Developing an e cient and durable oxygen reduction electrocatalyst is critical for clean-energy technology, such as fuel cells and metal–air batteries. In this study, we developed a facile strategy for the preparatio...Developing an e cient and durable oxygen reduction electrocatalyst is critical for clean-energy technology, such as fuel cells and metal–air batteries. In this study, we developed a facile strategy for the preparation of flexible, porous, and well-dispersed metal–heteroatom-doped carbon nanofibers by direct carbonization of electrospun Zn/Co-ZIFs/PAN nanofibers(Zn/Co-ZIFs/PAN). The obtained Zn/Co and N co-doped porous carbon nanofibers carbonized at 800 °C(Zn/Co–N@PCNFs-800) presented a good flexibility, a continuous porous structure, and a superior oxygen reduction reaction(ORR) catalytic activity to that of commercial 20 wt% Pt/C, in terms of its onset potential(0.98 V vs. RHE), half-wave potential(0.89 V vs. RHE), and limiting current density(-5.26 mA cm^(-2)). In addition, we tested the suitability and durability of Zn/Co–N@PCNFs-800 as the oxygen cathode for a rechargeable Zn–air battery. The prepared Zn–air batteries exhibited a higher power density(83.5 mW cm^(-2)), a higher specific capacity(640.3 mAh g^(-1)), an excellent reversibility, and a better cycling life than the commercial 20 wt% Pt/C + RuO_2 catalysts. This design strategy of flexible porous non-precious metal-doped ORR electrocatalysts obtained from electrospun ZIFs/polymer nanofibers could be extended to fabricate other novel, stable, and easy-to-use multi-functional electrocatalysts for clean-energy technology.展开更多
Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphox...Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphoxide self-standing electrode(CNFMPO)is synthesized by the facile and fast electrodeposition method.CNFMPO exhibits excellent bifunctional electrocatalytic performances on alkaline water/seawater electrolysis.The hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)overpotentials of CNFMPO in alkaline water/seawater are as low as 43/73 and 252/282 mV to reach a current density of 10 mA cm^(-2),respectively.Additionally,two-electrode electrolyzers with CNFMPO||CNFMPO successfully achieve the current density of 10 mA cm^(-2) at low voltages of 1.54 and 1.56 V for overall alkaline water/seawater splitting,respectively.CNFMPO exhibits satisfactory long-term stability on overall alkaline water/seawater splitting for the surface reconstruction into active metal hydroxide/(oxy)hydroxide,phosphite,and phosphate.Moreover,no hypochlorite is detected during seawater electrolysis for the beneficial chlorite oxidation inhibition of the reconstructed phosphite and phosphate.The excellent catalytic performances of CNFMPO are due to the unique amorphous structure,multi-component synergistic effect,beneficial electronic structure modulation,and surface reconstruction during the catalytic reaction process.Therefore,CNFMPO has shown potential promotion to the development of the water/seawater splitting industry as a promising substituent for noble-metal electrocatalysts.This work provides new insights into the design of efficient bifunctional catalysts for overall water/seawater splitting.展开更多
Seawater electrolysis is one most promising development directions for future hydrogen energy.How-ever,big challenges of active site poisoning,chloride oxidation(ClOR),and chloride corrosion on anode electrocatalysts,...Seawater electrolysis is one most promising development directions for future hydrogen energy.How-ever,big challenges of active site poisoning,chloride oxidation(ClOR),and chloride corrosion on anode electrocatalysts,seriously impede seawater electrolysis development.Therefore,developing efficient an-odic oxygen evolution reaction(OER)electrocatalysts is an urgent task for seawater electrolysis.The ad-vanced strategies of improving OER kinetics,lowering ClOR kinetics,strengthening corrosion resistance,and recombining multifunction are summarized and analyzed to help researchers quickly grasp the re-cent progress on seawater oxidation.The outlooks for future research are put forward.The future research directions are proposed as internal and external cultivation,giving full play to the physicochemical prop-erties of electrocatalysts,making sense of structure evolution and OER mechanism,and elucidating the electrical double layer of electrocatalysts.A lot of room for scalable application of seawater electrolysis calls for persistent effort and devotion of related researchers to boost seawater electrolysis development and universal hydrogen energy application.展开更多
