The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions.Regulating the elec-trical double layer via the electrode/electro...The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions.Regulating the elec-trical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes.Herein,we report an ultrathin zincophilic ZnS layer as a model regu-lator.At a given cycling current,the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer(stern layer)and a suppressed diffuse layer,indicating the regulated charge distribution and decreased electric double layer repulsion force.Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance.Consequently,the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm^(-2) with a lower overpotential of 25 mV.When coupled with an I2/AC cathode,the cell demonstrates a high rate performance of 160 mAh g^(-1) at 0.1 A g^(-1) and long cycling stability of over 10,000 cycles at 10 A g^(-1).The Zn||MnO_(2) also sustains both high capacity and long cycling stability of 130 mAh g^(-1) after 1,200 cycles at 0.5 A g^(-1).展开更多
Catalytic properties of MnOx-FeOx complex oxide (hereafter denoted as Mn-Fe) catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, su...Catalytic properties of MnOx-FeOx complex oxide (hereafter denoted as Mn-Fe) catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, such as N2 physisorption, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature-programmed reduction (TPR) and their catalytic activities were evaluated with the selective catalytic reduction (SCR) of NOx by NH3. It was found that with the addition of Cr, more NO could be removed in the low-temperature window (below 120 ℃). Among the tested catalysts, Mn-Fe- Cr (2 : 2 : 1) catalyst exhibited the best catalytic performance at 80 ℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that (1) the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; (2) Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate (-NH3+), which favored the low-temperature SCR reaction.展开更多
Direct recycling has been regarded as one of the most promising approaches to dealing with the increasing amount of spent lithium‐ion batteries(LIBs).However,the current direct recycling method remains insufficient t...Direct recycling has been regarded as one of the most promising approaches to dealing with the increasing amount of spent lithium‐ion batteries(LIBs).However,the current direct recycling method remains insufficient to regenerate outdated cathodes to meet current industry needs as it only aims at recovering the structure and composition of degraded cathodes.Herein,a nickel(Ni)and manganese(Mn)co‐doping strategy has been adopted to enhance LiCoO_(2)(LCO)cathode for next‐generation high‐performance LIBs through a conventional hydrothermal treatment combined with short annealing approach.Unlike direct recycling methods that make no changes to the chemical composition of cathodes,the unique upcycling process fabricates a series of cathodes doped with different contents of Ni and Mn.The regenerated LCO cathode with 5%doping delivers excellent electrochemical performance with a discharge capacity of 160.23 mAh g^(−1) at 1.0 C and capacity retention of 91.2%after 100 cycles,considerably surpassing those of the pristine one(124.05 mAh g^(−1) and 89.05%).All results indicate the feasibility of such Ni–Mn co‐doping‐enabled upcycling on regenerating LCO cathodes.展开更多
Nb2O5-carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source, and stuclled as an anode material for high-performance lithium ion battery. The structural c...Nb2O5-carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source, and stuclled as an anode material for high-performance lithium ion battery. The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb2O5 nanocrystals. Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb2O5 from volume change and pulverization during the charge-discharge process. In addition, the carbon shell efficiently improves the rate capability. Even at a current density of 500 mA.g-1, the composite electrode still exhibits a specific capacity of ~100 mAh.g-1. These results suggest the possibility to utilize the Nb2O5-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.展开更多
