Researchers have recently developed various surface engineering approaches to modify environmental catalysts and improve their catalytic activity.Defect engineering has proved to be one of the most promising modificat...Researchers have recently developed various surface engineering approaches to modify environmental catalysts and improve their catalytic activity.Defect engineering has proved to be one of the most promising modification methods.Constructing defects on the surface of catalytic materials can effectively modulate the coordination environment of the active sites,affecting and changing the electrons,geometry,and other important properties at the catalytic active sites,thus altering the catalytic activity of the catalysts.However,the conformational relationship between defects and catalytic activity remains to be clarified.This dissertation focuses on an overview of recent advances in defect engineering in environmental catalysis.Based on defining the classification of defects in catalytic materials,defect construction methods,and characterization techniques are summarized and discussed.Focusing on an overview of the characteristics of the role of defects in electrocatalytic,photocatalytic,and thermal catalytic reactions and the mechanism of catalytic reactions.An elaborate link is given between the reaction activity and the structure of catalyst defects.Finally,the existing challenges and possible future directions for the application of defect engineering in environmental catalysis are discussed,which are expected to guide the design and development of efficient environmental catalysts and mechanism studies.展开更多
High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,inclu...High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,including high figure of merit(FOM),insulation resistivity(ρ)and depolarization temperature(Td)are indispensable but hard to achieve in lead-free piezoceramics,especially operating at 250°C has not been reported before.Herein,well-balanced performances are achieved in BiFeO3–BaTiO3 ceramics via innovative defect engineering with respect to delicate manganese doping.Due to the synergistic effect of enhancing electrostrictive coefficient by polarization configuration optimization,regulating iron ion oxidation state by high valence manganese ion and stabilizing domain orientation by defect dipole,comprehensive excellent electrical performances(Td=340°C,ρ250°C>10^(7)Ωcm and FOM_(250°C)=4905×10^(–15)m^(2)N^(−1))are realized at the solid solubility limit of manganese ions.The HT-PEHs assembled using the rationally designed piezoceramic can allow for fast charging of commercial electrolytic capacitor at 250°C with high energy conversion efficiency(η=11.43%).These characteristics demonstrate that defect engineering tailored BF-BT can satisfy high-end HT-PEHs requirements,paving a new way in developing selfpowered wireless sensors working in HT environments.展开更多
Rechargeable magnesium batteries(RMBs)have been considered a promising“post lithium-ion battery”system to meet the rapidly increasing demand of the emerging electric vehicle and grid energy storage market.However,th...Rechargeable magnesium batteries(RMBs)have been considered a promising“post lithium-ion battery”system to meet the rapidly increasing demand of the emerging electric vehicle and grid energy storage market.However,the sluggish diffusion kinetics of bivalent Mg^(2+)in the host material,related to the strong Coulomb effect between Mg^(2+)and host anion lattices,hinders their further development toward practical applications.Defect engineering,regarded as an effective strategy to break through the slow migration puzzle,has been validated in various cathode materials for RMBs.In this review,we first thoroughly understand the intrinsic mechanism of Mg^(2+)diffusion in cathode materials,from which the key factors affecting ion diffusion are further presented.Then,the positive effects of purposely introduced defects,including vacancy and doping,and the corresponding strategies for introducing various defects are discussed.The applications of defect engineering in cathode materials for RMBs with advanced electrochemical properties are also summarized.Finally,the existing challenges and future perspectives of defect engineering in cathode materials for the overall high-performance RMBs are described.展开更多
Point defect engineering endows catalysts with novel physical and chemical properties,elevating their electrocatalytic efficiency.The introduction of defects emerges as a promising strategy,effectively modifying the e...Point defect engineering endows catalysts with novel physical and chemical properties,elevating their electrocatalytic efficiency.The introduction of defects emerges as a promising strategy,effectively modifying the electronic structure of active sites.This optimization influences the adsorption energy of intermediates,thereby mitigating reaction energy barriers,altering paths,enhancing selectivity,and ultimately improving the catalytic efficiency of electrocatalysts.To elucidate the impact of defects on the electrocatalytic process,we comprehensively outline the roles of various point defects,their synthetic methodologies,and characterization techniques.Importantly,we consolidate insights into the relationship between point defects and catalytic activity for hydrogen/oxygen evolution and CO_(2)/O_(2)/N_(2) reduction reactions by integrating mechanisms from diverse reactions.This underscores the pivotal role of point defects in enhancing catalytic performance.At last,the principal challenges and prospects associated with point defects in current electrocatalysts are proposed,emphasizing their role in advancing the efficiency of electrochemical energy storage and conversion materials.展开更多
Hydrogen peroxide(H_(2)O_(2))photosynthesis represents an advanced on-site production method with significant potential for on-demand supply.However,various challenges hinder the efficiency of H_(2)O_(2) yield,includi...Hydrogen peroxide(H_(2)O_(2))photosynthesis represents an advanced on-site production method with significant potential for on-demand supply.However,various challenges hinder the efficiency of H_(2)O_(2) yield,including weak oxygen adsorption capacity,reliance on sacrificial agents,low charge separation and transfer efficiency.In this regard,doping design and defect engineering have emerged as robust and effective strategies for catalyst modification,particularly through their synergistic effects.Additionally,advanced in situ characterization techniques for investigating reaction mechanisms are gaining momentum.Herein,this review provides a comprehensive analysis of the fundamentals and challenges associated with photocatalytic H_(2)O_(2) production,and highlights the advantages of doping and defect engineering.Subsequently,it outlines preparation methods and applications of these strategies.More importantly,it emphasizes the advanced characterization techniques utilized to validate doping and defects,as well as to investigate underlying mechanisms.Finally,the potential prospects and challenges of this reaction are anticipated.This review aims to offer valuable insights for researchers from both experimental and theoretical perspectives.展开更多
Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we pro...Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we propose Ag&Se co-selenization strategy to enhance the crystallization and passivate harmful defects of the CIGS films. The formation of Ag-Se phase during the selenization process enables the formation of large grains and suppresses the deep level defects. It is found that Ag doping can enlarge the depletion region width, lower the Urbach energy and prolong the carrier lifetime. As a result, a champion solution-processed CIGS solar cell presents a high efficiency of 16.48% with the highly improved opencircuit voltage(VOC) of 662 m V and fill factor(FF) of 75.8%. This work provides an efficient strategy to prepare high quality solution-processed CIGS films for high-performance CIGS solar cells.展开更多
Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave(EMW)absorption capacity.However,the relationship between them is not clear,especially in soli...Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave(EMW)absorption capacity.However,the relationship between them is not clear,especially in solid solution structures.In this work,a series of(Cr_(1-x)V_(x))_(2)AlC MAX phase solid solutions with layered structure were prepared via tuning the ratio of Cr and V to explore their EMW absorption performance.The experimental results indicated that the doping of V atoms at the M-site could effectively regulate its impedance matching and EMW absorption properties by introducing appropriate numbers of defects in the crystal,such as twin boundaries,dislocations and lattice distortions.Among them,if Cr:V=3:1,Cr_(1.5)V_(0.5)AlC,as radar absorption materials,could reach a strong reflection loss of-51.8 dB at the frequency of 12.8 GHz under an ultra-thin thickness of 1.3 mm.The reflection loss value could attain-10 dB in a wide frequency range of 2.7-18 GHz and thickness range of 1-5 mm.In addition,after high temperature and acid-alkali immersion treatment,this sample still had good EMW absorption capability,and the effective absorption bandwidth was enhanced from 2.3 to 2.6 GHz after concentrated acid immersion or 3.1 GHz after concentrated alkali immersion.This work has great reference significance for the research and development of high-performance MAX-based EMW absorption materials in harsh environments.展开更多
Electrocatalytic carbon dioxide(CO_(2))reduction is an important way to achieve carbon neutrality by converting CO_(2)in-to high-value-added chemicals using electric energy.Carbon-based materials are widely used in va...Electrocatalytic carbon dioxide(CO_(2))reduction is an important way to achieve carbon neutrality by converting CO_(2)in-to high-value-added chemicals using electric energy.Carbon-based materials are widely used in various electrochemical reactions,including electrocatalytic CO_(2)reduction,due to their low cost and high activity.In recent years,defect engineering has attracted wide attention by constructing asymmetric defect centers in the materials,which can optimize the physicochemical properties of the mater-ial and improve its electrocatalytic activity.This review summarizes the types,methods of formation and defect characterization tech-niques of defective carbon-based materials.The advantages of defect engineering and the advantages and disadvantages of various defect formation methods and characterization techniques are also evaluated.Finally,the challenges of using defective carbon-based materials in electrocatalytic CO_(2)reduction are investigated and opportunities for their use are discussed.It is believed that this re-view will provide suggestions and guidance for developing defective carbon-based materials for CO_(2)reduction.展开更多
Owing to the intrinsically sluggish kinetics of urea oxidation reaction(UOR)involving a six-electron transfer process,developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed.Herein,by ...Owing to the intrinsically sluggish kinetics of urea oxidation reaction(UOR)involving a six-electron transfer process,developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed.Herein,by taking advantage of 2-Methylimidazole,of which is a kind of alkali in water and owns strong coordination ability to Co^(2+)in methanol,trace Co(1.0 mol%)addition was found to induce defect engineering onα-Ni(OH)_(2)in a dual-solvent system of water and methanol.Physical characterization results revealed that the synthesized electrocatalyst(WM-Ni_(0.99)Co_(0.01)(OH)_(2))was a kind of defective nanosheet with thickness around 5-6 nm,attributing to the synergistic effect of Co doping and defect engineering,its electron structure was finely altered,and its specific surface a rea was tremendously enlarged from 68 to 172.3 m^(2)g^(-1).With all these merits,its overpotential to drive 10 mA cm^(-2)was reduced by 110 mV.Besides,the interfacial behavior of UOR was also well deciphered by operando electrochemical impedance spectroscopy.展开更多
Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.De...Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.展开更多
Intrinsic topological defect engineering has been proven as a promising strategy to elevate the electrocatalytic activity of carbon materials.However,the controllable construction of high-density and specific topologi...Intrinsic topological defect engineering has been proven as a promising strategy to elevate the electrocatalytic activity of carbon materials.However,the controllable construction of high-density and specific topological defects in carbon frameworks to reveal the relationship between reactivity and defect structure remains a challenging task.Herein,the intrinsic pentagon carbon sites that can favor electron overflow and enhance their binding affinity towards the intermediates of catalytic reaction are firstly presented by the work function and the p-band center calculations.To experimentally verify this,the cage-opening reaction of fullerene is proposed and utilized for synthesizing carbon quantum dots with specific pentagon configuration(CQDs-P),subsequently utilizing CQDs-P to modulate the micro-scale defect density of three-dimensional reduced graphene oxide(rGO)viaπ-πinteractions.The multiple spatial-scale rGO-conjugated CQDs-P structure simultaneously possesses abundant pentagon and edge defects as catalytic active sites and long-range-orderedπelectron delocalization system as conductive network.The defects-rich CQDs-P/rGO-4 all-carbon-based catalyst exhibits superb catalytic activity for triiodide reduction reaction with a high photoelectric conversion efficiency of 8.40%,superior to the Pt reference(7.97%).Theoretical calculations suggest that pentagon defects in the carbon frameworks can promote charge transfer and modulate the adsorption/dissociation behavior of the reaction intermediates,thus enhancing the electrocatalytic activity of the catalyst.This work confirms the role of intrinsic pentagon defects in catalytic reactions and provides a new insight into the synthesis of defects-rich carbon catalysts.展开更多