AISI 304 stainless steel was ion implanted with Co, and the tribological property on the surface of the stainless steelwas investigated. The Co ion implantation was carried out using a metal vapor vacuum arc (Mevva) b...AISI 304 stainless steel was ion implanted with Co, and the tribological property on the surface of the stainless steelwas investigated. The Co ion implantation was carried out using a metal vapor vacuum arc (Mevva) broad-beam ionsource with an extraction voltage of 40 kV, implantation doses of 3×10^(17)/cm^2 and 5×10^(17)/cm^2, and ion currentdensities of 13, 22 and 32μA/cm^2. The results showed that the near-surface hardness of Co-implanted stainless steelsample was increased by 50% or more, and it increased with increasing ion current density at first and then declined.The friction coefficient decreased from 0.74 to 0.20 after Co implantation. The wear rate after Co implantationreduced by 25% or more as compared to the unimplanted sample. The wear rate initially decreased with increasingion current density and then an increase was observed. Within the range of experimental parameters, there existsa critical ion current density for the Co-implanted stainless steel, at which the wear rate decreased with increasingretained dose, going through a minimum and then increased. The critical ion current density in this paper is about22μA/cm^2.展开更多
Water/seawater oxidation determines the hydrogen production efficiency of water/seawater splitting.De-veloping high-efficiency,conductive,stable,and erosion-resisting transition metal-based layered double hydroxide(TM...Water/seawater oxidation determines the hydrogen production efficiency of water/seawater splitting.De-veloping high-efficiency,conductive,stable,and erosion-resisting transition metal-based layered double hydroxide(TM-LDH)is crucial to water/seawater oxidation.Hence,amorphous high-entropy FeCoNiCr-LDH is fabricated by one-step electrodeposition to promote water/seawater oxidation.Coupling of high entropy,Cr cation leaching,congenetic CrO_(4)^(2-)adsorption,and amorphization to facilitate electrochem-ical reconstruction.The advanced strategy enhances active sites,reaction kinetics,reaction selectivity,conductivity,stability,and corrosion resistance with the electrostatic chlorine-repellent layer.The in-situ Cr leaching and congenetic CrO_(4)^(2-)adsorption-induced electrochemical reconstruction are identified by cyclic voltammetry(CV)activation,in-situ Bode plots,and electrochemical impedance spectroscopy(EIS)plots,ex-situ Raman and ultraviolet-visible spectrophotometry(UV-Vis).The OER active species of oxy-hydroxides are also formed during electrochemical reconstruction.Moreover,control tests of soaking and extra CrO_(4)^(2-)additive verify the superiorities of electrochemical reconstruction with in-situ Cr leaching and congenetic CrO_(4)^(2-)adsorption.Accordingly,FeCoNiCr-LDH exhibits excellent electrochemical perfor-mances with low overpotentials of 193/225 mV at 10 mA cm^(-2),high Faradaic efficiencies of 99.3%/97.4%and strong stability for alkaline water/simulated seawater oxidation,respectively.This study provides one innovative strategy to construct efficient water/seawater oxidation electrocatalysts,showing the great the-oretical significance and practical values in industrial water/seawater splitting for hydrogen production.展开更多
