxygen vacancies improved the stability and catalytic activity of the composite material.Pd@TiO_(2-x)(1.5%)showed outstanding performance in hydrogen evolution in an acidic medium with an overpotential of only 24 m V at a current density of 10 m A/cm^(2)and a low Tafel rise of 41.9 m V/dec.This study provides an effective strategy for the development of high-performance hydrogen evolution(HER)catalysts.展开更多
1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are...1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are generally categorized into homogeneous and heterogeneous nucleation.Homogeneous nucleation relies on structural and energy fluctuations within the solution to generate the driving force necessary for direct nucleation.展开更多
Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at h...Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at high voltage.The successful implementation of LRMO in energy storage systems is contingent upon the enhancement of their rate capabilities.However,the underlying relationship between high-rate cycling and electrode degradation for LRMO,particularly concerning structural evolution,still remains unclear.Benefiting from the high time resolution abilities of liquid-metal-jet operando twodimensional X-ray diffraction,it is observed that the Li_(2)MnO_(3)phase in LRMO is gradually activated accompanied by the emergence of oxygen vacancies during cycling at 1 C(1 C=250 mA/g).Consequently,the crystal lattice flexibility of LRMO is systematically enhanced,thereby preventing the collapse of the bulk structure.While,continuous release of oxygen during extended cycling results in deteriorations of the self-adjusting damping effect of the structure,ultimately leading to a decline in capacity.The findings of this study not only contribute to a more profound understanding of the structural changes of LRMOs at high rates,but also provide novel perspectives for the rational design of LRMOs with superior rate performances.展开更多
In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the p...In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics.Therefore,a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported.A high starting capacity(400 mAh g^(-1))can be achieved by Ov-V2O5,and it is capable of undergoing 200 cycles at 0.4 A g^(-1),with a termination discharge capacity of103 mAh g^(-1).Mechanism analysis demonstrated that metastable structures(AlxV2O5and HxV2O5)were constructed through the insertion of Al^(3+)/H^(+)during discharging,which existed in the lattice intercalation with V2O5.The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency.In addition,the metastable structure allows the electrostatic interaction between Al3+and the main backbone to establish protection and optimize the transport channel.In parallel,this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation,with a view to better understanding the mechanism of the synergistic participation of Al3+and H+in the reaction.This work not only reports a method for cathode materials to modulate oxygen vacancies,but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.展开更多
Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,real...Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,realizing further enhancement of NRR performance.In 0.1 mol/L Na_(2)SO_(4),W_(4)MoO_(3)NWs rich in O vacancies(CTAB-D-W_(4)MoO_(3))achieve a large NH3yield of 60.77μg h^(-1)mg^(-1)cat.at-0.70 V vs.RHE and a high faradaic efficiency of 56.42%at-0.60 V,much superior to the W_(4)MoO_(3)NWs deficient in oxygen vacancies(20.26μg h^(-1)mg^(-1)cat.and 17.1%at-0.70 V vs.RHE).Meanwhile,W_(4)MoO_(3)NWs rich in O-vacancies also show high electrochemical stability.Density functional theory(DFT)calculations present that O vacancies in CTAB-D-W_(4)MoO_(3)reduce the energy barrier formed by the intermediate of^(*)N-NH,facilitate the activation and further hydrogenation of^(*)N-N,promote the NRR process,and improve NRR activity.展开更多
