Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In...Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In this work,we investigated the effect of corrosion product film layers on the degradation behavior of pure Mg in physiological environments.Pure Mg shows a faster corrosion rate in simulated body fluid(SBF)compared to NaCl solution.Hydrogen evolution experiments indicate that the degradation rate of pure Mg in SBF decreases rapidly within the first 12 h but stabilizes afterward.The rapid deposition of low-solubility calcium phosphate on the pure Mg in SBF provides protection to the substrate,resulting in a gradual decrease in the degradation rates.Consequently,the corrosion product film of pure Mg formed in SBF exhibits a layered structure,with the upper layer consisting of dense Ca_(3)(PO_(4))_(2)/Mg_(3)(PO_(4))_(2) and the lower layer consisting of Mg(OH)_(2)/MgO.Electrochemical impedance spectroscopy(EIS)shows that the resistance of the corrosion product film increases over time,indicating gradual strengthening of the corrosion resistance.The 4-week degradation results in the femoral marrow cavity of mice are consistent with the result in SBF in vitro.展开更多
Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corros...Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corrosion resistance.In this work,polyhydroxybutyrate(PHB) coatings are deposited on Mg sheets with a thickness similar to that of cardiovascular stents to assess the degradation behavior,and poly-lactic acid(PLA)-coated Mg is also investigated to compare the structure-propertyperformance relationship.The hydrogen evolution volume(HEV) of the PHB-coated sample decreases by 30% after immersion in artificial blood plasma(AP) for 7 days,whereas the PL A-coated sample shows an increase of 154%.The PHB coating also shows excellent durability at a constant voltage,compared to severe rupture of the PLA coating.The degradation behavior of the coated-Mg samples is evaluated in AP solution containing different concentrations of the bovine serum albumin(BSA).Corrosion is inhibited as the protein concentration increases.The degradation rates of the Mg,PLA-coated Mg,and PHBcoated Mg decrease by 65%,88%,and 75% for 5 g L^(-1)BSA,respectively.Our results reveal that higher crystallinity and less acidic degradation products give rise to better durability,while the acid self-catalytic effect leads to the failure of PLA.The protein-polymer interactions are determined and the empirical relationship of HEV is established.展开更多
Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline el...Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.展开更多
Antimony(Sb)is regarded as a potential candidate for next-generation anode materials for rechargeable batteries because it has a high theoretical specific capacity,excellent conductivity and appropriate reaction poten...Antimony(Sb)is regarded as a potential candidate for next-generation anode materials for rechargeable batteries because it has a high theoretical specific capacity,excellent conductivity and appropriate reaction potential.However,Sb-based anodes suffer from severe volume expansion of>135%during the lithiation-delithiation process.Hence,we construct a novel Sb@C composite encapsulating the Sb nanoparticles into highly conductive three-dimensional porous carbon frameworks via the one-step magnesiothermic reduction(MR).The porous carbon provides buffer spaces to accommodate the volume expansion of Sb.Meanwhile,the three-dimensional(3D)interconnected carbon frameworks shorten the ion/electron transport pathway and inhibit the overgrowth of unstable solid-electrolyte interfaces(SEIs).Consequently,the 3D Sb@C composite displays remarkable electrochemical performance,including a high average Coulombic efficiency(CE)of>99%,high initial capability of 989 mAh·g^(-1),excellent cycling stability for over 1000 cycles at a high current density of 5 A·g^(-1).Furthermore,employing a similar approach,this 3D Sb@C design paradigm holds promise for broader applications across fast-charging and ultralong-life battery systems beyond Li+.This work aims to advance practical applications for Sb-based anodes in next-generation batteries.展开更多
研究了在 Co/Ti/Si结构中加入非晶 Ge Si层对 Co Si2 /Si异质固相外延的影响 ,用离子束溅射方法在Si衬底上制备 Co/Ge Si/Ti/Si结构多层薄膜 ,通过快速热退火使多层薄膜发生固相反应。采用四探针电阻仪、AES、XRD、RBS等方法进行测试。...研究了在 Co/Ti/Si结构中加入非晶 Ge Si层对 Co Si2 /Si异质固相外延的影响 ,用离子束溅射方法在Si衬底上制备 Co/Ge Si/Ti/Si结构多层薄膜 ,通过快速热退火使多层薄膜发生固相反应。采用四探针电阻仪、AES、XRD、RBS等方法进行测试。实验表明 ,利用 Co/Ge Si/Ti/Si固相反应形成的 Co Si2 薄膜具有良好的外延特性和电学特性 ,Ti中间层和非晶 Ge Si中间层具有促进和改善 Co Si2 外延质量 ,减少衬底耗硅量的作用。Ge原子的存在能够改善外延 Co Si2展开更多
Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.Ho...Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.However,fabrication of porous structures tends to be difficult to control and complex,so,the final electrochemical performance can be compromised.Herein,a modest magnesiothermic reduction(MMR)reaction is demonstrated to produce blackberry-like porous Si nanospheres(PSSs)controllably using magnesium silicide(Mg_(2)Si)as Mg source and SiO_(2)nanospheres as the reactant.This improved MR method provides good control of the kinetics and heat release compared to the traditional MR(TMR)method using Mg powder as the reactant.The PSSs obtained by MMR reaction has higher structural integrity than that fabricated by TMR.After encapsulation with reduced graphene oxide,the Si/C composite exhibits superior cycling stability and rates such as a high reversible capacity of 1034 mAh·g^(-1)at0.5 C(4200 mAh·g^(-1)at 1.0 C)after 1000 cycles,capacity retention of 79.5%,and high rate capacity of 497 mAh·g^(-1)at 2.0 C.This strategy offers a new route to fabricate highperformance porous Si anodes and can be extended to other materials such as germanium.展开更多
Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusio...Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.展开更多
Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer ...Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion.The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification.Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization,and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus,human lung epithelial cancer cells(A549),as well as human endothelial cells(EA.hy926).The nanoporous layer with a thickness of 10.1 lm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells.Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells.The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.展开更多
Flexible quasi-solid zinc-ion batteries(ZIBs)have large potential in power applications due to the low price,wearable nature,safety,and high capacity.However,the use of transition metal sulfide cathodes in ZIBs has no...Flexible quasi-solid zinc-ion batteries(ZIBs)have large potential in power applications due to the low price,wearable nature,safety,and high capacity.However,the use of transition metal sulfide cathodes in ZIBs has not been studied extensively and the underlying mechanism and theoretical basis of this type of batteries are not well understood.Herein,a highly active cobalt-doped Ni_(3)S_(2) porous nanocone framework(C12NS)is designed and demonstrated as a zinc-ion battery electrode.First-principles calculation and experiments reveal that the cobalt dopant improves the battery properties greatly.The assembled flexible zinc-ion battery exhibits a high specific capacity of 453.3 mAh g^(−1)at a current density of 0.4 A g^(−1)in as well as excellent cycling stability as manifested by a capacity retention ratio of 89.5%at a current density of 4 A g^(−1)after 5000 cycles.The peak energy density of 553.9 Wh kg^(−1)is also superior to those of most recently reported NiCo-based zinc-ion batteries.More importantly,the flexible battery can be operated under severe mechanical bending and even continues to work after physical puncturing without showing leakage.These exciting results not only reveal a novel design of cathode materials for zinc-based batteries,but also suggest their immense commercial potential in portable and wearable electronics.展开更多
Although Ni-Ti-O nanopores(NPs) can be fabricated by anodization of mechanically polished NiTi alloys, the top disordered layer is difficult to remove thus hindering the functionality of the Ni-Ti-O NPs. In this work,...Although Ni-Ti-O nanopores(NPs) can be fabricated by anodization of mechanically polished NiTi alloys, the top disordered layer is difficult to remove thus hindering the functionality of the Ni-Ti-O NPs. In this work, an electropolishing(EP) pretreatment was performed on the NiTi substrate prior to anodization to thoroughly expose the NPs. Our results show that the EP pretreatment for 5 min perfectly removes the top disordered layer on the Ni-Ti-O NPs to expose the underlying NPs and consequently, the corrosion resistance and antibacterial ability are enhanced. The exposed NPs can elongate bone marrow mesenchymal stem cells, which may be responsible for the upregulated alkaline phosphatase activity, secretion of Type I collagen, and extracellular matrix mineralization. These results suggest that EP is a desirable pretreatment before anodization of the NiTi alloys because the irregular surface layer on the Ni-Ti-O NPs can be removed to enhance the corrosion resistance and biological functions.展开更多
Developing highly efficient catalysts for the hydrogen evolution reaction(HER)is crucial to commercial water splitting in the global efforts to mitigate fossil fuel combustion and combat global climate change.Molybden...Developing highly efficient catalysts for the hydrogen evolution reaction(HER)is crucial to commercial water splitting in the global efforts to mitigate fossil fuel combustion and combat global climate change.Molybdenum nitrides(Mo_(x)N)such asγ-Mo_(2)N andδ-MoN are promising HER catalysts.Althoughδ-MoN has better HER charac-teristics.展开更多
基金supported by the National Natural Science Foundation of China(52127801)Postdoctoral Fellowship Program of CPSF under Grant Number GZC20231545,China Postdoctoral Science Foundation(2024T170557 and 2023M742224)+1 种基金Shanghai Post-doctoral Excellence Program(No.2023440)City University of Hong Kong Donation Grants(DON-RMG No.9229021 and 9220061).