The coronavirus disease 2019(COVID-19)pandemic is challenging the current public health emergency response systems(PHERSs)of many countries.Although environmental factors,such as those influencing the survival of viru...The coronavirus disease 2019(COVID-19)pandemic is challenging the current public health emergency response systems(PHERSs)of many countries.Although environmental factors,such as those influencing the survival of viruses and their transmission between species including humans,play important roles in PHERSs,little attention has been given to these factors.This study describes and elucidates the roles of environmental factors in future PHERSs.To improve countries’capability to respond to public health emergencies associated with viral infections such as the COVID-19 pandemic,a number of environmental factors should be considered before,during,and after the responses to such emergencies.More specifically,to prevent pandemic outbreaks,we should strengthen environmental and wildlife protection,conduct detailed viral surveillance in animals and hotspots,and improve early-warning systems.During the pandemic,we must study the impacts of environmental factors on viral behaviors,develop control measures to minimize secondary environmental risks,and conduct timely assessments of viral risks and secondary environmental effects with a view to reducing the impacts of the pandemic on human health and on ecosystems.After the pandemic,we should further strengthen surveillance for viruses and the prevention of viral spread,maintain control measures for minimizing secondary environmental risks,develop our capability to scientifically predict pandemics and resurgences,and prepare for the next unexpected resurgence.Meanwhile,we should restore the normal life and production of the public based on the“One Health”concept,that views global human and environmental health as inextricably linked.Our recommendations are essential for improving nations’capability to respond to global public health emergencies.展开更多
The low-temperature physical vapor deposition process of atomically thin two-dimensional transition metal dichalcogenide(2D TMD) has been gaining attention owing to the cost-effective production of diverse electrochem...The low-temperature physical vapor deposition process of atomically thin two-dimensional transition metal dichalcogenide(2D TMD) has been gaining attention owing to the cost-effective production of diverse electrochemical catalysts for hydrogen evolution reaction(HER) applications. We, herein, propose a simple route toward the cost-effective physical vapor deposition process of 2D WSe2 layered nanofilms as HER electrochemical catalysts using RF magnetron sputtering at room temperature(<27℃). By controlling the variable sputtering parameters, such as RF power and deposition time, the loading amount and electrochemical surface area(ECSA) of WSe2 films deposited on carbon paper can be carefully determined. The surface of the sputtered WSe2 films are partially oxidized, which may cause spherical-shaped particles. Regardless of the loading amount of WSe2, Tafel slopes of WSe2 electrodes in the HER test are narrowly distributed to be ~120–138 mV dec-1, which indicates the excellent reproducibility of intrinsic catalytic activity. By considering the trade-off between the loading amount and ECSA, the best HER performance is clearly observed in the 200 W-15 min sample with an overpotential of 220 mV at a current density of 10 mA cm-2. Such a simple sputtering method at low temperature can be easily expanded to other 2D TMD electrochemical catalysts, promising potentially practical electrocatalysts.展开更多
Network functions virtualization(NFV) increases network flexibility and scalability by virtualizing network functions running on the general servers and opens the network innovations by outsourcing VNF instances in 5G...Network functions virtualization(NFV) increases network flexibility and scalability by virtualizing network functions running on the general servers and opens the network innovations by outsourcing VNF instances in 5G networks.However,it leads to the incompatibility issue among different VNF instances,which makes operators difficult to determine which VNF instances to select for Service Function Chains(SFCs).In this paper,we divide VNF instances with high compatibility into clusters used for combining VNF instances in 5G networks.Firstly,we define compatibility among different VNF instances.Secondly,aiming to maximize compatibility of each cluster,we propose a novel hypergraph clustering model that divides the VNF instances into multiple clusters.Then,the hypergraph clustering model is transformed to an evolutionary game.Thus,the cluster establishing is transformed to the game equilibrium searching.Furthermore,we propose a discrete time high order replicator dynamic algorithm to find the game equilibrium.Finally,the simulation results show that the proposed approach can improve the quality of SFCs.展开更多