The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic tw...The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.展开更多
Defect engineering on metal-organic frameworks(MOFs)provides high flexibility to rationally design advanced oxygen evolution reaction(OER)catalysts with low overpotential and high stability.However,fundamental underst...Defect engineering on metal-organic frameworks(MOFs)provides high flexibility to rationally design advanced oxygen evolution reaction(OER)catalysts with low overpotential and high stability.However,fundamental understanding the effect of defect concentration on catalytic OER activity is still quite ambiguous.Herein,the Co-MOF-Dx catalysts with regulated oxygen defects concentration are deliberately constructed via coupling one-pot solvothermal synthesis with NaBH_(4)chemical reduction process.Experimental findings propose that the oxygen defect concentration within Co-MOF-Dx gradually increases with raising the NaBH_(4)content,which could provide a flexible platform to tailor the electronic structure around active Co site and optimize adsorption/desorption capacity of oxygen intermediates.When the introduction content of NaBH_(4)is up to 5 mg,the resulting abundant unsaturated coordination defects could endow the Co-MOF-D5 catalyst with optimized electronic structure and more exposed active sites for improving charge transfer and adsorption/desorption capacity.It is found that the optimized Co-MOF-D5 can drive the current density of 10 mA cm^(-2)only at a low overpotential of 300 mV with the small Tafel slope of 53.1 mV dec^(-1)in alkaline medium.This work sheds light on the way for the development of high-performance MOF catalysts via modulating defect concentration.展开更多
Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivit...Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.展开更多
Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting...Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting the reaction.During the reaction,the presence of oxygen vacancies can extract oxygen from NO,thereby facilitating the cleavage of NO on the catalyst surface.Thus,the formation of oxygen vacancies is key to accelerating the CO-SCR reaction,with different types of oxygen vacancies being more conducive to their generation.In this study,Rh/CeCuO_(x) catalysts were synthesized using the co-crystallization and impregnation methods,and asymmetric oxygen vacancies were induced through hydrogen thermal treatment.This structuralmodification was aimed at regulating the behavior of NO on the catalyst surface.The Rh/Ce0.95Cu0.05O_(x)-H_(2) catalyst exhibited the best performance in CO-SCR,achieving above 90%NO conversion at 162℃.Various characterization techniques showed that the H_(2) treatment effectively reduced some of the CuO and Rh_(2)O_(3),creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface,rather than forming difficult-to-decompose nitrates.This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts.展开更多
The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally...The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.展开更多
Crystal defects and morphological modifications are popular strategies to enhance the catalytic activity of heterogeneous semiconductor photocatalysts.Despite defect engineering and morphology control show their succe...Crystal defects and morphological modifications are popular strategies to enhance the catalytic activity of heterogeneous semiconductor photocatalysts.Despite defect engineering and morphology control show their successful applications in ZnO,the effects of curved surface modifications on the photocatalytic performance of ZnO and their interplay with the defect formation remain unclear.To resolve this puzzle,we systemically investigate the joint effects of curvature and defect formation on the electronic structure,optoelectronic properties,and photocatalytic performance of ZnO slabs using first-principles calculations.We find that curvature deformation effectively narrows the electronic bandgap by up to 1.6 eV and shifts the p-/d-band centers,thereby enhancing light absorption in the visible and near-ultraviolet regions.Besides,curvature deformation stimulates self-polarization,facilitating the separation of photogenerated electrons and holes.Also,curvature deformation promotes the formation of defects by reducing defect formation energy(by up to 1.0 eV),thus creating abundant reaction sites for photocatalysis.Intriguingly,the synergistic interaction between curvature and defect deformation further strengthens the self-polarization,narrows the electronic bandgaps,adjusts the p-/d-band centers to improve the optoelectronic properties,and influences the dissociation and free energy barriers of intermediates.Consequently,our findings reveal that this synergy substantially enhances the photocatalytic performance of ZnO slabs,providing deeper insights into the role of defect engineering and morphology control on photocatalysis.展开更多