Tissue engineering scaffolds have presented effective value in bone repair.However,the integration of the diverse components,complex structures,multifunction to impart the scaffolds with improved applicability is stil...Tissue engineering scaffolds have presented effective value in bone repair.However,the integration of the diverse components,complex structures,multifunction to impart the scaffolds with improved applicability is still a challenge.Here,we propose a novel fish-derived scaffold combined with photothermal therapy and mesenchymal stem cells(MSCs)to promote bone regeneration.The fish-derived scaffold is composed of the decellularized fish scale and gelatin methacrylate synthesized from fish gelatin(fGelMA),which can promote the proliferation and osteogenesis of MSCs with no obvious immunological rejection.Furthermore,the black phosphorus(BP)nanosheets are incorporated into the fGelMA hydrogel network,which can endow the hydrogel with the capacity of photothermal conversion stimulated by near-infrared(NIR)light.The fish-derived scaffold can promote the osteogenesis process of MSCs with higher expression of osteogenic markers and higher mineralization assisted by the NIR light in vitro.The regeneration of mice calvarial defect has also been accelerated by the scaffold with photothermal therapy and MSCs.These results suggest that the fish-derived scaffold,photothermal therapy,MSCs-based regenerative therapy is a promising clinical strategy in bone regeneration.展开更多
Most of the behavior models with respect to Web applications focus on sequencing of events,without regard for the changes of parameters or elements and the relationship between trigger conditions of events and Web pag...Most of the behavior models with respect to Web applications focus on sequencing of events,without regard for the changes of parameters or elements and the relationship between trigger conditions of events and Web pages.As a result,these models are not sufficient to effectively represent the dynamic behavior of the Web2.0 application.Therefore,in this paper,to appropriately describe the dynamic behavior of the client side of Web applications,we define a novel Client-side Behavior Model(CBM)for Web applications and present a user behavior trace-based modeling method to automatically generate and optimize CBMs.To verify the effectiveness of our method,we conduct a series of experiments on six Web applications according to three types of user behavior traces.The experimental results show that our modeling method can construct CBMs automatically and effectively,and the CBMs built are more precise to represent the dynamic behavior of Web applications.展开更多
基金the Natural Science Foundation of Jiangsu Province (Grant No. BK20171200) for their financial support
文摘Developing an e cient and durable oxygen reduction electrocatalyst is critical for clean-energy technology, such as fuel cells and metal–air batteries. In this study, we developed a facile strategy for the preparation of flexible, porous, and well-dispersed metal–heteroatom-doped carbon nanofibers by direct carbonization of electrospun Zn/Co-ZIFs/PAN nanofibers(Zn/Co-ZIFs/PAN). The obtained Zn/Co and N co-doped porous carbon nanofibers carbonized at 800 °C(Zn/Co–N@PCNFs-800) presented a good flexibility, a continuous porous structure, and a superior oxygen reduction reaction(ORR) catalytic activity to that of commercial 20 wt% Pt/C, in terms of its onset potential(0.98 V vs. RHE), half-wave potential(0.89 V vs. RHE), and limiting current density(-5.26 mA cm^(-2)). In addition, we tested the suitability and durability of Zn/Co–N@PCNFs-800 as the oxygen cathode for a rechargeable Zn–air battery. The prepared Zn–air batteries exhibited a higher power density(83.5 mW cm^(-2)), a higher specific capacity(640.3 mAh g^(-1)), an excellent reversibility, and a better cycling life than the commercial 20 wt% Pt/C + RuO_2 catalysts. This design strategy of flexible porous non-precious metal-doped ORR electrocatalysts obtained from electrospun ZIFs/polymer nanofibers could be extended to fabricate other novel, stable, and easy-to-use multi-functional electrocatalysts for clean-energy technology.
基金supported by the Natural Science Foundation of Hebei Province(No.B2021208030)the College Students Innovation Training Program(Nos.202206224 and S2021113409001).