For the effective treatment of the wastewater with low-medium concentration ammonia nitrogen and low strength COD,a high-performance Co_(3)O_(4) catalyst supported on carbon nanocages(CNCs)was prepared.By isovolumetri...For the effective treatment of the wastewater with low-medium concentration ammonia nitrogen and low strength COD,a high-performance Co_(3)O_(4) catalyst supported on carbon nanocages(CNCs)was prepared.By isovolumetric im pregnation,Co_(3)O_(4) could be uniformly dispersed on surface of CNCs,which possess tiny particle size and strong electron transfer capability.The catalytic performance of the prepared Co_(3)O_(4)/CNCs catalysts with different Co_(3)O_(4) loadings was systematically evaluated and compared with Co_(3)O_(4)/CNTs.It is found that 20 wt.%Co_(3)O_(4)/CNCs shows the best catalytic performance,achieving an ammonia nitrogen conversion rate of 71.0%and a nitrogen selectivity of 81.8%.Compared to commonly used Co_(3)O_(4),ammonia conversion and nitrogen selectivity of Co_(3)O_(4)/CNCs increased by 28.9%and 15.8%respectively.In the five consecutive cycles,the catalytic activity remained stable.The mechanism that CNCs support effectively increases the surface oxygen vacancies of Co_(3)O_(4) through XPS analysis was also elucidated,and DFT calculations confirm strong electron transfer between CNCs and Co_(3)O_(4),rendering Co_(3)O_(4) nanoparticles as the primary catalytic active sites.The results may contribute to the development of highperformance catalytic ozone oxidation catalysts for ammonia nitrogen.展开更多
The titanium-based ion sieve H2TiO_(3)(HTO)is recognized for its high lithium adsorption capacity and exceptional structural stability,making it a leading candidate for lithium extraction from aqueous resources.In thi...The titanium-based ion sieve H2TiO_(3)(HTO)is recognized for its high lithium adsorption capacity and exceptional structural stability,making it a leading candidate for lithium extraction from aqueous resources.In this study,chromium-doped H2TiO_(3)(HCTO)was synthesized via a high-temperature solid-state method to enhance lithium adsorption performance.A series of characterization techniques were employed to analyze HCTO's structure,morphology,specific surface area,and valence state evolution.Static adsorption experiments were performed to evaluate HCTO's adsorption performance and elucidate its mechanism.Experimental results and density functional theory(DFT)calculations demonstrate that Cr^(3+)doping induces oxygen vacancies(Ovs)formation in the HTO lattice,reduces Li^(+)diffusion barriers in the solid phase,enhances electron transport efficiency,and strengthens electrostatic Li^(+)-adsorbent interactions,collectively improving Li^(+)adsorption performance.Cr^(3+)incorporation effectively mitigates particle agglomeration,resulting in HCTO's specific surface area reaching 46.04 m2g^(-1).Additionally,the crystal defects induced by Cr^(3+)doping create a"pinning effect",thereby enhancing the structural stability of the adsorbent material.Experimental data demonstrate that HCTO-1%achieves a Li^(+)adsorption capacity of 48.07 mg g^(-1)in lithium-containing solutions,representing a 61.58%enhancement compared to unmodified HTO.After five adsorptionDdesorption cycles,the Ti^(4+)dissolution rate in HCTO-1%remained below 0.20%,demonstrating excellent cycling stability.In salt lake brine,HCTO-1%exhibits high Li^(+)selectivity over competing cations.Mechanistic studies reveal that the adsorption process of Li^(+)on HCTO-1%follows an ion exchange mechanism,involving the breaking of ODH bonds and the formation of ODLi bonds.展开更多
基金support from the Key R&D Program of Zhejiang province(No.2024C03136).
文摘Among various advanced oxidation processes(AOPs),heterogeneous catalytic ozonation has garnered extensive attention in wastewater treatment owing to its broad pH range applicability and the elimination of the need for additional energy input.Enhancing catalyst activity by introducing oxygen vacancies has been used extensively in heterogeneous catalytic ozonation.This paper reviews prevalent methods for the construction and characterization of oxygen vacancies.Based on a thorough examination of existing research,the role of oxygen vacancies is categorized according to their primary mechanisms of action in heterogeneous catalytic ozonation.For example,modulation of the catalyst electronic structure to enhance electron transfer;participation in the reaction as an active site to generate radicals and non-radicals;and exposure of more metal sites to enhance the reaction.Lastly,the paper delineates the limitations and future research directions concerning the role of oxygen vacancies in catalytic ozonation.This review addresses the gap in existing literature concerning the role of oxygen vacancies in catalytic ozone systems,establishes a comprehensive theoretical framework to aid in the design of efficient ozone catalysts,and delves into the functionality of oxygen vacancies in heterogeneous catalytic ozone reactions.