文摘Pure Mg boasting a relatively small corrosion rate is a potential biodegradable metal material for implants.However,its degradation behavior in the complex physiological environment is still a lack of understanding.In this work,we investigated the effect of corrosion product film layers on the degradation behavior of pure Mg in physiological environments.Pure Mg shows a faster corrosion rate in simulated body fluid(SBF)compared to NaCl solution.Hydrogen evolution experiments indicate that the degradation rate of pure Mg in SBF decreases rapidly within the first 12 h but stabilizes afterward.The rapid deposition of low-solubility calcium phosphate on the pure Mg in SBF provides protection to the substrate,resulting in a gradual decrease in the degradation rates.Consequently,the corrosion product film of pure Mg formed in SBF exhibits a layered structure,with the upper layer consisting of dense Ca_(3)(PO_(4))_(2)/Mg_(3)(PO_(4))_(2) and the lower layer consisting of Mg(OH)_(2)/MgO.Electrochemical impedance spectroscopy(EIS)shows that the resistance of the corrosion product film increases over time,indicating gradual strengthening of the corrosion resistance.The 4-week degradation results in the femoral marrow cavity of mice are consistent with the result in SBF in vitro.
基金jointly supported by the National Natural Science Foundation of China(No.52171236)State Key Program of the National Natural Science Foundation of China(No.52231005)+5 种基金Open Research Fund of Jiangsu Key Laboratory for Advanced Metallic Materials,Southeast University(No.AMM2024A01)Suzhou Science and Technology Project(Nos.SJC2023005 and SZS2023023)City University of Hong Kong Donation Research Grants(Nos.DON-RMG 9229021 and 9220061)Hong Kong Innovation and Technology Fund(Nos.ITF GHP/212/22GD and CityU 440399)Hong Kong PDFS_RGC Postdoctoral Fellowship Scheme(Nos.PDFS2122-1S08 and CityU 9061014)Hong Kong HMRF(Health and Medical Research Fund)(Nos.2120972 and CityU 9211320)
文摘Biodegradable polymer coatings are commonly used as protective barriers on magnesium(Mg) and its alloys.The properties of polymers,such as crystallinity and degradation properties,have a crucial impact on their corrosion resistance.In this work,polyhydroxybutyrate(PHB) coatings are deposited on Mg sheets with a thickness similar to that of cardiovascular stents to assess the degradation behavior,and poly-lactic acid(PLA)-coated Mg is also investigated to compare the structure-propertyperformance relationship.The hydrogen evolution volume(HEV) of the PHB-coated sample decreases by 30% after immersion in artificial blood plasma(AP) for 7 days,whereas the PL A-coated sample shows an increase of 154%.The PHB coating also shows excellent durability at a constant voltage,compared to severe rupture of the PLA coating.The degradation behavior of the coated-Mg samples is evaluated in AP solution containing different concentrations of the bovine serum albumin(BSA).Corrosion is inhibited as the protein concentration increases.The degradation rates of the Mg,PLA-coated Mg,and PHBcoated Mg decrease by 65%,88%,and 75% for 5 g L^(-1)BSA,respectively.Our results reveal that higher crystallinity and less acidic degradation products give rise to better durability,while the acid self-catalytic effect leads to the failure of PLA.The protein-polymer interactions are determined and the empirical relationship of HEV is established.