文摘Designing and synthesizing cost-effective bifunctional catalysts for overall alkaline water/seawater splitting is still a huge challenge for hydrogen production.Herein,Co/Ni/Fe/Mn based-amorphous high-entropy phosphoxide self-standing electrode(CNFMPO)is synthesized by the facile and fast electrodeposition method.CNFMPO exhibits excellent bifunctional electrocatalytic performances on alkaline water/seawater electrolysis.The hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)overpotentials of CNFMPO in alkaline water/seawater are as low as 43/73 and 252/282 mV to reach a current density of 10 mA cm^(-2),respectively.Additionally,two-electrode electrolyzers with CNFMPO||CNFMPO successfully achieve the current density of 10 mA cm^(-2) at low voltages of 1.54 and 1.56 V for overall alkaline water/seawater splitting,respectively.CNFMPO exhibits satisfactory long-term stability on overall alkaline water/seawater splitting for the surface reconstruction into active metal hydroxide/(oxy)hydroxide,phosphite,and phosphate.Moreover,no hypochlorite is detected during seawater electrolysis for the beneficial chlorite oxidation inhibition of the reconstructed phosphite and phosphate.The excellent catalytic performances of CNFMPO are due to the unique amorphous structure,multi-component synergistic effect,beneficial electronic structure modulation,and surface reconstruction during the catalytic reaction process.Therefore,CNFMPO has shown potential promotion to the development of the water/seawater splitting industry as a promising substituent for noble-metal electrocatalysts.This work provides new insights into the design of efficient bifunctional catalysts for overall water/seawater splitting.
基金Financial support by the Natural Science Foundation of Hebei Province(No.B2021208030)the College Students Innovation Training Program(Nos.202206224 and S2021113409001)the Improve the Innovation Capability of Heibei Province(No.225A4404D).
文摘Seawater electrolysis is one most promising development directions for future hydrogen energy.How-ever,big challenges of active site poisoning,chloride oxidation(ClOR),and chloride corrosion on anode electrocatalysts,seriously impede seawater electrolysis development.Therefore,developing efficient an-odic oxygen evolution reaction(OER)electrocatalysts is an urgent task for seawater electrolysis.The ad-vanced strategies of improving OER kinetics,lowering ClOR kinetics,strengthening corrosion resistance,and recombining multifunction are summarized and analyzed to help researchers quickly grasp the re-cent progress on seawater oxidation.The outlooks for future research are put forward.The future research directions are proposed as internal and external cultivation,giving full play to the physicochemical prop-erties of electrocatalysts,making sense of structure evolution and OER mechanism,and elucidating the electrical double layer of electrocatalysts.A lot of room for scalable application of seawater electrolysis calls for persistent effort and devotion of related researchers to boost seawater electrolysis development and universal hydrogen energy application.
文摘AISI 304 stainless steel was ion implanted with Co, and the tribological property on the surface of the stainless steelwas investigated. The Co ion implantation was carried out using a metal vapor vacuum arc (Mevva) broad-beam ionsource with an extraction voltage of 40 kV, implantation doses of 3×10^(17)/cm^2 and 5×10^(17)/cm^2, and ion currentdensities of 13, 22 and 32μA/cm^2. The results showed that the near-surface hardness of Co-implanted stainless steelsample was increased by 50% or more, and it increased with increasing ion current density at first and then declined.The friction coefficient decreased from 0.74 to 0.20 after Co implantation. The wear rate after Co implantationreduced by 25% or more as compared to the unimplanted sample. The wear rate initially decreased with increasingion current density and then an increase was observed. Within the range of experimental parameters, there existsa critical ion current density for the Co-implanted stainless steel, at which the wear rate decreased with increasingretained dose, going through a minimum and then increased. The critical ion current density in this paper is about22μA/cm^2.
基金financially supported by the Natural Science Foundation of Hebei Province(No.B2024208055)the Science Re-search Project of Hebei Education Department(No.QN2022180)the Hebei University of Science and Technology Funding for basic scientific research operations(No.2024XLM022).