基金supported by the National Natural Science Foundation of China(No.12175089)the Key Research and Development Program of Yunnan Province,China(No.202103AF140006)+2 种基金Basic Research Programs of Yunnan Provincial Science and Technology Department,China(Nos.202001AW070004,202301AS070051,202401AV070008)Yunnan Industrial Innovative Talents Program for“Xingdian Talent Support Plan”,China(No.KKXY202252001)Yunnan Major Scientific and Technological Projects,China(No.202202AG050003)。
文摘NaCu_(0.2)Fe_(0.3)Mn_(0.5)O_(2) (NCFM) cathode material was synthesized using a simple solid-state reaction, and the effect of calcination temperature on its interlayer spacing and oxygen vacancies concentration was investigated. Through electrochemical testing and material characterizations, higher calcination temperatures increase the electrostatic repulsion between oxygen atoms in adjacent layers, resulting in an expansion of Na layer spacing. This structural change enhances the diffusion kinetics of Na^(+), thereby significantly improving the rate performance of NCFM. Furthermore, elevated calcination temperatures facilitate the reduction of oxygen vacancies, leading to improved crystallinity. This enhancement in crystallinity mitigates structural strain during phase transitions, contributing to improved cyclic stability. Consequently, the optimized NCFM shows an initial discharge specific capacity of 143.3 mA·h/g at 0.1C, with a capacity retention rate of 79.28% after 100 cycles at 1C.
基金supported by the National Natural Science Foundation of China (Grant Nos.12334001,52461160301,52322311,52427802,12222414)the National Key R&D Program of China (Grant Nos.2024YFA1208201,2021YFA1400500,2021YFA1400204)the Youth Innovation Promotion Association of the CAS (Grant Nos.Y2022003 and 2020009)。
文摘Hafnia-based ferroelectrics have emerged as promising materials for next-generation nanoelectronics owing to their robust nanoscale properties and compatibility with metal-oxide-semiconductor technology.However,their metastable nature remains a key challenge for practical implementation.Utilizing scanning transmission electron microscopy,we investigated the atomic-scale mechanisms governing ferroelectric transitions and the metastability of polar phases in 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)thin films.Our results demonstrate that oxygen vacancies,coupled with rhombohedral distortions of the cation lattice,facilitate ferroelectric phase transitions and enable robust polar switching through adaptive processes,including cell-by-cell oxygen displacement and domain-wall-mediated nucleation and growth.These findings underscore the pivotal role of oxygen vacancies and lattice distortions in stabilizing polar phases and provide detailed insights into the atomic structures and transition dynamics of polymorphic Hf_(0.5)Zr_(0.5)O_(2-x),thereby advancing its potential for practical device applications.
基金supported by the National Natural Science Foundation of China(Regional Fund)(No.51868054)the Natural Science Foundation of Inner Mongolia of China(General Program)(No.2022MS05052).
文摘4-Nitrophenol(4-NP),a toxic and persistent pollutant in chemical wastewater,presents significant challenges in degradation and mineralization.Conventional ozone oxidation catalysts are hindered by low efficiency,mass transfer constraints and metal leaching,necessitating the development of stable and efficient catalysts.Herein,BCn-H/MS,the derivative of Bi(Ce)-MOF,was prepared by in situ incorporation,thermal decomposition and acid etching.The resulting materials were characterized and employed in catalytic ozonation for the reduction of 4-NP.Under the specific experimental conditions of the O_(3)+BC0.3-H/MS system,the total organic carbon(TOC)and chemical oxygen demand(COD)removal rates of 4-NP were observed to reach 94.6%and 91.8%within 30 min,respectively.These two parameters were improved by raising the initial pH,reducing the pollutant concentration and increasing the catalyst dosage.The abundant oxygen vacancies(OVs)were regarded as the pivotal catalytic site of BC0.3-H/MS,which was conducive to the adsorption of O_(3) and the acceleration of the formation of reactive oxygen species(ROS).The regular hollow square structure effectively boosted the specific surface area,increased OVs exposure and accelerated the adsorption and mass transfer process.The electron paramagnetic resonance(EPR)results demonstrated that the primary ROS engaged in the degradation reaction were⋅OH and⋅O_(2)−.BC0.3-H/MS demonstrated excellent stability and reusability in cyclic experiments.Toxicity analysis revealed that the O_(3)+BC0.3-H/MS system exhibited an effective detoxification effect.Ultimately,the primary degradation pathway of 4-NP was proposed through liquid chromatography-mass spectroscopy(LC-MS)and in-situ diffuse reflectance infrared fourier-transform spectroscopy(DRIFTS)analyses at varying reaction times.
基金supported by Hunan Provincial Natural Science Foundation of China(Nos.2022JJ40505 and 2024JJ8069)the National Natural Science Foundation of China(No.21671026)The authors would like to extend their appreciation to Researchers Supporting Project number(RSP-2025-R20),King Saud University,Riyadh,Saudi Arabia.