基金financially supported by the National Natural Science Foundation of China(No.U2004210)Application Foundation Frontier Project of Wuhan Science and Technology Program(No.2020010601012199)City University of Hong Kong Strategic Research Grant,Hong Kong,China(No.7005505)。
文摘Vanadium nitride(VN)is a promising pseudocapacitive material due to the high theoretical capacity,rapid redox Faradaic kinetics,and appropriate potential window.Although VN shows large pseudocapacitance in alkaline electrolytes,the electrochemical instability and capacity degradation of VN electrode materials present significant challenges for practical applications.Herein,the capacitance decay mechanism of VN is investigated and a simple strategy to improve cycling stability of VN supercapacitor electrodes is proposed by introducing VO_(4)^(3-)anion in KOH electrolytes.Our results show that the VN electrode is electrochemical stabilization between-1.0and-0.4 V(vs.Hg/Hg O reference electrode)in 1.0 MKOH electrolyte,but demonstrates irreversible oxidation and fast capacitance decay in the potential range of-0.4 to0 V.In situ electrochemical measurements reveal that the capacitance decay of VN from-0.4 to 0 V is ascribed to the irreversible oxidation of vanadium(V)of N–V–O species by oxygen(O)of OH^(-).The as-generated oxidization species are subsequently dissolved into KOH electrolytes,thereby undermining the electrochemical stability of VN.However,this irreversible oxidation process could be hindered by introducing VO_(4)^(3-)in KOH electrolytes.A high volumetric specific capacitance of671.9 F.cm^(-3)(1 A.cm^(-3))and excellent cycling stability(120.3%over 1000 cycles)are achieved for VN nanorod electrode in KOH electrolytes containing VO_(4)^(3-).This study not only elucidates the failure mechanism of VN supercapacitor electrodes in alkaline electrolytes,but also provides new insights into enhancing pseudocapacitive energy storage of VN-based electrode materials.
基金supported by the National Natural Science Foundation of China(No.22309056)the National Key R&.D Program of China(No.2022YFB2404800)+4 种基金the Basic Research Program of Shenzhen Municipal Science and Technology Innovation Committee(No.JCYJ20210324141613032)the Knowledge Innovation Project of Wuhan City(No.2022010801010303)the City University of Hong Kong Strategic Research Grant(SRG),Hong Kong,China(No.7005505)the City University of Hong Kong Donation Research Grant,Hong Kong,China(No.DON-RMG 9229021)the Postdoctoral Fellowship Program of CPSF(No.GZB20230552).
文摘Antimony(Sb)is regarded as a potential candidate for next-generation anode materials for rechargeable batteries because it has a high theoretical specific capacity,excellent conductivity and appropriate reaction potential.However,Sb-based anodes suffer from severe volume expansion of>135%during the lithiation-delithiation process.Hence,we construct a novel Sb@C composite encapsulating the Sb nanoparticles into highly conductive three-dimensional porous carbon frameworks via the one-step magnesiothermic reduction(MR).The porous carbon provides buffer spaces to accommodate the volume expansion of Sb.Meanwhile,the three-dimensional(3D)interconnected carbon frameworks shorten the ion/electron transport pathway and inhibit the overgrowth of unstable solid-electrolyte interfaces(SEIs).Consequently,the 3D Sb@C composite displays remarkable electrochemical performance,including a high average Coulombic efficiency(CE)of>99%,high initial capability of 989 mAh·g^(-1),excellent cycling stability for over 1000 cycles at a high current density of 5 A·g^(-1).Furthermore,employing a similar approach,this 3D Sb@C design paradigm holds promise for broader applications across fast-charging and ultralong-life battery systems beyond Li+.This work aims to advance practical applications for Sb-based anodes in next-generation batteries.