Production of chemicals and fuels from microcrystalline cellulose has inspired scholars’ attention. Deactivation of metallic catalysts including acid leaching and hydrothermal aggregation is still one of the core iss...Production of chemicals and fuels from microcrystalline cellulose has inspired scholars’ attention. Deactivation of metallic catalysts including acid leaching and hydrothermal aggregation is still one of the core issues in these systems. To address these problems, we designed and fabricated a series of Ni-W/SiO2 catalysts, which were decorated by CxNy species using C-and N- sources and applied in cellulose conversion to C2,3 oxygenated compounds. The Ni-W/SiO2@CxNy catalysts, underwent complexing and selfassembling process, exhibited special heterojunctions, accompanying strong interactions mainly among Ni phase and CxNy layers. Catalytic results showed that the heterojunctions and outer CxNy layers extensively enhanced productions of hydroxyacetone(HDA) and ethylene glycol(EG) and promoted the hydrothermal stability through prospering in concentration of Lewis pairs from Ni–N—N structure and immobilizing the metallic nanoclusters. 48.25% of EG was yielded under 5.0 MPa H2 pressurized 240 ℃ water for 2.0 h. The Lewis pair further improved the formation of HDA with 20.92% yield. High hydrothermal stability of NiW/SiO2@CxNy catalyst was proved according to the recycling results and trace leaching concentration of Ni and W. This construction of metallic catalysts exploited a new strategy to manufacture extraordinary durability of metallic nanoclusters for cellulose conversion under harsh reaction conditions.展开更多
Highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)are imperative for the commercialization application of proton exchange membrane fuel cells.By manipulating ligand effect,structural con...Highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)are imperative for the commercialization application of proton exchange membrane fuel cells.By manipulating ligand effect,structural control,and strain effect,we report here the precise preparation of Mo-doped Pt_(3)Co alloy nanowires(Pt_(3)Co-Mo NWs)as the efficient catalyst towards ORR with high specific activity(0.596 mA cm^(−2))and mass activity(MA,0.84 A mg^(−1)_(Pt)),much higher than those of undoped counterparts.Besides activity,Pt_(3)Co-Mo NWs also demonstrate excellent structural stability and cyclic durability even after 50,000 cycles,again surpassing control samples without Mo dopants.According to the strain maps and DFT calculations,Mo dopants could modify the electronic structure of both Pt and Co to achieve not only optimized oxygen-intermediate binding energy on the interface but also increased the vacancy formation energy of Co,together leading to enhanced activity and durability.This work provides not only a facile methodology but also an in-depth investigation of the relationship between structure and properties to provide general guidance for future design and optimization.展开更多
Micro-supercapacitors(MSCs)are considered as highly competitive power sources for miniaturized electronics.However,narrow voltage window and poor anti-freezing properties of MSCs in conventional aqueous electrolytes l...Micro-supercapacitors(MSCs)are considered as highly competitive power sources for miniaturized electronics.However,narrow voltage window and poor anti-freezing properties of MSCs in conventional aqueous electrolytes lead to low energy density and limited environmental adaption.Herein,we report the construction of low-temperature and high-energy-density MSCs based on anti-freezing hybrid gel electrolytes(HGE)through introducing ethylene glycol(EG)additives into aqueous LiCl electrolyte.Since EG partially destroys hydrogen bond network among water molecules,the HGE exhibits maximum electrochemical stability window of 2.7 V and superior anti-freezing features with a glass transition temperature of-62.8℃.Further,the optimized MSCs using activated carbon microelectrodes possess impressive volumetric capacitance of 28.9 F cm^(-3)and energy density of 10.3 mWh cm^(-3)in the voltage of 1.6 V,2.6 times higher than MSCs tested in 1.2 V.Importantly,the MSCs display 68.3%capacitance retention even at-30℃ compared to the value at 25℃,and ultra-long cyclability with 85.7%of initial capacitance after 15,000 times,indicating extraordinary low-temperature performance.Besides,our devices offer favorable flexibility and modular integration.Therefore,this work provides a general strategy of realizing flexible,safe and anti-freezing microscale power sources,holding great potential towards subzero-temperature microelectronic applications.展开更多
A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with g...A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with graphitic carbon nitride(g-C_3N_4). The AgNPs reduced the fluorescence intensity of g-C_3N_4. Acetylthiocholine(ATCh) could be catalytically hydrolyzed by acetylcholinesterase(AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C_3N_4, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 mg/L(S/N=3). In addition, the absorption of the g-C_3N_4/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.展开更多
