Na_(3)V_(2)(PO_(4))_(3)(NVP),as a great potential cathode candidate for Na-ion batteries(NIBs),has attracted enormous interest due to its three-dimensional(3D)large open framework for convenient Na+transport,yet its p...Na_(3)V_(2)(PO_(4))_(3)(NVP),as a great potential cathode candidate for Na-ion batteries(NIBs),has attracted enormous interest due to its three-dimensional(3D)large open framework for convenient Na+transport,yet its practical application is still limited by its inferior electron conductivity and sluggish Na+diffusion kinetics.Herein,the tiny Cr doped hierarchical NVP micro-flower cathodes(i.e.,Na_(3)V_(2-x)Crx(PO_(4))_(3)@C,x≤0.1),which are self-assembled with single-crystal nanoflake subunits in-situ coated with carbon nano-shell,are designed and fabricated via a scalable avenue.The optimized cathode,i.e.,Na_(3)V_(1.94)Cr_(0.06)(PO_(4))_(3)@C(NVCP-6),was endowed with more electro-active Na(2)sites and higher electronic/ionic conductivity for efficient sodium storage.Benefiting from these competitive merits,the NVCP-6,when evaluated as a cathode towards NIBs,exhibits an ultrahigh-rate capability of 99.8 mAh·g^(-1)at 200 C and superior stability of 82.2%over 7300 cycles at 50 C.Furthermore,the NVCP-6 based full NIBs display remarkable electrochemical properties in terms of both high-rate capacities and long-duration cycling properties at different temperatures(-20–50°C).The contribution,i.e.,the design of“four ounces can move a thousand pounds”,here will promote the practical industrial application of NVP towards advanced NIBs.展开更多
In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5...In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5Mn1.5O4 on the structures and electrochemical properties were investigated. The samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, galvanostatic charge-discharge test and electrochemical impedance spectrum （EIS）. The results indicate that the LiCr2 Ni0.5 Mn1.5 O possess a spinel structure and small particle size, and LiCr0.2Ni0.4Mn1.4O4exhibits Y -Y -Y 4 the best cyclic and rate performance. It can deliver discharge capacities of 143 and 104 mA·h/g at 1C and 10C, respectively, with good capacity retention of 96.5% at 1C after 50 cycles.展开更多
A series of Cr doped TiO2 films were prepared by micro arc oxidation （MAO） using an electrolyte of Na3PO4＋K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anat...A series of Cr doped TiO2 films were prepared by micro arc oxidation （MAO） using an electrolyte of Na3PO4＋K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3＋/Cr4＋ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band （CB） and valence band （VB） of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.展开更多
Driven by endless solar energy,photocatalytic H2 evolution from water splitting and CO_(2) conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhou...Driven by endless solar energy,photocatalytic H2 evolution from water splitting and CO_(2) conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhouse effect and energy shortage.Herein,Cr-doped zinc sulfide(ZnS)with accompanying sulphur vacancies(Vs)photocatalytic materials is developed by a facile hydrothermal method.The Cr dopants centralize photoinduced holes and Vs trap electrons,forming a synergistic effect for accelerating charge separation and transfer.The reaction energy barrier for both H2 evolution and CO_(2) reduction has been optimized.Therefore,in the absence of a cocatalyst,the optimal catalyst(Zn_(0.94) Cr_(0.06) S)achieves an out-standing H_(2) evolution activity of 20.3 mmol g^(-1) h^(-1),which is approximately 2.9 times higher than 6.9 mmol g^(-1) h^(-1) for pristine ZnS.In addition,in the gas-solid reaction system without co-catalysts or sacrificial agents,the Zn_(0.94) Cr_(0.06) S exhibits a considerable CO evolution rate of 19.56μmol g^(-1) h^(-1),about 10.1 times higher than ZnS(1.94μmol g^(-1) h^(-1)).Both the performances for H_(2) evolution and CO_(2) reduction of Zn_(0.94) Cr_(0.06) S outperform most of the previously reported photocatalysts.Particularly,the Zn_(0.94) Cr_(0.06) S possesses superior stability,the photoactivity of which exhibits no noticeable deactiva-tion after six cycles’reactions.This work may shed light on the rational design and fabrication of highly efficient materials via combining individual element doping and defect engineering.展开更多
