Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Her...Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Herein,hollow oxygen deficiency-enriched NiFe_(2)O_(4) is synthesized by pyrolytic FeNi bimetallic MOF.The defects of rGO during carbonization can act as nucleation sites for FeNi particles.After nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO.These deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe_(2)O_(4) together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic activity.The resultant NiFe_(2)O_(4)@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^(-2) for OER and 157 mV at 10 mA cm^(-2) for HER in 1 M KOH,respectively.When used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^(-2),respectively.展开更多
Hypoxia challenges aerobic organisms in numerous environments,and hypoxic conditions may become more severe under future climate-change scenarios.The impact of hypoxia on the development of terrestrial insect embryos ...Hypoxia challenges aerobic organisms in numerous environments,and hypoxic conditions may become more severe under future climate-change scenarios.The impact of hypoxia on the development of terrestrial insect embryos is not well understood.Here,to address this gap,embryonic life-history traits of migratory locust Locusta migratoria from low-altitude and high-altitude regions were compared under 2 oxygen levels:normoxia(i.e.,21 kPa oxygen partial pressure and mild hypoxia(i.e.,10 kPa oxygen partial pressure).Our results demonstrated that,whether reared under normoxia or mild hypoxia,L.migratoria from high-altitude populations had longer developmental times,reduced weight,and lower mean relative growth rate as compared with those from low-altitude populations.When transferred from normoxia to mild hypoxia,nearly all the tested lifehistory traits presented significant negative changes in the low-altitude populations,but not in the high-altitude populations.The factor'strain'alone explained 18.26%-54.59%of the total variation for traits,suggesting that the phenotypic differences between L.migratoria populations from the 2 altitudes could be driven by genetic variation.Significant genetic correlations were found between life-history traits,and most of these showed differentiation between the 2 altitudinal gradients.G-matrix comparisons showed significant structural differences between L.migratoria from the 2 regions,as well as several negative covariances(i.e.,trade-offs)between traits in the low-altitude populations.Overall,our study provides clear evidence that evolutionary divergence of embryonic traits between L.migratoria populations from different altitudes has occurred.展开更多
Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still ...Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V_(2)O_(3)nanoparticles encapsulated in amorphous carbon shell(Od-V_(2)O_(3)@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V_(2)O_(3)@C electrode exhibits superior rate capability(reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and2000 mA/g, respectively), and ultralong cycle life(127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.展开更多
Sr2VO3-δFeAs superconductors with different oxygen deficiencies have been successfully fabricated.It is found that the superconducting transition temperature drops down monotonically with the increase of nominal oxyg...Sr2VO3-δFeAs superconductors with different oxygen deficiencies have been successfully fabricated.It is found that the superconducting transition temperature drops down monotonically with the increase of nominal oxygen deficiency.The diminishing of superconductivity is accompanied by the enhancement of residual resistivity,indicating an anomalous scattering effect induced by the oxygen deficiency.The highest superconducting transition temperature at about 36 K is achieved near the stoichiometrical sample Sr2VO2.9FeAs.The Hall effect measurements reveal that the density of charge carriers(electron-like here) varies qualitatively with the increase of nominal oxygen deficiency.Magnetotransport measurements show that the superconducting transition changes from one-step-like shape at low fields to two-step-like one at high fields,indicating an enhanced vortex motion due to the high anisotropy.展开更多
Novel black oxygen deficient bismuth oxide(Bi_(2)O_(3)-Bi_(2)O_(3-x))photocatalytic material was successfully prepared by a two zone temperature controlled muffle furnace method.The lanthanum,cerium and erbium ions ar...Novel black oxygen deficient bismuth oxide(Bi_(2)O_(3)-Bi_(2)O_(3-x))photocatalytic material was successfully prepared by a two zone temperature controlled muffle furnace method.The lanthanum,cerium and erbium ions are successfully doped into Bi_(2)O_(3)-Bi_(2)O_(3-x) with the average contents of 10.77 wt%,7.62 wt%and 8,14 wt%,respectively.The re sults show that a large number of oxygen vacancies exist in Bi_(2)O_(3)-Bi_(2)O_(3-x).La^(3+)Ce^(3+)and Er^(3+)act as electron acceptors to temporarily trap the photo-generated electrons.The XPS spectrum show Bi-O band in Bi_(2)O_(3)-Bi_(2)O_(3-x) and the O 1s peak of Ce/Bi_(2)O_(3)-Bi_(2)O_(3-x) move toward the direction of low binding energy.These phenomena fully prove that the separation of photogenerated electron-hole pairs will be more effectual,so as to reduce the possibility of charge carrier recombination.The radical scavenging experiments and electron spin resonance detections confirm that the conduction band of the original Bi_(2)O_(3)can easily receive photogenerated electrons,while the valence band of the modified Bi_(2)O_(3)-Bi_(2)O_(3-x) tends to accept photogenerated holes and then forms the circulation system.Therefore,Ce/Bi_(2)O_(3)-Bi_(2)O_(3-x) can degrade tetracycline hydrochloride up to 90.15%.This research provides some new insights into developing green and recyclable photocatalysts for the remediation of antibiotic contamination.展开更多