Flexibility and multifunctionality are now becoming inevitable worldwide tendencies for electronic devices to meet modern life's convenience,efficiency,and quality demand.To that end,developing flexible and wearab...Flexibility and multifunctionality are now becoming inevitable worldwide tendencies for electronic devices to meet modern life's convenience,efficiency,and quality demand.To that end,developing flexible and wearable energy storage devices is a must.Recently,aqueous zinc-ion batteries(ZIBs)and zinc-ion capacitors(ZICs)stand out as two of the most potent candidates for wearable electronics due to their excellent electrochemical performance,intrinsic safety,low cost,and functional controllability.Simultaneously,polymer electrolytes'introduction and rational design,especially various hydrogels,have endowed conventional ZIBs and ZICs with colorful functions,which has been regarded as a perfect answer for energy suppliers integrated into those advanced wearable electronic devices.This review focuses on the functional hydrogel electrolytes(HEs)and their application for ZIBs and ZICs.Previously reported HEs for ZIBs and ZICs were classified and analyzed,from the flexibility to mechanical endurance,temperature adaptability,electrochemical stability,and finally cell-level ZIBs and ZICs based on multifunctional HEs.Besides introducing the diverse and exciting functions of HEs,working principles were also analyzed.Ultimately,all the details of these examples were summarized,and the related challenges,constructive solutions,and futural prospects of functional ZIBs and ZICs were also dedicatedly evaluated.展开更多
Lean electrolyte usage in lithium–sulfur battery(LSB)meets the demand of the high energy density.However,lean condition makes the electrolyte-related interface discrete,leading to retardation of ion transfer that dep...Lean electrolyte usage in lithium–sulfur battery(LSB)meets the demand of the high energy density.However,lean condition makes the electrolyte-related interface discrete,leading to retardation of ion transfer that depends on interfaces.Consequently,electrochemical reactions face restraint.Herein,lithium polyacrylate acid(LiPAA)with short-chain anions(molecular weight of 2000)is introduced into the cathode.Because of the polysulfide(PS)-philic instinct of the short-chain PAA anions,short-chain PS is captured inside of the cathode.In addition,LiPAA supplies Li^(+)to the short-chain PS captured.The strong interaction between Li_(2)S_(4)and LiPAA effectively decreases Li_(2)S_(4)migration to the anode during discharging.In a sense,the ion mass transfer pattern is thus changed comparing to traditional long-way mode between cathode and anode.Galvanostatic intermittent titration technique(GITT)proves that the interfacial reaction resistance is greatly decreased in the region where Li_(2)S_(x)(x≤4)reduction contributes most.In the same time,the reversibility of electrochemical reduction/oxidation is improved.Owing to the accelerated Li_(2)S_(x)(x≤4)reduction,Li implanting of only 0.3 wt.%plus O introduction up to 1.4 wt.%enables the LSB perform well even with 1/4 of regular electrolyte dosage(5μL mg^(-1))and high-sulfur loading(4.2 mg cm^(-2)),increasing its rate capacity C_(0.8/0.5)from 52.6%(without the LiPAA)to 92.3%(with the LiP AA)as well as a capacity of 518.7 mAh g^(-1)after 400 cycles at 0.8 mA cm^(-2).展开更多
基金financially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC),through the Discovery Grant Program (RGPIN-2018-06725)the Discovery Accelerator Supplement Grant program (RGPAS-2018-522651)+2 种基金the New Frontiers in Research Fund-Exploration program (NFRFE-2019-00488)supported by funding from the Canada First Research Excellence Fund as part of the University of Alberta’s Future Energy Systems research initiative (FES-T06-Q03)supported by the Chinese Scholarship Council (CSC)(Grant No. 202006450027).
文摘The practical application of aqueous zinc-ion batteries for large-grid scale systems is still hindered by uncontrolled zinc dendrite and side reactions.Regulating the elec-trical double layer via the electrode/electrolyte interface layer is an effective strategy to improve the stability of Zn anodes.Herein,we report an ultrathin zincophilic ZnS layer as a model regu-lator.At a given cycling current,the cell with Zn@ZnS electrode displays a lower potential drop over the Helmholtz layer(stern layer)and a suppressed diffuse layer,indicating the regulated charge distribution and decreased electric double layer repulsion force.Boosted zinc adsorption sites are also expected as proved by the enhanced electric double-layer capacitance.Consequently,the symmetric cell with the ZnS protection layer can stably cycle for around 3,000 h at 1 mA cm^(-2) with a lower overpotential of 25 mV.When coupled with an I2/AC cathode,the cell demonstrates a high rate performance of 160 mAh g^(-1) at 0.1 A g^(-1) and long cycling stability of over 10,000 cycles at 10 A g^(-1).The Zn||MnO_(2) also sustains both high capacity and long cycling stability of 130 mAh g^(-1) after 1,200 cycles at 0.5 A g^(-1).