文摘La-BiO_(2-x)composite photocatalyst was successfully synthesized through a single-step hydrothermal strategy.The introduction of La3+into the BiO_(2-x)lattice replaces the Bi^(3+)in the BiO_(2-x)lattice,resulting in a new defect level and oxygen vacancies(Vo)generation.The·O_(2)^(−)generated in the surface of Vo,which was converted into singlet oxygen(1O2)with the transformation of Bi^(5+)to Bi^(3+).Upon visible(near-infrared)light irradiation,the removal rates of tetracycline(TC),oxytetracycline(OTC),and levofloxacin(LEV)by trace 5%La-BiO_(2-x)(0.1 g/L)reached 84.18%(55.56%),78.85%and 70.12%,respectively.The Toxicity Estimation Software Tool(T.E.S.T)based on Quantitative Structure-Activity Relationship(QSAR)models illustrated that the biological toxicity of TC intermediates can be eliminated by 5%La-BiO_(2-x).The green bean germination rates in 5%La-BiO_(2-x)treated TC solution was close to that in the tap water(100.0%).The inorganic anion and humic acid(HA)exhibited almost no influence on the degradation of TC in lake water and river water.This study enhances the comprehension of biological toxicity elimination in antibiotics degradation process,providing the possibilities for actual applications of La-BiO_(2-x).
基金financially supported by the National Natural Science Foundation of China(22102194)the Science and Technology Plan of Gansu Province(24JRRA067,23ZDFA016)the Youth Innovation Promotion Association of CAS(2022427)。
文摘The carboxylation of alkynes with CO_(2) has attracted considerable interest due to the valorization of C1resources and atomic economy.Much effort focused on active metals(e.g.,Au,Ag,Cu),while the mechanistic role of active supports,particularly the oxygen vacancy(O_(v)),in modulating C-H bond carboxylation remains unknown.Herein,ultra-small silver clusters and morphologically engineered CeO_(2) support(nanorods,nanocubes,and nano particles)were employed to construct Ag cluster/O_(v) synergistic catalyst,which exhibits variations in Oy concentration by an in situ auto-reduction method.The 0.197%Ag/CeO_(2)-NR catalyst exhibited a high reaction rate for the phenylacetylene carboxylation reaction and the maximal silver utilization efficiency.The characterization and DFT calculations demonstrated that vacancies enhanced CO_(2) adsorption via polarization-induced molecular bending and C-O bond elongation.Positively charged Ag clusters induced by metal-support interactions serve as deprotonation activation centers for alkynes.This synergistic interplay between dual active sites efficiently facilitates the C(sp)-H carboxylation with CO_(2).These findings offer critical insights for the rational selection of active supports in designing efficient C-H carboxylation catalysts.
基金supported by the National Natural Science Foundation of China(NSFC Nos.52271228,52127802,52201279,52301288,52202298,and 22208262)the Natural Science Foundation of Shaanxi Province(No.2023-JC-ZD-21)+1 种基金the Key Research and Development Plan of Shaanxi Province(No.2023GXLH-046)the Science and Technology Project of Xi'an(No.2021SFGX0004)。
文摘Simultaneous integration of rich oxygen vacancies(OVs)and twin crystals in a photocatalyst can not only significantly enhance the near-infrared(NIR)light response but also greatly improve the photocharge separation and transfer efficiency owing to the induced high electrical conductivity and strong built-in electric field.However,thus far,there has been a lack of a model catalyst containing both twin crystals and OVs.Herein,we develop a simple wet chemical strategy for synthesizing of unprecedented NIR light-responsive OVs-rich Cu_(2)O black nanoparticles with high-density of twin crystals(denoted as black twinned Cu_(2)O).As expected,the black twinned Cu_(2)O exhibits higher visible-NIR and NIR light-driven photodegradation of tetracycline(TC)solution than the counterparts.Significantly,the mechanism insight into twin-dependent photocatalysis in NIR light-responsive Cu_(2)O black nanocrystals with rich OVs is uncovered in depth by density functional theory(DFT)calculations and a series of experimental evidence.Expectantly,this work would be beneficial for the scientific researchers currently focusing on the NIR light-responsive photocatalysis and twin engineering of photocatalysts.