文摘研究了在 Co/Ti/Si结构中加入非晶 Ge Si层对 Co Si2 /Si异质固相外延的影响 ,用离子束溅射方法在Si衬底上制备 Co/Ge Si/Ti/Si结构多层薄膜 ,通过快速热退火使多层薄膜发生固相反应。采用四探针电阻仪、AES、XRD、RBS等方法进行测试。实验表明 ,利用 Co/Ge Si/Ti/Si固相反应形成的 Co Si2 薄膜具有良好的外延特性和电学特性 ,Ti中间层和非晶 Ge Si中间层具有促进和改善 Co Si2 外延质量 ,减少衬底耗硅量的作用。Ge原子的存在能够改善外延 Co Si2
基金Joint Project of Guangdong Province and Ministry of Education of China(2007A090302087)City University of HongKong Applied Research Grant(ARG)(9667028)
基金the National Natural Science Foundation of China(Nos.51974208 and51504171)the Major Project of Technology Innovation of Hubei Province(No.2018AAA011)+4 种基金the Special Project of Central Government for Local Science and Technology Development of Hubei Province(No.2019ZYYD024)the Innovation Group of Natural Science Foundation of Hubei Province(No.2019CFA020)Wuhan Yellow Crane Talents ProgramCity University of Hong Kong Applied Research Grant(ARG)(No.9667122)Hong Kong Research Grants Council(RGC)General Research Funds(GRF)(No.City U 11205617)。
文摘Porous silicon(Si)nanostructures have aroused much interest as lithium-ion battery anodes because of the large space to accommodate the volume change in lithiation and delithiation and shorter ion transfer distance.However,fabrication of porous structures tends to be difficult to control and complex,so,the final electrochemical performance can be compromised.Herein,a modest magnesiothermic reduction(MMR)reaction is demonstrated to produce blackberry-like porous Si nanospheres(PSSs)controllably using magnesium silicide(Mg_(2)Si)as Mg source and SiO_(2)nanospheres as the reactant.This improved MR method provides good control of the kinetics and heat release compared to the traditional MR(TMR)method using Mg powder as the reactant.The PSSs obtained by MMR reaction has higher structural integrity than that fabricated by TMR.After encapsulation with reduced graphene oxide,the Si/C composite exhibits superior cycling stability and rates such as a high reversible capacity of 1034 mAh·g^(-1)at0.5 C(4200 mAh·g^(-1)at 1.0 C)after 1000 cycles,capacity retention of 79.5%,and high rate capacity of 497 mAh·g^(-1)at 2.0 C.This strategy offers a new route to fabricate highperformance porous Si anodes and can be extended to other materials such as germanium.
基金This work was financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2020B1515120078,2021A1515111140,and 2021B1515120059)National Key Research and Development Project of China(No.2020YFC1107202)+3 种基金Science Research Cultivation Program(PY2022002)Science and Technology Planning Project of Guangzhou(No.202206010030)City University of Hong Kong Donation Research Grants[DONRMG No.9229021 and 9220061]as well as City University of Hong Kong Strategic Research Grant[SRG 7005505].
文摘Biodegradable metals such as magnesium(Mg)and its alloys have attracted extensive attention in biomedical research due to their excellent mechanical properties and biodegradability.However,traditional casting,extrusion,and commercial processing have limitations in manufacturing components with a complex shape/structure,and these processes may produce defects such as cavities and gas pores which can degrade the properties and usefulness of the products.Compared to conventional techniques,additive manufacturing(AM)can be used to precisely control the geometry of workpieces made of different Mg-based materials with multiple geometric scales and produce desirable medical products for orthopedics,dentistry,and other fields.However,a detailed and thorough understanding of the raw materials,manufacturing processes,properties,and applications is required to foster the production of commercial Mg-based biomedical components by AM.This review summarizes recent advances and important issues pertaining to AM of Mg-based biomedical products and discusses future development and application trends.
基金This study was financially supported by the Fund for Shanxi"1331 Project"Key Innovative Research Team(No.PY201809)the Natural Science Foundation of Shanxi Province(No.201801D121093)Hong Kong Research Grants Council General Research Funds(No.CityU 11205617).