基金supported by Jiangsu Natural Science Foundation (No. BK2012347)the National High Technology and Development Program of China (863 Programs, No.2007AA061802)
文摘Catalytic properties of MnOx-FeOx complex oxide (hereafter denoted as Mn-Fe) catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, such as N2 physisorption, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature-programmed reduction (TPR) and their catalytic activities were evaluated with the selective catalytic reduction (SCR) of NOx by NH3. It was found that with the addition of Cr, more NO could be removed in the low-temperature window (below 120 ℃). Among the tested catalysts, Mn-Fe- Cr (2 : 2 : 1) catalyst exhibited the best catalytic performance at 80 ℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that (1) the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; (2) Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate (-NH3+), which favored the low-temperature SCR reaction.
基金support of NanoFAB in Electron Microscopy and FIB sample preparation at the University of Alberta in Canadasupported by the Natural Sciences and Engineering Research Council of Canada(NSERC)+3 种基金through the Discovery Grant Program(RGPIN-2018-06725)the Discovery Accelerator Supplement Grant program(RGPAS-2018-522651)by the New Frontiers in Research Fund-Exploration program(NFRFE-2019-00488)financial support from the University of Alberta and Future Energy Systems(FES-T06-Q03).
文摘Direct recycling has been regarded as one of the most promising approaches to dealing with the increasing amount of spent lithium‐ion batteries(LIBs).However,the current direct recycling method remains insufficient to regenerate outdated cathodes to meet current industry needs as it only aims at recovering the structure and composition of degraded cathodes.Herein,a nickel(Ni)and manganese(Mn)co‐doping strategy has been adopted to enhance LiCoO_(2)(LCO)cathode for next‐generation high‐performance LIBs through a conventional hydrothermal treatment combined with short annealing approach.Unlike direct recycling methods that make no changes to the chemical composition of cathodes,the unique upcycling process fabricates a series of cathodes doped with different contents of Ni and Mn.The regenerated LCO cathode with 5%doping delivers excellent electrochemical performance with a discharge capacity of 160.23 mAh g^(−1) at 1.0 C and capacity retention of 91.2%after 100 cycles,considerably surpassing those of the pristine one(124.05 mAh g^(−1) and 89.05%).All results indicate the feasibility of such Ni–Mn co‐doping‐enabled upcycling on regenerating LCO cathodes.
基金supported by Nano Special Plan from Shanghai Municipal Science and Technology Plan of Commission(No.l052nm06900)
文摘Nb2O5-carbon nanocomposite is synthesized through a facile one-step hydrothermal reaction from sucrose as the carbon source, and stuclled as an anode material for high-performance lithium ion battery. The structural characterizations reveal that the nanocomposite possesses a core-shell structure with a thin layer of carbon shell homogeneously coated on the Nb2O5 nanocrystals. Such a unique structure enables the composite electrode with a long cycle life by preventing the Nb2O5 from volume change and pulverization during the charge-discharge process. In addition, the carbon shell efficiently improves the rate capability. Even at a current density of 500 mA.g-1, the composite electrode still exhibits a specific capacity of ~100 mAh.g-1. These results suggest the possibility to utilize the Nb2O5-carbon core-shell composite as a high performance anode material in the practical application of lithium ion battery.
基金the National Science Foundation of China(41925031,41991315,and 41521003).
文摘The coronavirus disease 2019(COVID-19)pandemic is challenging the current public health emergency response systems(PHERSs)of many countries.Although environmental factors,such as those influencing the survival of viruses and their transmission between species including humans,play important roles in PHERSs,little attention has been given to these factors.This study describes and elucidates the roles of environmental factors in future PHERSs.To improve countries’capability to respond to public health emergencies associated with viral infections such as the COVID-19 pandemic,a number of environmental factors should be considered before,during,and after the responses to such emergencies.More specifically,to prevent pandemic outbreaks,we should strengthen environmental and wildlife protection,conduct detailed viral surveillance in animals and hotspots,and improve early-warning systems.During the pandemic,we must study the impacts of environmental factors on viral behaviors,develop control measures to minimize secondary environmental risks,and conduct timely assessments of viral risks and secondary environmental effects with a view to reducing the impacts of the pandemic on human health and on ecosystems.After the pandemic,we should further strengthen surveillance for viruses and the prevention of viral spread,maintain control measures for minimizing secondary environmental risks,develop our capability to scientifically predict pandemics and resurgences,and prepare for the next unexpected resurgence.Meanwhile,we should restore the normal life and production of the public based on the“One Health”concept,that views global human and environmental health as inextricably linked.Our recommendations are essential for improving nations’capability to respond to global public health emergencies.