文摘The efficient utilization of photogenerated electrons and the effective activation of reactive molecules are among the major challenges in photocatalytic nitrogen reduction.Defect engineering can enhance the catalyst's ability to adsorb and activate N_(2)and H_(2)O,while the ultrathin structure with maximized active crystal facets can maximize the enrichment of effective photogenerated electrons.This work employs a two-step synergistic method to fabricate ultrathin BiVO_(4)with oxygen vacancies and bismuth vacancies(2D-V_(Bi+O)-BVO,thickness<20 nm)for photocatalytic nitrogen reduction.Scanning electron microscopy,transmission electron microscopy(TEM),and atomic force microscopy characterization confirm the transformation of BiVO_(4)from bulk material(bulk-BVO,~1300 nm)to an ultrathin structure(~15 nm).TEM,X-ray photoelectron spectroscopy,electron paramagnetic resonance characterizations,and density functional theory(DFT)calculations verify the construction of oxygen and bismuth vacancies in the ultrathin BiVO_(4).Compared to bulk-BVO,the photocatalytic nitrogen fixation efficiency of 2D-V_(Bi+O)-BVO is increased by 4.7 times,with the highest activity reaching 158.73μmol·g^(-1)·h^(-1).N_(2)-temperature programmed desorption and DFT calculations demonstrate that the oxygen and bismuth vacancies in BiVO_(4),respectively,promote the adsorption/activation of N_(2)and H_(2)O,which is crucial for the overall nitrogen reduction reaction.Photo-deposition experiments prove that the(040)plane is the active surface for electrons.And the ultrathin structure maximizes the(040)facet of BiVO_(4),which is conducive to the high enrichment of electrons.Meanwhile,more active sites can be exposed for the activation of N_(2)and H_(2)O.In situ infrared spectroscopy confirms that N_(2)can be effectively adsorbed onto 2D-V_(Bi+O)-BVO,and the presence of NH_(2)-NH_(2)active species is consistent with the alternating reaction pathway.This study provides new insights into the development of green and efficient photocatalysts with dual vacancies and ultrathin structures.
基金Institute of Technology Research Fund Program for Young Scholars21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde, 352100, China (21C–OP-202314)。
文摘Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.
基金financially supported by National Key R&D Program of China(2021YFB3500702)National Natural Science Foundation of China(Nos.21677010 and 51808037)Special fund of Beijing Key Laboratory of Indoor Air Quality Evaluation and Control(No.BZ0344KF21-04).
文摘With the ongoing depletion of fossil fuels,energy and environmental issues have become increasingly critical,necessitating the search for effective solutions.Catalysis,being one of the hallmarks of modern industry,offers a promising avenue for researchers.However,the question of how to significantly enhance the performance of catalysts has gradually drawn the attention of scholars.Defect engineering,a commonly employed and effective approach to improve catalyst activity,has become a significant research focus in the catalysis field in recent years.Nonmetal vacancies have received extensive attention due to their simple form.Consequently,exploration of metal vacancies has remained stagnant for a considerable period,resulting in a scarcity of comprehensive reviews on this topic.Therefore,based on the latest research findings,this paper summarizes and consolidates the construction strategies for metal vacancies,characterization techniques,and their roles in typical energy and environmental catalytic reactions.Additionally,it outlines potential challenges in the future,aiming to provide valuable references for researchers interested in investigating metal vacancies.
基金Project(52164025)supported by the National Natural Science Foundation of ChinaProject([2020]1Y219)supported by the Basic Research Program from the Science&Technology Department of Guizhou Province,China+2 种基金Project([2019]30)supported by the Training Project from Guizhou University,ChinaProject([2023]04)supported by the Guizhou University Innovation Talent Team Project,ChinaProject([2022]041)supported by the Natural Science Research Project of Guizhou Provincial Department of Education,China。
文摘Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for further investigation,and the specifically exposed crystal faces of CeO_(2)may have an impact on the performance of nitrogen doped CeO_(2).Herein,nitrogen-doped CeO_(2)with different morphologies and exposed crystal faces was prepared,and its performances in the photocatalytic degradation of tetracycline(TC)or hydrogen production via water splitting were evaluated.Density functional theory(DFT)was used to simulate the band structures,density of states,and oxygen defect properties of different CeO_(2)structures.It was found that nitrogen doping and OVs synergistically promoted the catalytic activity of nitrogen-doped CeO_(2).In addition,the exposed crystal faces of CeO_(2)have significant effects on the introduction of nitrogen and the ease of OV generation,as well as the synergistic effect of nitrogen doping with OVs.Among them,the rod-like nitrogen-doped CeO_(2)with exposed(110)face(R-CeO_(2)-NH_(3))showed a photocatalytic degradation ratio of 73.59%for TC and hydrogen production of 156.89μmol/g,outperforming other prepared photocatalysts.