Traditionally reduced graphene oxide(RGO)-based electromagnetic wave(EMW)absorbing materials have poor absorption effectiveness due to impedance mismatch caused by skin effect.The introduction of structural defects an...Traditionally reduced graphene oxide(RGO)-based electromagnetic wave(EMW)absorbing materials have poor absorption effectiveness due to impedance mismatch caused by skin effect.The introduction of structural defects and the design of heterogeneous interfaces play a crucial role in enhancing the polarization effect of EMW absorbers.In this study,nitrogen-doped reduced graphene oxide/zinc ferrite@nitrogen-doped carbon(NRGO/ZnFe_(2)O_(4)@NC)ternary composite with rich heterogeneous interfaces is constructed by combining solvothermal reaction,in-situ polymerization,annealing treatment with subsequent hydrothermal reaction.The research results have shown that the obtained NRGO/ZnFe_(2)O_(4)@NC ternary composite exhibits a unique core-shell structure and excellent EMW absorption performance.At a thickness of 2.61 mm,the maximum effective absorption bandwidth can reach 7.2 GHz,spanning the entire Ku-band and a portion of the X-band,and the minimum reflection loss is-61.1 dB,which is superior to most reported RGO-based EMW absorbers.The excellent EMW absorbing ability is mainly ascribed to the optimized impedance matching and the enhanced polarization loss caused by the abundant heterogeneous interfaces and structural defects derived from heteroatomic nitrogen doping.Furthermore,the radar cross section in the far field is simulated by a computer simulation technique.This study provides a novel way to prepare core-shell magnetic carbon composites as highly efficient and broadband EMW absorbers.展开更多
Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin ...Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.展开更多
Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong bin...Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong binding centers(hydroxyl sites and strong acid sites)on the surfaces of nanostructured ceria,which regulate the adsorption process of KA-Oil(the mixture of cyclohexanol and cyclohexanone)and to promote high KA-Oil selectivity in cyclohexane oxidation.The three CeO_(2)(nanocube,nanorod and nanopolyhedron)with different exposed crystal planes were treated by acid etching to change the surface sites and catalytic properties.The transition behavior of surface sites during etching was revealed,abundant strong binding centers were proved to be constructed successfully.And especially for the nanorod treated by acid(Acid@CeO_(2)-NR)with the strongest response for sulfuric acid etching,the strong adsorption of cyclohexanone by strong binding centers was confirmed based on the in-situ DRIFTs.The sulfuric acid etching strategy to enhance the selective oxidation of cyclohexane based on the construction of strong binding centers was proved to be feasible and effective,Acid@CeO_(2)-NR with strongest etching response achieved the dramatic promotion of KA-Oil selectivity from 64.1%to 92.3%.展开更多
基金supported by The National Key R&D Program of China(No.2021YFB3500700)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Researchers have recently developed various surface engineering approaches to modify environmental catalysts and improve their catalytic activity.Defect engineering has proved to be one of the most promising modification methods.Constructing defects on the surface of catalytic materials can effectively modulate the coordination environment of the active sites,affecting and changing the electrons,geometry,and other important properties at the catalytic active sites,thus altering the catalytic activity of the catalysts.However,the conformational relationship between defects and catalytic activity remains to be clarified.This dissertation focuses on an overview of recent advances in defect engineering in environmental catalysis.Based on defining the classification of defects in catalytic materials,defect construction methods,and characterization techniques are summarized and discussed.Focusing on an overview of the characteristics of the role of defects in electrocatalytic,photocatalytic,and thermal catalytic reactions and the mechanism of catalytic reactions.An elaborate link is given between the reaction activity and the structure of catalyst defects.Finally,the existing challenges and possible future directions for the application of defect engineering in environmental catalysis are discussed,which are expected to guide the design and development of efficient environmental catalysts and mechanism studies.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272103 and 52072010)Beijing Natural Science Foundation(Grant Nos.2242029 and JL23004).
文摘High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,including high figure of merit(FOM),insulation resistivity(ρ)and depolarization temperature(Td)are indispensable but hard to achieve in lead-free piezoceramics,especially operating at 250°C has not been reported before.Herein,well-balanced performances are achieved in BiFeO3–BaTiO3 ceramics via innovative defect engineering with respect to delicate manganese doping.Due to the synergistic effect of enhancing electrostrictive coefficient by polarization configuration optimization,regulating iron ion oxidation state by high valence manganese ion and stabilizing domain orientation by defect dipole,comprehensive excellent electrical performances(Td=340°C,ρ250°C>10^(7)Ωcm and FOM_(250°C)=4905×10^(–15)m^(2)N^(−1))are realized at the solid solubility limit of manganese ions.The HT-PEHs assembled using the rationally designed piezoceramic can allow for fast charging of commercial electrolytic capacitor at 250°C with high energy conversion efficiency(η=11.43%).These characteristics demonstrate that defect engineering tailored BF-BT can satisfy high-end HT-PEHs requirements,paving a new way in developing selfpowered wireless sensors working in HT environments.
基金support of the National Natural Science Foundation of China(Grant No.22225801,22178217 and 22308216)supported by the Fundamental Research Funds for the Central Universities,conducted at Tongji University.
文摘Rechargeable magnesium batteries(RMBs)have been considered a promising“post lithium-ion battery”system to meet the rapidly increasing demand of the emerging electric vehicle and grid energy storage market.However,the sluggish diffusion kinetics of bivalent Mg^(2+)in the host material,related to the strong Coulomb effect between Mg^(2+)and host anion lattices,hinders their further development toward practical applications.Defect engineering,regarded as an effective strategy to break through the slow migration puzzle,has been validated in various cathode materials for RMBs.In this review,we first thoroughly understand the intrinsic mechanism of Mg^(2+)diffusion in cathode materials,from which the key factors affecting ion diffusion are further presented.Then,the positive effects of purposely introduced defects,including vacancy and doping,and the corresponding strategies for introducing various defects are discussed.The applications of defect engineering in cathode materials for RMBs with advanced electrochemical properties are also summarized.Finally,the existing challenges and future perspectives of defect engineering in cathode materials for the overall high-performance RMBs are described.