Cerium oxide(CeO_(2)),one of the most significant rare-earth oxides,has attracted considerable interest over the past decades.This is primarily due to the ease in Ce^(3+)/Ce^(4+)redox ability as well as other factors ...Cerium oxide(CeO_(2)),one of the most significant rare-earth oxides,has attracted considerable interest over the past decades.This is primarily due to the ease in Ce^(3+)/Ce^(4+)redox ability as well as other factors that affect the efficacy of CeO_(2)and CeO_(2)-based materials.CeO_(2)and CeO_(2)-based materials have shown enhanced responses in catalytic and photocatalytic activities for environmental and biological applications.In addition,the formation of Ce^(3+)and oxygen vacancies in CeO_(2)has aided in enhancing CeO_(2)activities.In order to produce oxygen-deficient CeO_(2)and CeO_(2)-based materials,a variety of synthesis methods were used and are highlighted in this review.Therefore,this review compiles and discusses the mechanisms that involve oxygen vacancies,defects,and Ce^(3+)formation for environmental applications,such as photocatalytic dye degradation,photocatalytic CO_(2)reduction,and non-colored pollutants removal.The biological applications of CeO_(2),such as antioxidant enzyme mimetic,antioxidant reactive oxygen species/reactive nitrogen species,and antimicrobial activities,are also discussed.Additionally,future prospects are also suggested for future development and detailed investigations.展开更多
The defect engineering shows great potential in boosting the conversion of lithium polysulfides intermediates for high energy density lithium-sulfur batteries(LSBs),yet the catalytic mechanisms remain unclear.Herein,t...The defect engineering shows great potential in boosting the conversion of lithium polysulfides intermediates for high energy density lithium-sulfur batteries(LSBs),yet the catalytic mechanisms remain unclear.Herein,the oxygen-defective Li_(4)Ti_(5)O_(12)-xhollow microspheres uniformly encapsulated by N-doped carbon layer(OD-LTO@NC)is delicately designed as an intrinsically polar inorganic sulfur host for the research on the catalytic mechanism.Theoretical simulations have demonstrated that the existence of oxygen deficiencies enhances the adsorption capability of spinel Li_(4)Ti_(5)O_(12)towards soluble lithium polysulfides.Some-S-S-bonds of the Li2S6on the defective Li_(4)Ti_(5)O_(12)surface are fractured by the strong adsorption force,which allows the inert bridging sulfur atoms to be converted into the susceptible terminal sulfur atoms,and reduces the activation energy of the polysulfide conversion in some degree.In addition,with the N-doped carbon layer,secondary hollow microspheres architecture built with primary ultrathin nanosheets provide a large amount of void space and active sites for sulfur storage,adsorption and conversion.The as-designed sulfur host exhibits a remarkable rate capability of 547 m Ah g^(-1)at 4C(1 C=1675 m A g^(-1))and an outstanding long-term cyclability(519 m Ah g^(-1)after 1000 cycles at 3 C).Besides,a high specific capacity of 832 m Ah g^(-1)is delivered even after 100 cycles under a high sulfur mass loading of 3.2 mg cm^(-2),indicating its superior electrochemical performances.This work not only provides a strong proof for the application of oxygen defect in the adsorption and catalytic conversion of lithium polysulfides,but offers a promising avenue to achieve high performance LSBs with the material design concept of incorporating oxygen-deficient spinel structure with hierarchical hollow frameworks.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21878231,21676202 and 51603145)Natural Science Foundation of Tianjin(Nos.19JCZDJC37300 and 17JCZDJC38100)supported by the Science and Technology Plans of Tianjin(Nos.17PTSYJC00040 and 18PTSYJC00180)。
文摘Bimetallic metal organic framework(MOF)as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)attracts more and more attention.Herein,hollow oxygen deficiency-enriched NiFe_(2)O_(4) is synthesized by pyrolytic FeNi bimetallic MOF.The defects of rGO during carbonization can act as nucleation sites for FeNi particles.After nucleation and N doping,the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO.These deposited carbon,like a bridge,connect N/rGO and hollow oxygen deficiency-enriched NiFe_(2)O_(4) together,which giving full play to the advantages of N/rGO in fast electron transfer,thereby improving its catalytic activity.The resultant NiFe_(2)O_(4)@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm^(-2) for OER and 157 mV at 10 mA cm^(-2) for HER in 1 M KOH,respectively.When used as bifunctional electrodes for overall water splitting,it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm^(-2),respectively.
