In this paper, we report a new kind of moist chemical method for preparing LiNiVO 4 which can be used to prepare lithium ion battery for the cathode active materials with a very high battery voltage(48 V vs. Li). Li 2...In this paper, we report a new kind of moist chemical method for preparing LiNiVO 4 which can be used to prepare lithium ion battery for the cathode active materials with a very high battery voltage(48 V vs. Li). Li 2CO 3, NiCO 3 and NH 4VO 3 were used as row materials, and H 2C 2O 4 saturated solution was used both as a precipitate agent and as a complex agent. The precursor gel composed of (NH 4) 2(VO) 2(C 2O 4) 4·6H 2O, NiC 2O 4·2H 2O and Li 2C 2O 4 can be obtained, and after sintering the dry gel we got the products. The results of XRD show that the product sintered at 400 ℃ for 2 h exists in a cubic crystal, single phase, inverse LiNiVO 4 and the average sizes (by Scherrer formula ) were 40—50 nm(400 ℃, 2 h ) and 65—70 nm(700 ℃, 2 h) , respectively, a=0.822 3(1) nm. The TG and DTA curves implied that the dry gel underwent water loss, decompositions of oxalates and complex oxalate, the solid state reactions finished at 377 ℃. The results of XPS proved that the valence in LiNiVO 4 would be Li+,V 5+ , Ni 2+ (in the main), respectively. From ICP analysis we also knew that the sample corresponded basically to stoichiometry LiNiVO 4 .展开更多
A robust oxygen‐related electrocatalyst,composed of spinel iron‐cobalt oxide and nitrogen‐dopedordered mesoporous carbon(NOMC),was developed for rechargeable metal‐air batteries.Electrochemicaltests revealed that ...A robust oxygen‐related electrocatalyst,composed of spinel iron‐cobalt oxide and nitrogen‐dopedordered mesoporous carbon(NOMC),was developed for rechargeable metal‐air batteries.Electrochemicaltests revealed that the optimal catalyst Fe_(0.5)Co/NOMC exhibits superior activity with ahalf‐wave potential of 0.89 V(vs.reversible hydrogen electrode)for the oxygen reduction reactionand an overpotential of 0.31 V at 10 mA cm^(−2)for the oxygen evolution reaction.For demonstration,the catalyst was used in the assembly of a rechargeable zinc‐air battery,which exhibited an exceptionallyhigh energy density of 820 Wh kg−1 at 100 mA cm^(−2),a high power density of 153 mW cm^(−2)at1.0 V,and superior cycling stability up to 432 cycles(144 h)under ambient air.展开更多
Oxygen evolution reaction is one of the key processes in the promising renewable energy technique of electrocatalytic water splitting.Developing high ecient oxygen evolution reaction(OER)catalysts requires determinati...Oxygen evolution reaction is one of the key processes in the promising renewable energy technique of electrocatalytic water splitting.Developing high ecient oxygen evolution reaction(OER)catalysts requires determination of the optimal values of the descriptor parameters.Using spinel CoFe2O4 as the model catalyst,this work demonstrates that irradiation with pulsed UV laser can control the quantity of surface oxygen vacancy and thus modify the OER activity,in a volcano-shape evolution trend.This strategy sheds light on quantita-tively investigation of the relationship between surface cation valence,anion vacancy,and physicochemical properties of transition-metal-based compounds.展开更多
From the UV?Vis absorption spectra,the FT-IR absorption spectra and the Raman spectra,it is deduced that Co ionsprimarily occupy the tetrahedral(A)site,with a minor number of them entering into the octahedral(B)site i...From the UV?Vis absorption spectra,the FT-IR absorption spectra and the Raman spectra,it is deduced that Co ionsprimarily occupy the tetrahedral(A)site,with a minor number of them entering into the octahedral(B)site in the Ni1?xCoxCr2O4compounds.The origin of the position disorder of the Co ions is consistent with the similar ionic radii of the Co ion(0.65?)and theCr ion(0.62?)at B site.The FT-IR peak at about510cm?1shifts towards high frequency side with the increasing cobalt content.Itis resulted from the reduction of the cation?oxygen distance in the octahedron by the replacement of the Ni2+with the Co2+ions.Themagnetic measurement shows that Curie temperatures(TC)are75and90K for the compounds with x=0.2and0.8,respectively.展开更多
Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction(ORR).However,they are usually synthesized through oxidation-precipitation under aqueous ammon...Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction(ORR).However,they are usually synthesized through oxidation-precipitation under aqueous ammonia and then crystallization at high temperature(150–180℃),which not only increases the energy consumption but also induces the growth of particles that is unfavorable for ORR.Herein,through a facile precipitation-dehydration method,ultrasmall spinel manganese-cobalt oxide nanoparticles(~5 nm)homogeneously dispersed on conductive carbon black(MnxCo3-xO4/C)were fabricated at low temperature(60℃).And the bimetallic composite oxide(Mn1.5Co1.5O4/C)with cubic spinel structure and high Mn content exhibits remarkable enhancement of ORR activity and stability compared with single metal oxide(both Mn3O4/C and Co3O4/C).The essential reason for the enhancement of activity can be attributed to the presence of the mixed Mn^3+ and Mn^4+ cations in Mn1.5Co1.5O4/C.Moreover,the ORR activity of Mn1.5Co1.5O4/C is comparable to that of commercial 20 wt% Pt/C,and the relative current density only decreases 1.4% after 12 h test,exceeding that of Pt/C and most reported manganese-cobalt oxide electrocatalysts.展开更多
W-doped Li4TisO12 in the form of Li4Ti4.95W0.osO12 was firstly synthesized via solid state reaction. X-ray diffraction （XRD） and scanning electron microscope （gEM） were employed to characterize the structure and m...W-doped Li4TisO12 in the form of Li4Ti4.95W0.osO12 was firstly synthesized via solid state reaction. X-ray diffraction （XRD） and scanning electron microscope （gEM） were employed to characterize the structure and morphology of Li4Ti4.psW0.05Ol2. W-doping does not change the phase composition and particle morphology, while remarkably improves its cycling stability at high charge/discharge rate. Li4Ti4.95W0.05O12 exhibits an excellent rate capability with a reversible capacity of 131.2 mA.h/g at 10C and even 118.6 mA.h/g at 20C. The substitution of W for Ti site can enhance the electronic conductivity of Li4TisO12 via the generation of mixing Ti4＋/Ti3＋, which indicates that Li4Ti4.psW0.05O12 is promising as a high rate anode for the lithium-ion batteries.展开更多
There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,a...There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.展开更多
文摘In this paper, we report a new kind of moist chemical method for preparing LiNiVO 4 which can be used to prepare lithium ion battery for the cathode active materials with a very high battery voltage(48 V vs. Li). Li 2CO 3, NiCO 3 and NH 4VO 3 were used as row materials, and H 2C 2O 4 saturated solution was used both as a precipitate agent and as a complex agent. The precursor gel composed of (NH 4) 2(VO) 2(C 2O 4) 4·6H 2O, NiC 2O 4·2H 2O and Li 2C 2O 4 can be obtained, and after sintering the dry gel we got the products. The results of XRD show that the product sintered at 400 ℃ for 2 h exists in a cubic crystal, single phase, inverse LiNiVO 4 and the average sizes (by Scherrer formula ) were 40—50 nm(400 ℃, 2 h ) and 65—70 nm(700 ℃, 2 h) , respectively, a=0.822 3(1) nm. The TG and DTA curves implied that the dry gel underwent water loss, decompositions of oxalates and complex oxalate, the solid state reactions finished at 377 ℃. The results of XPS proved that the valence in LiNiVO 4 would be Li+,V 5+ , Ni 2+ (in the main), respectively. From ICP analysis we also knew that the sample corresponded basically to stoichiometry LiNiVO 4 .