基金supported by the National Natural Science Foundation of China(U21A20281)the Special Fund for Young Teachers from Zhengzhou University(JC23557030,JC23257011)+1 种基金the Key Research Projects of Higher Education Institutions of Henan Province(24A530009)the Project of Zhongyuan Critical Metals Laboratory(GJJSGFYQ202336).
文摘Point defect engineering endows catalysts with novel physical and chemical properties,elevating their electrocatalytic efficiency.The introduction of defects emerges as a promising strategy,effectively modifying the electronic structure of active sites.This optimization influences the adsorption energy of intermediates,thereby mitigating reaction energy barriers,altering paths,enhancing selectivity,and ultimately improving the catalytic efficiency of electrocatalysts.To elucidate the impact of defects on the electrocatalytic process,we comprehensively outline the roles of various point defects,their synthetic methodologies,and characterization techniques.Importantly,we consolidate insights into the relationship between point defects and catalytic activity for hydrogen/oxygen evolution and CO_(2)/O_(2)/N_(2) reduction reactions by integrating mechanisms from diverse reactions.This underscores the pivotal role of point defects in enhancing catalytic performance.At last,the principal challenges and prospects associated with point defects in current electrocatalysts are proposed,emphasizing their role in advancing the efficiency of electrochemical energy storage and conversion materials.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20231342,BK20210867)National Natural Science Foundation of China(22008163)+1 种基金Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(SKLPEE–KF202309)Natural Science Research Project of Higher Education Institutions in Jiangsu Province(21KJB150038).
文摘Hydrogen peroxide(H_(2)O_(2))photosynthesis represents an advanced on-site production method with significant potential for on-demand supply.However,various challenges hinder the efficiency of H_(2)O_(2) yield,including weak oxygen adsorption capacity,reliance on sacrificial agents,low charge separation and transfer efficiency.In this regard,doping design and defect engineering have emerged as robust and effective strategies for catalyst modification,particularly through their synergistic effects.Additionally,advanced in situ characterization techniques for investigating reaction mechanisms are gaining momentum.Herein,this review provides a comprehensive analysis of the fundamentals and challenges associated with photocatalytic H_(2)O_(2) production,and highlights the advantages of doping and defect engineering.Subsequently,it outlines preparation methods and applications of these strategies.More importantly,it emphasizes the advanced characterization techniques utilized to validate doping and defects,as well as to investigate underlying mechanisms.Finally,the potential prospects and challenges of this reaction are anticipated.This review aims to offer valuable insights for researchers from both experimental and theoretical perspectives.
基金National Natural Science Foundation of China (62104061, 62074052, 61974173 and 52072327)。
文摘Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we propose Ag&Se co-selenization strategy to enhance the crystallization and passivate harmful defects of the CIGS films. The formation of Ag-Se phase during the selenization process enables the formation of large grains and suppresses the deep level defects. It is found that Ag doping can enlarge the depletion region width, lower the Urbach energy and prolong the carrier lifetime. As a result, a champion solution-processed CIGS solar cell presents a high efficiency of 16.48% with the highly improved opencircuit voltage(VOC) of 662 m V and fill factor(FF) of 75.8%. This work provides an efficient strategy to prepare high quality solution-processed CIGS films for high-performance CIGS solar cells.
基金financially supported by the National Natural Science Foundation of China(Nos.52275187 and 52202364)Natural Science Foundation of Henan(No.232300421135)+1 种基金Fundamental Research Funds for the Universities of Henan Province(No.NSFRF200101)Henan Postdoctoral Foundation(No.202101035)。
文摘Defects engineering is an effective strategy for manipulating electromagnetic parameters and enhancing electromagnetic wave(EMW)absorption capacity.However,the relationship between them is not clear,especially in solid solution structures.In this work,a series of(Cr_(1-x)V_(x))_(2)AlC MAX phase solid solutions with layered structure were prepared via tuning the ratio of Cr and V to explore their EMW absorption performance.The experimental results indicated that the doping of V atoms at the M-site could effectively regulate its impedance matching and EMW absorption properties by introducing appropriate numbers of defects in the crystal,such as twin boundaries,dislocations and lattice distortions.Among them,if Cr:V=3:1,Cr_(1.5)V_(0.5)AlC,as radar absorption materials,could reach a strong reflection loss of-51.8 dB at the frequency of 12.8 GHz under an ultra-thin thickness of 1.3 mm.The reflection loss value could attain-10 dB in a wide frequency range of 2.7-18 GHz and thickness range of 1-5 mm.In addition,after high temperature and acid-alkali immersion treatment,this sample still had good EMW absorption capability,and the effective absorption bandwidth was enhanced from 2.3 to 2.6 GHz after concentrated acid immersion or 3.1 GHz after concentrated alkali immersion.This work has great reference significance for the research and development of high-performance MAX-based EMW absorption materials in harsh environments.