文摘Stents made of nearly equiatomic NiTi alloy are used to treat malignant obstruction caused by cancer,but prevention of re-obstruction after surgery is still a challenge because the bare stents possess poor anticancer and antibacterial properties to inhibit cancer/bacteria invasion.The present work aims at endowing the NiTi alloy with anticancer and antibacterial abilities by surface modification.Ni–Ti–O nanoporous layers with different thicknesses were prepared on NiTi by anodization,and biological experiments were conducted to evaluate the effects on gram-positive Staphylococcus aureus,human lung epithelial cancer cells(A549),as well as human endothelial cells(EA.hy926).The nanoporous layer with a thickness of 10.1 lm inhibits growth of cancer cells and kill bacteria but shows little adverse effects on normal cells.Such selectivity is related to the larger amount of Ni ions leached from the sample in the acidic microenvironment of cancer cells in comparison with normal cells.The Ni–Ti–O nanoporous layers are promising as coatings on NiTi stents to prevent re-obstruction after surgery.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.61176108 and 61774060)the Science and Technology Commission of Shanghai Municipality(Grant No.18DZ2270800)+1 种基金the City University of Hong Kong Strategic Research Grant(SRG)(Grant No.7005505)the support of the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry(Grant No.[2015]-1098)。
文摘Flexible quasi-solid zinc-ion batteries(ZIBs)have large potential in power applications due to the low price,wearable nature,safety,and high capacity.However,the use of transition metal sulfide cathodes in ZIBs has not been studied extensively and the underlying mechanism and theoretical basis of this type of batteries are not well understood.Herein,a highly active cobalt-doped Ni_(3)S_(2) porous nanocone framework(C12NS)is designed and demonstrated as a zinc-ion battery electrode.First-principles calculation and experiments reveal that the cobalt dopant improves the battery properties greatly.The assembled flexible zinc-ion battery exhibits a high specific capacity of 453.3 mAh g^(−1)at a current density of 0.4 A g^(−1)in as well as excellent cycling stability as manifested by a capacity retention ratio of 89.5%at a current density of 4 A g^(−1)after 5000 cycles.The peak energy density of 553.9 Wh kg^(−1)is also superior to those of most recently reported NiCo-based zinc-ion batteries.More importantly,the flexible battery can be operated under severe mechanical bending and even continues to work after physical puncturing without showing leakage.These exciting results not only reveal a novel design of cathode materials for zinc-based batteries,but also suggest their immense commercial potential in portable and wearable electronics.
基金financially supported by the Fund for Shanxi ‘‘1331 Project’’ Key Innovative Research Team (No.PY201809)the Program for the Innovative Talents of Higher Education Institutions of Shanxi (PTIT)+1 种基金the Natural Science Foundation of Shanxi Province (No. 201801D121093)Hong Kong Research Grant Council (RGC) General Research Funds (GRF)(No. City U11205617)。
文摘Although Ni-Ti-O nanopores(NPs) can be fabricated by anodization of mechanically polished NiTi alloys, the top disordered layer is difficult to remove thus hindering the functionality of the Ni-Ti-O NPs. In this work, an electropolishing(EP) pretreatment was performed on the NiTi substrate prior to anodization to thoroughly expose the NPs. Our results show that the EP pretreatment for 5 min perfectly removes the top disordered layer on the Ni-Ti-O NPs to expose the underlying NPs and consequently, the corrosion resistance and antibacterial ability are enhanced. The exposed NPs can elongate bone marrow mesenchymal stem cells, which may be responsible for the upregulated alkaline phosphatase activity, secretion of Type I collagen, and extracellular matrix mineralization. These results suggest that EP is a desirable pretreatment before anodization of the NiTi alloys because the irregular surface layer on the Ni-Ti-O NPs can be removed to enhance the corrosion resistance and biological functions.
基金financially supported by Hong Kong Scholars Program(No.XJ2018009)City University of Hong Kong Strategic Research Grant(SRG)(No.7005505)+3 种基金City University of Hong Kong Donation Research Grant(No.9229021)the National Natural Science Foundation of China(No.52003129)Shandong Provincial Natural Science Foundation,China(No.ZR2019BB006)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China。
文摘Developing highly efficient catalysts for the hydrogen evolution reaction(HER)is crucial to commercial water splitting in the global efforts to mitigate fossil fuel combustion and combat global climate change.Molybdenum nitrides(Mo_(x)N)such asγ-Mo_(2)N andδ-MoN are promising HER catalysts.Althoughδ-MoN has better HER charac-teristics.