The Cr doped into TiO2(110) surface has been studied systematically by using periodic DFT/B3LYP method with slab model. It is found that doping Cr into perfect TiO2 (110) surface can reduce the value of band-gap from ...The Cr doped into TiO2(110) surface has been studied systematically by using periodic DFT/B3LYP method with slab model. It is found that doping Cr into perfect TiO2 (110) surface can reduce the value of band-gap from 3.13 to 1.16 eV, and then photocatalysis reaction may be achieved in visual light area. The results are in good agreement with the experiments.展开更多
α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoele...α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoelectron spectroscopy（XPS） and inductive coupled plasma（ICP） techniques.The particles reserve shuttle-like shape in the presence of Cr^3＋.The crystallite sizes of Fe2O3 become smaller with the increased Cr^3＋ concentration in solution.The responses of Cr doped α-Fe2O3 sensors were studied towards reducing gases such as ethanol,methanol,acetone,gasoline and n-hexane.Gas sensors based on these materials have higher sensitivities and rapid response/recovery time to alcohol than to hydrocarbon.展开更多
Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxid...Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxide fuel cells(SOFCs)research.Herein,a new hexagonal structure-based cathode material was developed with the co-doping of Gd_(2)O_(3)and Cr_(2)O_(3)of parent SrFe_(12)O_(19)oxide,respectively.At 550-475℃,Sr_(0.90)Gd_(0.10)Fe_(11.90)Cr_(0.10)O_(19)(SFO-10)cathode sample leading to the large peak power density(PPD)of 395 mW/cm^(2),has appropriate surface oxygen defects(O_(β))up to 17%,as verified by X-ray photoelectron microscopy(XPS).Theoretical calculations reveal that the co-doping of Gd and Cr oxides creates lattice disorder at the hexagonal lattice,which decreases the energy barrier for ion transport and enhances the electrocatalytic characteristics of ORR.Consequently,the SFO-10 cathode shows a favorable ORR activity with the least lower polarization resistance(ASR)at 550℃with gadolinium-doped ceria(GDC)electrolyte.This work provides a self-assembled single-phase hexagonal cathode to accelerate the lowtemperature hindrance of SOFC technology.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
The properties of undoped, Cr-doped, and In-doped bulk ZnTe crystals grown by the TGSG method were compared. Cr/In-doping leads to a slight red-shift of the absorption edge. Cr-doping also creates two characteristic a...The properties of undoped, Cr-doped, and In-doped bulk ZnTe crystals grown by the TGSG method were compared. Cr/In-doping leads to a slight red-shift of the absorption edge. Cr-doping also creates two characteristic absorption bands, centered at about 1750 nm and beneath the fundamental absorption edge. However, the fundamental reflectance spectra are not sensitive to the dopants. The resistivity of undoped, Cr-doped, and In-doped ZnTe is about 102 Ω.cm, 10^3 Ω.cm, and 10^8 Ω-cm, respectively. Only In-doped ZnTe has an IR transmittance higher than 60% in the range of 500 to 4000 cm-1. However, the IR transmittance of Cr-doped ZnTe is very low and decreases greatly as the wavenumber increases, which is mainly attributed to the scattering effects caused by some defects generated by Cr-doping.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51904115,52072151,52171211,52271218,and U22A20145)Taishan Scholars(No.ts201712050)+1 种基金Jinan Independent Innovative Team(No.2020GXRC015)Major Program of Shandong Province Natural Science Foundation(No.ZR2021ZD05).