文摘Electrocatalytic carbon dioxide(CO_(2))reduction is an important way to achieve carbon neutrality by converting CO_(2)in-to high-value-added chemicals using electric energy.Carbon-based materials are widely used in various electrochemical reactions,including electrocatalytic CO_(2)reduction,due to their low cost and high activity.In recent years,defect engineering has attracted wide attention by constructing asymmetric defect centers in the materials,which can optimize the physicochemical properties of the mater-ial and improve its electrocatalytic activity.This review summarizes the types,methods of formation and defect characterization tech-niques of defective carbon-based materials.The advantages of defect engineering and the advantages and disadvantages of various defect formation methods and characterization techniques are also evaluated.Finally,the challenges of using defective carbon-based materials in electrocatalytic CO_(2)reduction are investigated and opportunities for their use are discussed.It is believed that this re-view will provide suggestions and guidance for developing defective carbon-based materials for CO_(2)reduction.
基金supported by the Central South University Scientific Research Foundation for Post-doctor(Grant No.:140050052)the National Natural Science Foundation of China(Grant No.:52204325)
文摘Owing to the intrinsically sluggish kinetics of urea oxidation reaction(UOR)involving a six-electron transfer process,developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed.Herein,by taking advantage of 2-Methylimidazole,of which is a kind of alkali in water and owns strong coordination ability to Co^(2+)in methanol,trace Co(1.0 mol%)addition was found to induce defect engineering onα-Ni(OH)_(2)in a dual-solvent system of water and methanol.Physical characterization results revealed that the synthesized electrocatalyst(WM-Ni_(0.99)Co_(0.01)(OH)_(2))was a kind of defective nanosheet with thickness around 5-6 nm,attributing to the synergistic effect of Co doping and defect engineering,its electron structure was finely altered,and its specific surface a rea was tremendously enlarged from 68 to 172.3 m^(2)g^(-1).With all these merits,its overpotential to drive 10 mA cm^(-2)was reduced by 110 mV.Besides,the interfacial behavior of UOR was also well deciphered by operando electrochemical impedance spectroscopy.
基金National Natural Science Foundation of China,Grant/Award Number:52271200Scientific and Technological Innovation Foundation of Foshan,Grant/Award Number:BK20BE009+1 种基金the Fundamental Research Funds for the Central Universities,Grant/Award Number:FRF-TP-18-079A1Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2020A1515110460,ORCID:http://orcid.org/0000-0002-0870-2248。
文摘Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.
基金partly supported by the National Natural Science Foundation of China(22078052)the National Key R&D Program of China(2022YFB4101602)the Fundamental Research Funds for the Central Universities(DUT22LAB612)。
文摘Intrinsic topological defect engineering has been proven as a promising strategy to elevate the electrocatalytic activity of carbon materials.However,the controllable construction of high-density and specific topological defects in carbon frameworks to reveal the relationship between reactivity and defect structure remains a challenging task.Herein,the intrinsic pentagon carbon sites that can favor electron overflow and enhance their binding affinity towards the intermediates of catalytic reaction are firstly presented by the work function and the p-band center calculations.To experimentally verify this,the cage-opening reaction of fullerene is proposed and utilized for synthesizing carbon quantum dots with specific pentagon configuration(CQDs-P),subsequently utilizing CQDs-P to modulate the micro-scale defect density of three-dimensional reduced graphene oxide(rGO)viaπ-πinteractions.The multiple spatial-scale rGO-conjugated CQDs-P structure simultaneously possesses abundant pentagon and edge defects as catalytic active sites and long-range-orderedπelectron delocalization system as conductive network.The defects-rich CQDs-P/rGO-4 all-carbon-based catalyst exhibits superb catalytic activity for triiodide reduction reaction with a high photoelectric conversion efficiency of 8.40%,superior to the Pt reference(7.97%).Theoretical calculations suggest that pentagon defects in the carbon frameworks can promote charge transfer and modulate the adsorption/dissociation behavior of the reaction intermediates,thus enhancing the electrocatalytic activity of the catalyst.This work confirms the role of intrinsic pentagon defects in catalytic reactions and provides a new insight into the synthesis of defects-rich carbon catalysts.
文摘The development of low-cost,abundant,and efficient non-metal catalysts has always been a research focus on photocatalytic hydrogen evolution reactions.Boron nitride nanosheet(BNNS),which is a promising non-metallic two-dimensional material,possesses remarkable properties.However,its inherently wide bandgap significantly limits their potential for visible-light-responsive catalysis,and conventional chemical methods struggle to overcome this limitation.In this study,we employed high-energy ionizing radiation to precisely regulate defect formation in BNNS at ambient temperature and pressure.The results showed that gamma-ray radiation markedly enhanced the efficiency of photocatalytic hydrogen production of the irradiated BNNS with increasing absorbed dose.The maximum hydrogen production rate of the samples reached 1033.7μmol/(g·h),which represents an increase of almost two orders of magnitude compared to commercial BNNS.The structural characterization also confirmed that the introduction of three-boron-center defects results in forming intermediate energy levels and improving the charge carrier separation efficiency of BNNS.This transformation converts BNNS from a wide bandgap semiconductor to a visible-light-responsive catalyst.This work not only provides a novel approach for the application of BNNS in visible-light photocatalysis,but also demonstrates the unique role of radiation technology in quantitatively regulating defects and improving catalytic activity.