基金supported by the Fundamental Research Program of the Korean Institute of Materials Science(Grant PNK6130)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT,Ministry of Science and ICT)(No.2017R1C1B1005076)+1 种基金financially supported by the Ministry of Trade,Industry and Energy(MOTIE)Korea Institute for Advancement of Technology(KIAT)through the National Innovation Cluster R&D program(P0006704_Development of energy saving advanced parts)。
文摘The low-temperature physical vapor deposition process of atomically thin two-dimensional transition metal dichalcogenide(2D TMD) has been gaining attention owing to the cost-effective production of diverse electrochemical catalysts for hydrogen evolution reaction(HER) applications. We, herein, propose a simple route toward the cost-effective physical vapor deposition process of 2D WSe2 layered nanofilms as HER electrochemical catalysts using RF magnetron sputtering at room temperature(<27℃). By controlling the variable sputtering parameters, such as RF power and deposition time, the loading amount and electrochemical surface area(ECSA) of WSe2 films deposited on carbon paper can be carefully determined. The surface of the sputtered WSe2 films are partially oxidized, which may cause spherical-shaped particles. Regardless of the loading amount of WSe2, Tafel slopes of WSe2 electrodes in the HER test are narrowly distributed to be ~120–138 mV dec-1, which indicates the excellent reproducibility of intrinsic catalytic activity. By considering the trade-off between the loading amount and ECSA, the best HER performance is clearly observed in the 200 W-15 min sample with an overpotential of 220 mV at a current density of 10 mA cm-2. Such a simple sputtering method at low temperature can be easily expanded to other 2D TMD electrochemical catalysts, promising potentially practical electrocatalysts.
基金supported by The National High Technology Research and Development Program of China(863)(Grant No.2014AA01A701,2015AA01A706)
文摘Network functions virtualization(NFV) increases network flexibility and scalability by virtualizing network functions running on the general servers and opens the network innovations by outsourcing VNF instances in 5G networks.However,it leads to the incompatibility issue among different VNF instances,which makes operators difficult to determine which VNF instances to select for Service Function Chains(SFCs).In this paper,we divide VNF instances with high compatibility into clusters used for combining VNF instances in 5G networks.Firstly,we define compatibility among different VNF instances.Secondly,aiming to maximize compatibility of each cluster,we propose a novel hypergraph clustering model that divides the VNF instances into multiple clusters.Then,the hypergraph clustering model is transformed to an evolutionary game.Thus,the cluster establishing is transformed to the game equilibrium searching.Furthermore,we propose a discrete time high order replicator dynamic algorithm to find the game equilibrium.Finally,the simulation results show that the proposed approach can improve the quality of SFCs.
基金financially supported by the Natural Science Foundation of Zhejiang Province of China(No.LY19B060002)the Enterprise Research Programme by Huzhou City of Zhejiang Province(China)founded by Huzhou Municipal Government(20190040)。
文摘Production of chemicals and fuels from microcrystalline cellulose has inspired scholars’ attention. Deactivation of metallic catalysts including acid leaching and hydrothermal aggregation is still one of the core issues in these systems. To address these problems, we designed and fabricated a series of Ni-W/SiO2 catalysts, which were decorated by CxNy species using C-and N- sources and applied in cellulose conversion to C2,3 oxygenated compounds. The Ni-W/SiO2@CxNy catalysts, underwent complexing and selfassembling process, exhibited special heterojunctions, accompanying strong interactions mainly among Ni phase and CxNy layers. Catalytic results showed that the heterojunctions and outer CxNy layers extensively enhanced productions of hydroxyacetone(HDA) and ethylene glycol(EG) and promoted the hydrothermal stability through prospering in concentration of Lewis pairs from Ni–N—N structure and immobilizing the metallic nanoclusters. 48.25% of EG was yielded under 5.0 MPa H2 pressurized 240 ℃ water for 2.0 h. The Lewis pair further improved the formation of HDA with 20.92% yield. High hydrothermal stability of NiW/SiO2@CxNy catalyst was proved according to the recycling results and trace leaching concentration of Ni and W. This construction of metallic catalysts exploited a new strategy to manufacture extraordinary durability of metallic nanoclusters for cellulose conversion under harsh reaction conditions.