文摘Water/seawater oxidation determines the hydrogen production efficiency of water/seawater splitting.De-veloping high-efficiency,conductive,stable,and erosion-resisting transition metal-based layered double hydroxide(TM-LDH)is crucial to water/seawater oxidation.Hence,amorphous high-entropy FeCoNiCr-LDH is fabricated by one-step electrodeposition to promote water/seawater oxidation.Coupling of high entropy,Cr cation leaching,congenetic CrO_(4)^(2-)adsorption,and amorphization to facilitate electrochem-ical reconstruction.The advanced strategy enhances active sites,reaction kinetics,reaction selectivity,conductivity,stability,and corrosion resistance with the electrostatic chlorine-repellent layer.The in-situ Cr leaching and congenetic CrO_(4)^(2-)adsorption-induced electrochemical reconstruction are identified by cyclic voltammetry(CV)activation,in-situ Bode plots,and electrochemical impedance spectroscopy(EIS)plots,ex-situ Raman and ultraviolet-visible spectrophotometry(UV-Vis).The OER active species of oxy-hydroxides are also formed during electrochemical reconstruction.Moreover,control tests of soaking and extra CrO_(4)^(2-)additive verify the superiorities of electrochemical reconstruction with in-situ Cr leaching and congenetic CrO_(4)^(2-)adsorption.Accordingly,FeCoNiCr-LDH exhibits excellent electrochemical perfor-mances with low overpotentials of 193/225 mV at 10 mA cm^(-2),high Faradaic efficiencies of 99.3%/97.4%and strong stability for alkaline water/simulated seawater oxidation,respectively.This study provides one innovative strategy to construct efficient water/seawater oxidation electrocatalysts,showing the great the-oretical significance and practical values in industrial water/seawater splitting for hydrogen production.
基金the National Key Research and Development Project(No.2021YFA1201404)Key Program of National Natural Science Foundation of China(No.81730067)+4 种基金Major Project of National Natural Science Foundation of China(No.81991514)the National Natural Science Foundation of China(No.82101184)Shenzhen Fundamental Research Program(No.JCYJ20210324102809024)Shenzhen PhD Start-up Program(No.RCBS20210609103713045)Jiangsu Provincial Key Medical Center Foundation,Jiangsu Provincial Medical Outstanding Talent Foundation,Jiangsu Provincial Medical Youth Talent Foundation,Jiangsu Provincial Key Medical Talent Foundation,and the Fundamental Research Funds for the Central Universities(Nos.14380493 and 14380494).
文摘Tissue engineering scaffolds have presented effective value in bone repair.However,the integration of the diverse components,complex structures,multifunction to impart the scaffolds with improved applicability is still a challenge.Here,we propose a novel fish-derived scaffold combined with photothermal therapy and mesenchymal stem cells(MSCs)to promote bone regeneration.The fish-derived scaffold is composed of the decellularized fish scale and gelatin methacrylate synthesized from fish gelatin(fGelMA),which can promote the proliferation and osteogenesis of MSCs with no obvious immunological rejection.Furthermore,the black phosphorus(BP)nanosheets are incorporated into the fGelMA hydrogel network,which can endow the hydrogel with the capacity of photothermal conversion stimulated by near-infrared(NIR)light.The fish-derived scaffold can promote the osteogenesis process of MSCs with higher expression of osteogenic markers and higher mineralization assisted by the NIR light in vitro.The regeneration of mice calvarial defect has also been accelerated by the scaffold with photothermal therapy and MSCs.These results suggest that the fish-derived scaffold,photothermal therapy,MSCs-based regenerative therapy is a promising clinical strategy in bone regeneration.
基金supported by the National Natural Science Foundation of China(Nos.61672085,61702029,and 61872026)。
文摘Most of the behavior models with respect to Web applications focus on sequencing of events,without regard for the changes of parameters or elements and the relationship between trigger conditions of events and Web pages.As a result,these models are not sufficient to effectively represent the dynamic behavior of the Web2.0 application.Therefore,in this paper,to appropriately describe the dynamic behavior of the client side of Web applications,we define a novel Client-side Behavior Model(CBM)for Web applications and present a user behavior trace-based modeling method to automatically generate and optimize CBMs.To verify the effectiveness of our method,we conduct a series of experiments on six Web applications according to three types of user behavior traces.The experimental results show that our modeling method can construct CBMs automatically and effectively,and the CBMs built are more precise to represent the dynamic behavior of Web applications.