文摘Na_(3)V_(2)(PO_(4))_(3)(NVP),as a great potential cathode candidate for Na-ion batteries(NIBs),has attracted enormous interest due to its three-dimensional(3D)large open framework for convenient Na+transport,yet its practical application is still limited by its inferior electron conductivity and sluggish Na+diffusion kinetics.Herein,the tiny Cr doped hierarchical NVP micro-flower cathodes(i.e.,Na_(3)V_(2-x)Crx(PO_(4))_(3)@C,x≤0.1),which are self-assembled with single-crystal nanoflake subunits in-situ coated with carbon nano-shell,are designed and fabricated via a scalable avenue.The optimized cathode,i.e.,Na_(3)V_(1.94)Cr_(0.06)(PO_(4))_(3)@C(NVCP-6),was endowed with more electro-active Na(2)sites and higher electronic/ionic conductivity for efficient sodium storage.Benefiting from these competitive merits,the NVCP-6,when evaluated as a cathode towards NIBs,exhibits an ultrahigh-rate capability of 99.8 mAh·g^(-1)at 200 C and superior stability of 82.2%over 7300 cycles at 50 C.Furthermore,the NVCP-6 based full NIBs display remarkable electrochemical properties in terms of both high-rate capacities and long-duration cycling properties at different temperatures(-20–50°C).The contribution,i.e.,the design of“four ounces can move a thousand pounds”,here will promote the practical industrial application of NVP towards advanced NIBs.
基金Project(2007BA201055)supported by the National Science and Technology Support Program,China
文摘In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5Mn1.5O4 on the structures and electrochemical properties were investigated. The samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, galvanostatic charge-discharge test and electrochemical impedance spectrum （EIS）. The results indicate that the LiCr2 Ni0.5 Mn1.5 O possess a spinel structure and small particle size, and LiCr0.2Ni0.4Mn1.4O4exhibits Y -Y -Y 4 the best cyclic and rate performance. It can deliver discharge capacities of 143 and 104 mA·h/g at 1C and 10C, respectively, with good capacity retention of 96.5% at 1C after 50 cycles.
文摘A series of Cr doped TiO2 films were prepared by micro arc oxidation （MAO） using an electrolyte of Na3PO4＋K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3＋/Cr4＋ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band （CB） and valence band （VB） of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.
基金supported by the National Natural Sci-ence Foundation of China(No.52002158)the Natural Science Foundation of Jiangxi Province(Nos.20204BCJL23039,20192ACBL21027)The authors would like to thank Prince Sultan University for computational support and Wenjuan Li from Shiyan-jia Lab(www.shiyanjia.com)for the XPS analysis.
文摘Driven by endless solar energy,photocatalytic H2 evolution from water splitting and CO_(2) conversion to hydrocarbon fuels over semiconductor photocatalysts are of great potential to simultaneously settle the greenhouse effect and energy shortage.Herein,Cr-doped zinc sulfide(ZnS)with accompanying sulphur vacancies(Vs)photocatalytic materials is developed by a facile hydrothermal method.The Cr dopants centralize photoinduced holes and Vs trap electrons,forming a synergistic effect for accelerating charge separation and transfer.The reaction energy barrier for both H2 evolution and CO_(2) reduction has been optimized.Therefore,in the absence of a cocatalyst,the optimal catalyst(Zn_(0.94) Cr_(0.06) S)achieves an out-standing H_(2) evolution activity of 20.3 mmol g^(-1) h^(-1),which is approximately 2.9 times higher than 6.9 mmol g^(-1) h^(-1) for pristine ZnS.In addition,in the gas-solid reaction system without co-catalysts or sacrificial agents,the Zn_(0.94) Cr_(0.06) S exhibits a considerable CO evolution rate of 19.56μmol g^(-1) h^(-1),about 10.1 times higher than ZnS(1.94μmol g^(-1) h^(-1)).Both the performances for H_(2) evolution and CO_(2) reduction of Zn_(0.94) Cr_(0.06) S outperform most of the previously reported photocatalysts.Particularly,the Zn_(0.94) Cr_(0.06) S possesses superior stability,the photoactivity of which exhibits no noticeable deactiva-tion after six cycles’reactions.This work may shed light on the rational design and fabrication of highly efficient materials via combining individual element doping and defect engineering.