基金supported by the National Natural Science Foundation of China(52261145700,22279124)the Natural Science Foundation of Shandong Province(ZR202ZD30)Qingdao New Energy Shandong Laboratory Open Project(QNESL OP202307)
文摘Defect engineering on metal-organic frameworks(MOFs)provides high flexibility to rationally design advanced oxygen evolution reaction(OER)catalysts with low overpotential and high stability.However,fundamental understanding the effect of defect concentration on catalytic OER activity is still quite ambiguous.Herein,the Co-MOF-Dx catalysts with regulated oxygen defects concentration are deliberately constructed via coupling one-pot solvothermal synthesis with NaBH_(4)chemical reduction process.Experimental findings propose that the oxygen defect concentration within Co-MOF-Dx gradually increases with raising the NaBH_(4)content,which could provide a flexible platform to tailor the electronic structure around active Co site and optimize adsorption/desorption capacity of oxygen intermediates.When the introduction content of NaBH_(4)is up to 5 mg,the resulting abundant unsaturated coordination defects could endow the Co-MOF-D5 catalyst with optimized electronic structure and more exposed active sites for improving charge transfer and adsorption/desorption capacity.It is found that the optimized Co-MOF-D5 can drive the current density of 10 mA cm^(-2)only at a low overpotential of 300 mV with the small Tafel slope of 53.1 mV dec^(-1)in alkaline medium.This work sheds light on the way for the development of high-performance MOF catalysts via modulating defect concentration.
基金financially supported by the National Natural Science Foundation of China (Grant No.52171221)the National Key Research and Development Program of China (Grant No.2019YFA0704900)。
文摘Ga-doped Li_(7)La_(3)Zr_(2)O_(12)(Ga-LLZO)has long been considered as a promising garnet-type electrolyte candidate for all-solid-state lithium metal batteries(ASSLBs)due to its high room temperature ionic conductivity.However,the typical synthesis of Ga-LLZO is usually accompanied by the formation of undesired LiGaO_(2) impurity phase that causes severe instability of the electrolyte in contact with molten Li metal during half/full cell assembly.In this study,we show that by simply engineering the defect chemistry of Ga-LLZO,namely,the lithium deficiency level,LiGaO_(2) impurity phase is effectively inhibited in the final synthetic product.Consequently,defect chemistry engineered Ga-LLZO exhibits excellent electrochemical stability against lithium metal,while its high room temperature ionic conductivity(~1.9×10^(-3)S·cm^(-1))is well reserved.The assembled Li/Ga-LLZO/Li symmetric cell has a superior critical current density of 0.9 mA·cm^(-2),and cycles stably for 500 hours at a current density of 0.3 mA·cm^(-2).This research facilitates the potential commercial applications of high performance Ga-LLZO solid electrolytes in ASSLBs.
基金supported by the support of the National Natural Science Foundation of China(Nos.22072141,22176185 and 52304429)the National Key Research and Development Program of China(Nos.2022YFB3504200,2021YFB3501900)+4 种基金the Natural Science Foundation of Jiangxi Province for Distinguished Young Scholars(No.20232ACB213004)Jiangxi Provincial Key Research and Development Program(No.20232BBG70012)Jiangxi Provincial Natural Science Foundation(No.20212BAB213032)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2018263)the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(No.E355C001).
文摘Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting the reaction.During the reaction,the presence of oxygen vacancies can extract oxygen from NO,thereby facilitating the cleavage of NO on the catalyst surface.Thus,the formation of oxygen vacancies is key to accelerating the CO-SCR reaction,with different types of oxygen vacancies being more conducive to their generation.In this study,Rh/CeCuO_(x) catalysts were synthesized using the co-crystallization and impregnation methods,and asymmetric oxygen vacancies were induced through hydrogen thermal treatment.This structuralmodification was aimed at regulating the behavior of NO on the catalyst surface.The Rh/Ce0.95Cu0.05O_(x)-H_(2) catalyst exhibited the best performance in CO-SCR,achieving above 90%NO conversion at 162℃.Various characterization techniques showed that the H_(2) treatment effectively reduced some of the CuO and Rh_(2)O_(3),creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface,rather than forming difficult-to-decompose nitrates.This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts.
文摘The development of metal-free carbon catalysts has garnered significant attention as a promising approach to address the challenges of sustainable catalysis,particularly in the replacement of toxic and environmentally hazardous mercury-based systems for the coal-based PVC industry.Within a decade of development,the catalytic performance of carbon catalysts has been improved greatly and even shows superiorities over metal catalysts in some cases,which have demonstrated great potential as sustainable alternatives to mercury catalysts.This review provides a comprehensive summary of the recent advancements in carbon catalysts for acetylene hydrochlorination.It encompasses a wide range of aspects,including the identification of active sites from heteroatom doping to intrinsic carbon defects,the various synthetic strategies employed,the reaction and deactivation mechanisms of carbon catalysts,and the current insights into the key challenges that are encountered on the journey from laboratory research to scalable commercialization within the field of carbon catalysts.The review offers foundational insights and practical guidelines for designing green carbon catalysts systems,not only for acetylene hydrochlorination but also for other heterogeneous catalytic reactions.
基金supported by the National Key R&D Program of China(No.2021YFA1502300)the National Natural Science Foundation of China(Nos.22103012,22173105)+2 种基金the Natural Science Foundation of Fujian Province(Nos.2024J01456,2024J01191)the Selfdeployment Project Research Program of Haixi Institutes,Chinese Academy of Sciences(No.CXZX-2022-GH10)the CAS Youth Interdisciplinary Team.