基金financially supported by the Department of Sci-ence and Technology of Jilin Province(No.20240602107RC)support from the National Natural Sci-ence Foundation of China(No.52202237).
文摘The development of kinetics-favorable and interfacial-stabilizing electrode materials is critical for temperature-tolerant energy conversion and storage devices,yet remains insufficiently explored.In this study,we present cation vacancy-rich Ge_(2)Sb_(2)Te_(5)semimetal as an anode material for lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs).Ge_(2)Sb_(2)Te_(5)demonstrates exceptional electrochemical performance compared to other metal tellurides and exhibits impressive kinetics and interface stability at low tem-peratures.Experimental results indicate that the synergistic interactions between germanium/antimony vacancies and tellurium atoms,along with accelerated kinetics,enhanced electrical conductivity,and sta-bilized interfacial properties of Ge_(2)Sb_(2)Te_(5),significantly contribute to its improved electrochemical activ-ity.This material enables the LIBs and SIBs that operate effectively at low temperatures,achieving high discharge capacities of 287 and 161 mAh g^(-1) for half-cells at−40℃,and an impressive energy density of 278 and 149 Wh kg^(-1) for full cells at−20℃,respectively.This study provides valuable insights into kinetic activity and interfacial-stabilized electrochemical reactions,thereby facilitating the application of LIBs and SIBs in harsh environments.
基金Fundamental Research Funds for the Central UniversitiesGraduate Innovation Funds of Jilin University,Grant/Award Number:2022081+1 种基金National Natural Science Foundation of China,Grant/Award Number:52130101Science and Technology Development Program of Jilin Province,Grant/Award Numbers:20230402058GH,20240101128JC。
文摘Conventional monometallic sulfides are usually conversion or conversionalloying-dominated anodes,while the sluggish kinetics and severe volume variation greatly hamper their electrochemical properties in sodium-ion batteries.Herein,bimetallic sulfides(Vs-ZnIn_(2)S_(4))are developed with S vacancies,which are verified via electron paramagnetic resonance.A possible reaction mechanism(intercalation-conversion-alloying)is proposed,which is characterized by in situ X-ray diffraction.In addition,the small volume change during(de)sodiation of Vs-ZnIn_(2)S_(4)is also observed by in situ transmission electron microscopy.The Vs-ZnIn_(2)S_(4)anode shows ultrastable and superfast sodium storage performance,such as outstanding long-term cycling durability at 10 A g^(-1)(349.6 mAh g^(-1)after 2000 cycles)and rate property at 80 A g^(-1)(222.7 mAh g^(-1)).Moreover,the full cell[Vs-ZnIn_(2)S_(4)//Na_(3)V_(2)(PO_(4))_(3)/C]achieves an excellent property after 300 cycles(185.9 mAh g^(-1))at 5Ag^(-1),showing significant potential for real-world applications.
基金supported by the Key Project of Tianjin Natural Science Foundation(No.23JCZDJC00570)Special Funding of China Postdoctoral Science Foundation(No.2023T160268)+3 种基金China Postdoctoral Science Foundation(No.2023M741362)the National natural science foundation of China(Nos.22276209 and 21822608)Research Center for Eco-Environmental Science(No.RCEES-TDZ-2021-7)the support from the Youth Innovation Promotion Association of CAS(No.Y2021019)。
文摘Electrocatalytic water splitting for hydrogen production is a key approach to tackling the current energy crisis.Among the catalysts,the traditional Pd@C catalysts are remarkable for their efficiency in hydrogen evolution.However,the high cost and scarcity of Pd catalysts,as well as the instability caused by the corrosiveness of carbon-based substrates,hinder their large-scale application.To overcome this challenge,an effective strategy is to construct highly dispersed Pd single atoms to improve palladium utilization and choose more stable materials as supports.In this study,TiO_(2-x)carriers with abundant oxygen vacancies were prepared and loaded with Pd by photoreduction deposition.Adjusting the palladium content resulted in three forms of Pd-loaded TiO_(2-x):nanoparticles(Pd@TiO_(2-x)(6%,10%)),nanoclusters(Pd@TiO_(2-x)(3%))and single atoms(Pd@TiO_(2-x)(1.5%)).The oxygen vacancies improved the stability of the titanium dioxide materials by providing more active hydrogen adsorption sites and increasing the affinity of Pd for active hydrogen.Single atom loading increased the frequency of oxygen holes in the support and the high activity of monatomic Pd promoted the adsorption of active hydrogen and facilitated the formation of active hydrogen intermediates.The synergistic effect of single atoms and oxygen vacancies improved the stability and catalytic activity of the composite material.Pd@TiO_(2-x)(1.5%)showed outstanding performance in hydrogen evolution in an acidic medium with an overpotential of only 24 m V at a current density of 10 m A/cm^(2)and a low Tafel rise of 41.9 m V/dec.This study provides an effective strategy for the development of high-performance hydrogen evolution(HER)catalysts.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A20130 and 52475357).