基金This work was supported by the State Key Laboratory of Structural Chemistry, the National Natural Science Foundation of China (20273013), and the Education Foundation of Fujian Province (JA03007)
文摘The Cr doped into TiO2(110) surface has been studied systematically by using periodic DFT/B3LYP method with slab model. It is found that doping Cr into perfect TiO2 (110) surface can reduce the value of band-gap from 3.13 to 1.16 eV, and then photocatalysis reaction may be achieved in visual light area. The results are in good agreement with the experiments.
基金Supported by the National Natural Science Foundation of China(No.40772026)
文摘α-Fe2O3 nanoparticles doped with various molar fractions of Cr^3＋ were synthesized by a forced hydrolysis route and were characterized by X-ray diffraction（XRD）,scanning electronic microscopy（SEM）,X-ray photoelectron spectroscopy（XPS） and inductive coupled plasma（ICP） techniques.The particles reserve shuttle-like shape in the presence of Cr^3＋.The crystallite sizes of Fe2O3 become smaller with the increased Cr^3＋ concentration in solution.The responses of Cr doped α-Fe2O3 sensors were studied towards reducing gases such as ethanol,methanol,acetone,gasoline and n-hexane.Gas sensors based on these materials have higher sensitivities and rapid response/recovery time to alcohol than to hydrocarbon.
基金Project supported by the Scientific and Technological Innovation Team of Nanjing(NINGJIAOGAOSHI 2021 No.16)。
文摘Enhancing the electrocatalytic activity of the electrode materials,specifically oxygen reduction reaction(ORR),at lower operating temperatures(<600℃)is the prime rank to realize the commercialization of solid oxide fuel cells(SOFCs)research.Herein,a new hexagonal structure-based cathode material was developed with the co-doping of Gd_(2)O_(3)and Cr_(2)O_(3)of parent SrFe_(12)O_(19)oxide,respectively.At 550-475℃,Sr_(0.90)Gd_(0.10)Fe_(11.90)Cr_(0.10)O_(19)(SFO-10)cathode sample leading to the large peak power density(PPD)of 395 mW/cm^(2),has appropriate surface oxygen defects(O_(β))up to 17%,as verified by X-ray photoelectron microscopy(XPS).Theoretical calculations reveal that the co-doping of Gd and Cr oxides creates lattice disorder at the hexagonal lattice,which decreases the energy barrier for ion transport and enhances the electrocatalytic characteristics of ORR.Consequently,the SFO-10 cathode shows a favorable ORR activity with the least lower polarization resistance(ASR)at 550℃with gadolinium-doped ceria(GDC)electrolyte.This work provides a self-assembled single-phase hexagonal cathode to accelerate the lowtemperature hindrance of SOFC technology.
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.
基金Project supported by the National Basic Research Program of China(No.2011CB610406)the National Natural Science Foundation of China(No.51372205)+3 种基金the 111 Project of China(No.B08040)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20116102120014)the NWPU Foundation for Fundamental Researchthe Research Fund of the State Key Laboratory of Solidification Processing(NWPU)
文摘The properties of undoped, Cr-doped, and In-doped bulk ZnTe crystals grown by the TGSG method were compared. Cr/In-doping leads to a slight red-shift of the absorption edge. Cr-doping also creates two characteristic absorption bands, centered at about 1750 nm and beneath the fundamental absorption edge. However, the fundamental reflectance spectra are not sensitive to the dopants. The resistivity of undoped, Cr-doped, and In-doped ZnTe is about 102 Ω.cm, 10^3 Ω.cm, and 10^8 Ω-cm, respectively. Only In-doped ZnTe has an IR transmittance higher than 60% in the range of 500 to 4000 cm-1. However, the IR transmittance of Cr-doped ZnTe is very low and decreases greatly as the wavenumber increases, which is mainly attributed to the scattering effects caused by some defects generated by Cr-doping.