基金the National Natural Science Foundation of China(No.32102208)the Natural Science Foundation of Hebei Province(No.C2021201052)a grant from Hebei University(No.521000981353).
文摘Hypoxia challenges aerobic organisms in numerous environments,and hypoxic conditions may become more severe under future climate-change scenarios.The impact of hypoxia on the development of terrestrial insect embryos is not well understood.Here,to address this gap,embryonic life-history traits of migratory locust Locusta migratoria from low-altitude and high-altitude regions were compared under 2 oxygen levels:normoxia(i.e.,21 kPa oxygen partial pressure and mild hypoxia(i.e.,10 kPa oxygen partial pressure).Our results demonstrated that,whether reared under normoxia or mild hypoxia,L.migratoria from high-altitude populations had longer developmental times,reduced weight,and lower mean relative growth rate as compared with those from low-altitude populations.When transferred from normoxia to mild hypoxia,nearly all the tested lifehistory traits presented significant negative changes in the low-altitude populations,but not in the high-altitude populations.The factor'strain'alone explained 18.26%-54.59%of the total variation for traits,suggesting that the phenotypic differences between L.migratoria populations from the 2 altitudes could be driven by genetic variation.Significant genetic correlations were found between life-history traits,and most of these showed differentiation between the 2 altitudinal gradients.G-matrix comparisons showed significant structural differences between L.migratoria from the 2 regions,as well as several negative covariances(i.e.,trade-offs)between traits in the low-altitude populations.Overall,our study provides clear evidence that evolutionary divergence of embryonic traits between L.migratoria populations from different altitudes has occurred.
基金financial support from the National Natural Science Foundation of China(Nos.51922042 and 51872098)Fundamental Research Funds for Central Universities,China(No.2020ZYGXZR074)the Scientific and Technological Plan of Qingyuan City,China(2019DZX008)。
文摘Potassium ion batteries(PIBs) have been regarded as promising alternatives to lithium ion batteries(LIBs)on account of their abundant resource and low cost in large scale energy storage applications. However,it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V_(2)O_(3)nanoparticles encapsulated in amorphous carbon shell(Od-V_(2)O_(3)@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V_(2)O_(3)@C electrode exhibits superior rate capability(reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and2000 mA/g, respectively), and ultralong cycle life(127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.
基金supported by the National Natural Science Foundation of China,the National Basic Research Program of China (Grant Nos. 2006CB601000 and 2006CB921802)the Chinese Academy of Sciences Project (Grant No. ITSNEM)
文摘Sr2VO3-δFeAs superconductors with different oxygen deficiencies have been successfully fabricated.It is found that the superconducting transition temperature drops down monotonically with the increase of nominal oxygen deficiency.The diminishing of superconductivity is accompanied by the enhancement of residual resistivity,indicating an anomalous scattering effect induced by the oxygen deficiency.The highest superconducting transition temperature at about 36 K is achieved near the stoichiometrical sample Sr2VO2.9FeAs.The Hall effect measurements reveal that the density of charge carriers(electron-like here) varies qualitatively with the increase of nominal oxygen deficiency.Magnetotransport measurements show that the superconducting transition changes from one-step-like shape at low fields to two-step-like one at high fields,indicating an enhanced vortex motion due to the high anisotropy.