文摘1.Introduction Al-Zn-Mg-Cu alloy is a typical age-hardening aluminum alloy,its strength and toughness are significantly influenced by precipita-tion behavior.The nucleation mechanisms of precipitates in this alloy are generally categorized into homogeneous and heterogeneous nucleation.Homogeneous nucleation relies on structural and energy fluctuations within the solution to generate the driving force necessary for direct nucleation.
基金financial supports from the National Natural Science Foundation of China(52372211,52371225 and 92472115)the Guangdong Province Major Talent Introducing Program(2021QN020687)+1 种基金the Shenzhen Basic Research Foundation(JCYJ20230807112503007)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2020A1515110176)。
文摘Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at high voltage.The successful implementation of LRMO in energy storage systems is contingent upon the enhancement of their rate capabilities.However,the underlying relationship between high-rate cycling and electrode degradation for LRMO,particularly concerning structural evolution,still remains unclear.Benefiting from the high time resolution abilities of liquid-metal-jet operando twodimensional X-ray diffraction,it is observed that the Li_(2)MnO_(3)phase in LRMO is gradually activated accompanied by the emergence of oxygen vacancies during cycling at 1 C(1 C=250 mA/g).Consequently,the crystal lattice flexibility of LRMO is systematically enhanced,thereby preventing the collapse of the bulk structure.While,continuous release of oxygen during extended cycling results in deteriorations of the self-adjusting damping effect of the structure,ultimately leading to a decline in capacity.The findings of this study not only contribute to a more profound understanding of the structural changes of LRMOs at high rates,but also provide novel perspectives for the rational design of LRMOs with superior rate performances.
基金financially supported by the National Natural Science Foundation of China(52102233)Science and Technology Project of Hebei Education Department(QN2023019).
文摘In recent years,aqueous aluminum ion batteries have been widely studied owing to their abundant energy storage and high theo retical capacity.An in-depth study of vanadium oxide materials is necessary to address the precipitation of insoluble products covered cathode surface and the slow reaction kinetics.Therefore,a method using a simple one-step hydrothermal preparation and oxalic acid to regulate oxygen vacancies has been reported.A high starting capacity(400 mAh g^(-1))can be achieved by Ov-V2O5,and it is capable of undergoing 200 cycles at 0.4 A g^(-1),with a termination discharge capacity of103 mAh g^(-1).Mechanism analysis demonstrated that metastable structures(AlxV2O5and HxV2O5)were constructed through the insertion of Al^(3+)/H^(+)during discharging,which existed in the lattice intercalation with V2O5.The incorporation of oxygen vacancies lowers the reaction energy barrier while improving the ion transport efficiency.In addition,the metastable structure allows the electrostatic interaction between Al3+and the main backbone to establish protection and optimize the transport channel.In parallel,this work exploits ex-situ characterization and DFT to obtain a profound insight into the instrumental effect of oxygen vacancies in the construction of metastable structures during in-situ electrochemical activation,with a view to better understanding the mechanism of the synergistic participation of Al3+and H+in the reaction.This work not only reports a method for cathode materials to modulate oxygen vacancies,but also lays the foundation for a deeper understanding of the metastable structure of vanadium oxides.