基金financially supported by the Natural Sciences and Engineering Research Council of Canada(NSERC),through the Discovery Grant Program(RGPIN-2018-06725RGPIN-201705080)+2 种基金the Discovery Accelerator Supplement Grant program(RGPAS-2018-522651)by the New Frontiers in Research Fund-Exploration program(NFRFE-2019-00488)support from the University of Alberta and Future Energy Systems(FES)。
文摘Highly active and durable electrocatalysts towards oxygen reduction reaction(ORR)are imperative for the commercialization application of proton exchange membrane fuel cells.By manipulating ligand effect,structural control,and strain effect,we report here the precise preparation of Mo-doped Pt_(3)Co alloy nanowires(Pt_(3)Co-Mo NWs)as the efficient catalyst towards ORR with high specific activity(0.596 mA cm^(−2))and mass activity(MA,0.84 A mg^(−1)_(Pt)),much higher than those of undoped counterparts.Besides activity,Pt_(3)Co-Mo NWs also demonstrate excellent structural stability and cyclic durability even after 50,000 cycles,again surpassing control samples without Mo dopants.According to the strain maps and DFT calculations,Mo dopants could modify the electronic structure of both Pt and Co to achieve not only optimized oxygen-intermediate binding energy on the interface but also increased the vacancy formation energy of Co,together leading to enhanced activity and durability.This work provides not only a facile methodology but also an in-depth investigation of the relationship between structure and properties to provide general guidance for future design and optimization.
基金financially supported by the National Natural Science Foundation of China(22125903,51872283,22109160,22005297)the Dalian Innovation Support Plan for High Level Talents(2019RT09)+6 种基金the The Joint Fund of the Yulin University and the Dalian National Laboratory For Clean Energy(DNL),CAS,DNL Cooperation Fund,CAS(DNL201912,DNL201915,DNL202016,DNL202019),DICP(DICP ZZBS201802,DICP I2020032)The Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy(YLU-DNL Fund 2021002,YLU-DNL Fund 2021009)the China Postdoctoral Science Foundation(2021M693126,2020M680995,2021M703145,2021M693127)the International Postdoctoral Exchange Fellowship Program(Talent-Introduction Program)(YJ20210311)the Plan for promoting innovative talents of Education Department of Liaoning Province(LCR2018015)the Shenyang Youth Science and Technology Project(RC200444)the Natural Science Foundation of Liaoning Province(2021-MS-234)。
文摘Micro-supercapacitors(MSCs)are considered as highly competitive power sources for miniaturized electronics.However,narrow voltage window and poor anti-freezing properties of MSCs in conventional aqueous electrolytes lead to low energy density and limited environmental adaption.Herein,we report the construction of low-temperature and high-energy-density MSCs based on anti-freezing hybrid gel electrolytes(HGE)through introducing ethylene glycol(EG)additives into aqueous LiCl electrolyte.Since EG partially destroys hydrogen bond network among water molecules,the HGE exhibits maximum electrochemical stability window of 2.7 V and superior anti-freezing features with a glass transition temperature of-62.8℃.Further,the optimized MSCs using activated carbon microelectrodes possess impressive volumetric capacitance of 28.9 F cm^(-3)and energy density of 10.3 mWh cm^(-3)in the voltage of 1.6 V,2.6 times higher than MSCs tested in 1.2 V.Importantly,the MSCs display 68.3%capacitance retention even at-30℃ compared to the value at 25℃,and ultra-long cyclability with 85.7%of initial capacitance after 15,000 times,indicating extraordinary low-temperature performance.Besides,our devices offer favorable flexibility and modular integration.Therefore,this work provides a general strategy of realizing flexible,safe and anti-freezing microscale power sources,holding great potential towards subzero-temperature microelectronic applications.