文摘Crystal defects and morphological modifications are popular strategies to enhance the catalytic activity of heterogeneous semiconductor photocatalysts.Despite defect engineering and morphology control show their successful applications in ZnO,the effects of curved surface modifications on the photocatalytic performance of ZnO and their interplay with the defect formation remain unclear.To resolve this puzzle,we systemically investigate the joint effects of curvature and defect formation on the electronic structure,optoelectronic properties,and photocatalytic performance of ZnO slabs using first-principles calculations.We find that curvature deformation effectively narrows the electronic bandgap by up to 1.6 eV and shifts the p-/d-band centers,thereby enhancing light absorption in the visible and near-ultraviolet regions.Besides,curvature deformation stimulates self-polarization,facilitating the separation of photogenerated electrons and holes.Also,curvature deformation promotes the formation of defects by reducing defect formation energy(by up to 1.0 eV),thus creating abundant reaction sites for photocatalysis.Intriguingly,the synergistic interaction between curvature and defect deformation further strengthens the self-polarization,narrows the electronic bandgaps,adjusts the p-/d-band centers to improve the optoelectronic properties,and influences the dissociation and free energy barriers of intermediates.Consequently,our findings reveal that this synergy substantially enhances the photocatalytic performance of ZnO slabs,providing deeper insights into the role of defect engineering and morphology control on photocatalysis.
基金supported by the Open Research Fund Program of Engineering Technology Research Center of Coal Resources Comprehensive Utilization,Anhui Province,Anhui University of Science and Technology(Grant No.MTYJZX202301)the Anhui Provincial Natural Science Foundation(Grant No.2008085J27).
文摘Traditionally reduced graphene oxide(RGO)-based electromagnetic wave(EMW)absorbing materials have poor absorption effectiveness due to impedance mismatch caused by skin effect.The introduction of structural defects and the design of heterogeneous interfaces play a crucial role in enhancing the polarization effect of EMW absorbers.In this study,nitrogen-doped reduced graphene oxide/zinc ferrite@nitrogen-doped carbon(NRGO/ZnFe_(2)O_(4)@NC)ternary composite with rich heterogeneous interfaces is constructed by combining solvothermal reaction,in-situ polymerization,annealing treatment with subsequent hydrothermal reaction.The research results have shown that the obtained NRGO/ZnFe_(2)O_(4)@NC ternary composite exhibits a unique core-shell structure and excellent EMW absorption performance.At a thickness of 2.61 mm,the maximum effective absorption bandwidth can reach 7.2 GHz,spanning the entire Ku-band and a portion of the X-band,and the minimum reflection loss is-61.1 dB,which is superior to most reported RGO-based EMW absorbers.The excellent EMW absorbing ability is mainly ascribed to the optimized impedance matching and the enhanced polarization loss caused by the abundant heterogeneous interfaces and structural defects derived from heteroatomic nitrogen doping.Furthermore,the radar cross section in the far field is simulated by a computer simulation technique.This study provides a novel way to prepare core-shell magnetic carbon composites as highly efficient and broadband EMW absorbers.
基金supported by the National Natural Science Foundation of China(Grant Nos.11727902,12074372,12174385,12334014,and 12304112).
文摘Hexagonal boron nitride(h-BN)has emerged as a promising two-dimensional material for quantum and optoelectronic applications,with its unique ability to host engineered defects enabling single-photon emission and spin manipulation.This study investigates defect formation in h-BN using focused helium ion beam(He^(+)FIB)irradiation and post-annealing treatments.We demonstrate that helium ion irradiation at doses up to 2×10^(9) ions/μm^(2) does not induce phase transitions or amorphization.Spectroscopic analyses,including differential reflectance spectroscopy(DRS),photoluminescence(PL),and Raman spectroscopy,reveal substantial defect formation and structural modifications.Notably,the irradiation induces a softening of in-plane and interlayer phonon modes,characterized by frequency redshifts of 10.5 cm^(-1) and 3.2 cm^(-1),respectively.While high-temperature thermal annealing mitigates lattice defects and facilitates single-photon emission,the E_(2g) peak width remains 38%broader and the shear mode peak width is 60%broader compared to pre-annealing conditions in the Raman spectra,indicating residual structural degradation.These findings provide insights into defect engineering mechanisms in h-BN,offering guidance for optimizing processing conditions and advancing quantum and optoelectronic device technologies.
基金supported by National Natural Science Fund for Excellent Young Scholars(22222813)the National Natural Science Foundation of China(22078338)+2 种基金the National Key Research and Development Program of China(2023YFA1506803)the Postdoctoral Fellowship Program of CPSF(GZC20232700)the“Special Research Assistant Project”of the Chinese Academy of Sciences.
文摘Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong binding centers(hydroxyl sites and strong acid sites)on the surfaces of nanostructured ceria,which regulate the adsorption process of KA-Oil(the mixture of cyclohexanol and cyclohexanone)and to promote high KA-Oil selectivity in cyclohexane oxidation.The three CeO_(2)(nanocube,nanorod and nanopolyhedron)with different exposed crystal planes were treated by acid etching to change the surface sites and catalytic properties.The transition behavior of surface sites during etching was revealed,abundant strong binding centers were proved to be constructed successfully.And especially for the nanorod treated by acid(Acid@CeO_(2)-NR)with the strongest response for sulfuric acid etching,the strong adsorption of cyclohexanone by strong binding centers was confirmed based on the in-situ DRIFTs.The sulfuric acid etching strategy to enhance the selective oxidation of cyclohexane based on the construction of strong binding centers was proved to be feasible and effective,Acid@CeO_(2)-NR with strongest etching response achieved the dramatic promotion of KA-Oil selectivity from 64.1%to 92.3%.