基金supported by the National Natural Science Foundation of China(No.51872173)Natural Science Foundation of Shandong Province(No.ZR2022JQ21)。
文摘Herein,vacancy engineering is utilized reasonably to explore molybdenum tungsten oxide nanowires(W_(4)MoO_(3)NWs)rich in O-vacancies as an advanced electrochemical nitrogen reduction reaction(eNRR)electrocatalyst,realizing further enhancement of NRR performance.In 0.1 mol/L Na_(2)SO_(4),W_(4)MoO_(3)NWs rich in O vacancies(CTAB-D-W_(4)MoO_(3))achieve a large NH3yield of 60.77μg h^(-1)mg^(-1)cat.at-0.70 V vs.RHE and a high faradaic efficiency of 56.42%at-0.60 V,much superior to the W_(4)MoO_(3)NWs deficient in oxygen vacancies(20.26μg h^(-1)mg^(-1)cat.and 17.1%at-0.70 V vs.RHE).Meanwhile,W_(4)MoO_(3)NWs rich in O-vacancies also show high electrochemical stability.Density functional theory(DFT)calculations present that O vacancies in CTAB-D-W_(4)MoO_(3)reduce the energy barrier formed by the intermediate of^(*)N-NH,facilitate the activation and further hydrogenation of^(*)N-N,promote the NRR process,and improve NRR activity.
基金supported by the National Natural Science Foundation of China(No.22278202).
文摘For the effective treatment of the wastewater with low-medium concentration ammonia nitrogen and low strength COD,a high-performance Co_(3)O_(4) catalyst supported on carbon nanocages(CNCs)was prepared.By isovolumetric im pregnation,Co_(3)O_(4) could be uniformly dispersed on surface of CNCs,which possess tiny particle size and strong electron transfer capability.The catalytic performance of the prepared Co_(3)O_(4)/CNCs catalysts with different Co_(3)O_(4) loadings was systematically evaluated and compared with Co_(3)O_(4)/CNTs.It is found that 20 wt.%Co_(3)O_(4)/CNCs shows the best catalytic performance,achieving an ammonia nitrogen conversion rate of 71.0%and a nitrogen selectivity of 81.8%.Compared to commonly used Co_(3)O_(4),ammonia conversion and nitrogen selectivity of Co_(3)O_(4)/CNCs increased by 28.9%and 15.8%respectively.In the five consecutive cycles,the catalytic activity remained stable.The mechanism that CNCs support effectively increases the surface oxygen vacancies of Co_(3)O_(4) through XPS analysis was also elucidated,and DFT calculations confirm strong electron transfer between CNCs and Co_(3)O_(4),rendering Co_(3)O_(4) nanoparticles as the primary catalytic active sites.The results may contribute to the development of highperformance catalytic ozone oxidation catalysts for ammonia nitrogen.
基金financially supported by Qinghai Provincial Key Research and Development(R&D)and Transformation Program(No.2025-QY-240)Tianjin UniversityQinghai Minzu University Joint Innovation Fund(Nos.24TQ003,2022TQ05,and 2023TQ002)
文摘The titanium-based ion sieve H2TiO_(3)(HTO)is recognized for its high lithium adsorption capacity and exceptional structural stability,making it a leading candidate for lithium extraction from aqueous resources.In this study,chromium-doped H2TiO_(3)(HCTO)was synthesized via a high-temperature solid-state method to enhance lithium adsorption performance.A series of characterization techniques were employed to analyze HCTO's structure,morphology,specific surface area,and valence state evolution.Static adsorption experiments were performed to evaluate HCTO's adsorption performance and elucidate its mechanism.Experimental results and density functional theory(DFT)calculations demonstrate that Cr^(3+)doping induces oxygen vacancies(Ovs)formation in the HTO lattice,reduces Li^(+)diffusion barriers in the solid phase,enhances electron transport efficiency,and strengthens electrostatic Li^(+)-adsorbent interactions,collectively improving Li^(+)adsorption performance.Cr^(3+)incorporation effectively mitigates particle agglomeration,resulting in HCTO's specific surface area reaching 46.04 m2g^(-1).Additionally,the crystal defects induced by Cr^(3+)doping create a"pinning effect",thereby enhancing the structural stability of the adsorbent material.Experimental data demonstrate that HCTO-1%achieves a Li^(+)adsorption capacity of 48.07 mg g^(-1)in lithium-containing solutions,representing a 61.58%enhancement compared to unmodified HTO.After five adsorptionDdesorption cycles,the Ti^(4+)dissolution rate in HCTO-1%remained below 0.20%,demonstrating excellent cycling stability.In salt lake brine,HCTO-1%exhibits high Li^(+)selectivity over competing cations.Mechanistic studies reveal that the adsorption process of Li^(+)on HCTO-1%follows an ion exchange mechanism,involving the breaking of ODH bonds and the formation of ODLi bonds.