基金financially supported by the National Natural Science Foundation of China (Grant No. 21765015, 21808099 to P. Qiu, 31860263 to X. Wang)the Science and Technology Innovation Platform of Jiangxi Province (Grant No. 20192BCD40001), China。
文摘A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with graphitic carbon nitride(g-C_3N_4). The AgNPs reduced the fluorescence intensity of g-C_3N_4. Acetylthiocholine(ATCh) could be catalytically hydrolyzed by acetylcholinesterase(AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C_3N_4, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 mg/L(S/N=3). In addition, the absorption of the g-C_3N_4/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC),through the Discovery Grant Program(RGPIN-2018-06725)the Discovery Accelerator Supplement Grant Program(RGPAS-2018-522651)+1 种基金by the New Frontiers in Research Fund-Exploration Program(NFRFE-2019-00488)support from the Canada First Research Excellence Fund as part of the University of Alberta's Future Energy Systems research initiative(FES-T06-Q03).
文摘Flexibility and multifunctionality are now becoming inevitable worldwide tendencies for electronic devices to meet modern life's convenience,efficiency,and quality demand.To that end,developing flexible and wearable energy storage devices is a must.Recently,aqueous zinc-ion batteries(ZIBs)and zinc-ion capacitors(ZICs)stand out as two of the most potent candidates for wearable electronics due to their excellent electrochemical performance,intrinsic safety,low cost,and functional controllability.Simultaneously,polymer electrolytes'introduction and rational design,especially various hydrogels,have endowed conventional ZIBs and ZICs with colorful functions,which has been regarded as a perfect answer for energy suppliers integrated into those advanced wearable electronic devices.This review focuses on the functional hydrogel electrolytes(HEs)and their application for ZIBs and ZICs.Previously reported HEs for ZIBs and ZICs were classified and analyzed,from the flexibility to mechanical endurance,temperature adaptability,electrochemical stability,and finally cell-level ZIBs and ZICs based on multifunctional HEs.Besides introducing the diverse and exciting functions of HEs,working principles were also analyzed.Ultimately,all the details of these examples were summarized,and the related challenges,constructive solutions,and futural prospects of functional ZIBs and ZICs were also dedicatedly evaluated.
基金supported by National Nature Science Foundation of China(NSFC22078228)。
文摘Lean electrolyte usage in lithium–sulfur battery(LSB)meets the demand of the high energy density.However,lean condition makes the electrolyte-related interface discrete,leading to retardation of ion transfer that depends on interfaces.Consequently,electrochemical reactions face restraint.Herein,lithium polyacrylate acid(LiPAA)with short-chain anions(molecular weight of 2000)is introduced into the cathode.Because of the polysulfide(PS)-philic instinct of the short-chain PAA anions,short-chain PS is captured inside of the cathode.In addition,LiPAA supplies Li^(+)to the short-chain PS captured.The strong interaction between Li_(2)S_(4)and LiPAA effectively decreases Li_(2)S_(4)migration to the anode during discharging.In a sense,the ion mass transfer pattern is thus changed comparing to traditional long-way mode between cathode and anode.Galvanostatic intermittent titration technique(GITT)proves that the interfacial reaction resistance is greatly decreased in the region where Li_(2)S_(x)(x≤4)reduction contributes most.In the same time,the reversibility of electrochemical reduction/oxidation is improved.Owing to the accelerated Li_(2)S_(x)(x≤4)reduction,Li implanting of only 0.3 wt.%plus O introduction up to 1.4 wt.%enables the LSB perform well even with 1/4 of regular electrolyte dosage(5μL mg^(-1))and high-sulfur loading(4.2 mg cm^(-2)),increasing its rate capacity C_(0.8/0.5)from 52.6%(without the LiPAA)to 92.3%(with the LiP AA)as well as a capacity of 518.7 mAh g^(-1)after 400 cycles at 0.8 mA cm^(-2).