基金Project supported by the National Natural Science Foundation of China(51966003)Innovation Project of Guangxi Graduate Education(YCBZ2020065)Natural Science Foundation of Guangxi Province(2018GXNSFDA050004)。
文摘Novel black oxygen deficient bismuth oxide(Bi_(2)O_(3)-Bi_(2)O_(3-x))photocatalytic material was successfully prepared by a two zone temperature controlled muffle furnace method.The lanthanum,cerium and erbium ions are successfully doped into Bi_(2)O_(3)-Bi_(2)O_(3-x) with the average contents of 10.77 wt%,7.62 wt%and 8,14 wt%,respectively.The re sults show that a large number of oxygen vacancies exist in Bi_(2)O_(3)-Bi_(2)O_(3-x).La^(3+)Ce^(3+)and Er^(3+)act as electron acceptors to temporarily trap the photo-generated electrons.The XPS spectrum show Bi-O band in Bi_(2)O_(3)-Bi_(2)O_(3-x) and the O 1s peak of Ce/Bi_(2)O_(3)-Bi_(2)O_(3-x) move toward the direction of low binding energy.These phenomena fully prove that the separation of photogenerated electron-hole pairs will be more effectual,so as to reduce the possibility of charge carrier recombination.The radical scavenging experiments and electron spin resonance detections confirm that the conduction band of the original Bi_(2)O_(3)can easily receive photogenerated electrons,while the valence band of the modified Bi_(2)O_(3)-Bi_(2)O_(3-x) tends to accept photogenerated holes and then forms the circulation system.Therefore,Ce/Bi_(2)O_(3)-Bi_(2)O_(3-x) can degrade tetracycline hydrochloride up to 90.15%.This research provides some new insights into developing green and recyclable photocatalysts for the remediation of antibiotic contamination.
基金the FRC grant(UBD/RSCH/1.4/FICBF(b)/2022/046)received from Universiti Brunei Darussalam,Brunei Darussalam。
文摘Cerium oxide(CeO_(2)),one of the most significant rare-earth oxides,has attracted considerable interest over the past decades.This is primarily due to the ease in Ce^(3+)/Ce^(4+)redox ability as well as other factors that affect the efficacy of CeO_(2)and CeO_(2)-based materials.CeO_(2)and CeO_(2)-based materials have shown enhanced responses in catalytic and photocatalytic activities for environmental and biological applications.In addition,the formation of Ce^(3+)and oxygen vacancies in CeO_(2)has aided in enhancing CeO_(2)activities.In order to produce oxygen-deficient CeO_(2)and CeO_(2)-based materials,a variety of synthesis methods were used and are highlighted in this review.Therefore,this review compiles and discusses the mechanisms that involve oxygen vacancies,defects,and Ce^(3+)formation for environmental applications,such as photocatalytic dye degradation,photocatalytic CO_(2)reduction,and non-colored pollutants removal.The biological applications of CeO_(2),such as antioxidant enzyme mimetic,antioxidant reactive oxygen species/reactive nitrogen species,and antimicrobial activities,are also discussed.Additionally,future prospects are also suggested for future development and detailed investigations.
基金supported by the National Natural Science Foundation of China(21805157,51972187)Natural Science Foundation of Shandong Province(ZR2019MEM043,ZR2019MB037)+1 种基金Shandong Provincial Key Research and Development Program(2019GGX103034)Development Program in Science and Technology of Qingdao(19-6-2-12-cg)。
文摘The defect engineering shows great potential in boosting the conversion of lithium polysulfides intermediates for high energy density lithium-sulfur batteries(LSBs),yet the catalytic mechanisms remain unclear.Herein,the oxygen-defective Li_(4)Ti_(5)O_(12)-xhollow microspheres uniformly encapsulated by N-doped carbon layer(OD-LTO@NC)is delicately designed as an intrinsically polar inorganic sulfur host for the research on the catalytic mechanism.Theoretical simulations have demonstrated that the existence of oxygen deficiencies enhances the adsorption capability of spinel Li_(4)Ti_(5)O_(12)towards soluble lithium polysulfides.Some-S-S-bonds of the Li2S6on the defective Li_(4)Ti_(5)O_(12)surface are fractured by the strong adsorption force,which allows the inert bridging sulfur atoms to be converted into the susceptible terminal sulfur atoms,and reduces the activation energy of the polysulfide conversion in some degree.In addition,with the N-doped carbon layer,secondary hollow microspheres architecture built with primary ultrathin nanosheets provide a large amount of void space and active sites for sulfur storage,adsorption and conversion.The as-designed sulfur host exhibits a remarkable rate capability of 547 m Ah g^(-1)at 4C(1 C=1675 m A g^(-1))and an outstanding long-term cyclability(519 m Ah g^(-1)after 1000 cycles at 3 C).Besides,a high specific capacity of 832 m Ah g^(-1)is delivered even after 100 cycles under a high sulfur mass loading of 3.2 mg cm^(-2),indicating its superior electrochemical performances.This work not only provides a strong proof for the application of oxygen defect in the adsorption and catalytic conversion of lithium polysulfides,but offers a promising avenue to achieve high performance LSBs with the material design concept of incorporating oxygen-deficient spinel structure with hierarchical hollow frameworks.