文摘A robust oxygen‐related electrocatalyst,composed of spinel iron‐cobalt oxide and nitrogen‐dopedordered mesoporous carbon(NOMC),was developed for rechargeable metal‐air batteries.Electrochemicaltests revealed that the optimal catalyst Fe_(0.5)Co/NOMC exhibits superior activity with ahalf‐wave potential of 0.89 V(vs.reversible hydrogen electrode)for the oxygen reduction reactionand an overpotential of 0.31 V at 10 mA cm^(−2)for the oxygen evolution reaction.For demonstration,the catalyst was used in the assembly of a rechargeable zinc‐air battery,which exhibited an exceptionallyhigh energy density of 820 Wh kg−1 at 100 mA cm^(−2),a high power density of 153 mW cm^(−2)at1.0 V,and superior cycling stability up to 432 cycles(144 h)under ambient air.
基金supported by the National Key Basic Research Program of China (2016YFA0300102)the National Natural Science Foundation of China (No.11675179,No.U1532142,and No.11434009)the Fundamental Research Funds for the Central Universities
文摘Oxygen evolution reaction is one of the key processes in the promising renewable energy technique of electrocatalytic water splitting.Developing high ecient oxygen evolution reaction(OER)catalysts requires determination of the optimal values of the descriptor parameters.Using spinel CoFe2O4 as the model catalyst,this work demonstrates that irradiation with pulsed UV laser can control the quantity of surface oxygen vacancy and thus modify the OER activity,in a volcano-shape evolution trend.This strategy sheds light on quantita-tively investigation of the relationship between surface cation valence,anion vacancy,and physicochemical properties of transition-metal-based compounds.
基金Project(11264024)supported by the National Natural Science Foundation of ChinaProjects(2015MS0102,2015MS0524)supported by Natural Science Foundation of Inner Mongolia,China
文摘From the UV?Vis absorption spectra,the FT-IR absorption spectra and the Raman spectra,it is deduced that Co ionsprimarily occupy the tetrahedral(A)site,with a minor number of them entering into the octahedral(B)site in the Ni1?xCoxCr2O4compounds.The origin of the position disorder of the Co ions is consistent with the similar ionic radii of the Co ion(0.65?)and theCr ion(0.62?)at B site.The FT-IR peak at about510cm?1shifts towards high frequency side with the increasing cobalt content.Itis resulted from the reduction of the cation?oxygen distance in the octahedron by the replacement of the Ni2+with the Co2+ions.Themagnetic measurement shows that Curie temperatures(TC)are75and90K for the compounds with x=0.2and0.8,respectively.
文摘Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction(ORR).However,they are usually synthesized through oxidation-precipitation under aqueous ammonia and then crystallization at high temperature(150–180℃),which not only increases the energy consumption but also induces the growth of particles that is unfavorable for ORR.Herein,through a facile precipitation-dehydration method,ultrasmall spinel manganese-cobalt oxide nanoparticles(~5 nm)homogeneously dispersed on conductive carbon black(MnxCo3-xO4/C)were fabricated at low temperature(60℃).And the bimetallic composite oxide(Mn1.5Co1.5O4/C)with cubic spinel structure and high Mn content exhibits remarkable enhancement of ORR activity and stability compared with single metal oxide(both Mn3O4/C and Co3O4/C).The essential reason for the enhancement of activity can be attributed to the presence of the mixed Mn^3+ and Mn^4+ cations in Mn1.5Co1.5O4/C.Moreover,the ORR activity of Mn1.5Co1.5O4/C is comparable to that of commercial 20 wt% Pt/C,and the relative current density only decreases 1.4% after 12 h test,exceeding that of Pt/C and most reported manganese-cobalt oxide electrocatalysts.
文摘W-doped Li4TisO12 in the form of Li4Ti4.95W0.osO12 was firstly synthesized via solid state reaction. X-ray diffraction （XRD） and scanning electron microscope （gEM） were employed to characterize the structure and morphology of Li4Ti4.psW0.05Ol2. W-doping does not change the phase composition and particle morphology, while remarkably improves its cycling stability at high charge/discharge rate. Li4Ti4.95W0.05O12 exhibits an excellent rate capability with a reversible capacity of 131.2 mA.h/g at 10C and even 118.6 mA.h/g at 20C. The substitution of W for Ti site can enhance the electronic conductivity of Li4TisO12 via the generation of mixing Ti4＋/Ti3＋, which indicates that Li4Ti4.psW0.05O12 is promising as a high rate anode for the lithium-ion batteries.
文摘There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.
