Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis.However,the harsh electrochemical environment of seawater,par...Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis.However,the harsh electrochemical environment of seawater,particularly the presence of aggressive Cl^(-),has been proven to be prone to parasitic chloride ion oxidation and corrosion reactions,thus restricting seawater electrolyzer lifetime.Herein,hierarchical structure(Ni,Fe)O(OH)@NiCoS nanorod arrays(NAs)catalysts with heterointerfaces and localized oxygen vacancies were synthesized at nickel foam substrates via the combination of hydrothermal and annealing methods to boost seawater dissociation.The hiera rchical nanostructure of NiCoS NAs enhanced electrode charge transfer rate and active surface area to accelerate oxygen evolution reaction(OER)and generated sulfate gradient layers to repulsive aggressive Cl^(-).The fabricated heterostructure and vacancies of(Ni,Fe)O(OH)tuned catalyst electronic structure into an electrophilic state to enhance the binding affinity of hydroxyl intermediates and facilitate the structural transformation into amorphousγ-NiFeOOH for promoting OER.Furthermore,through operando electrochemistry techniques,we found that theγ-NiFeOOH possessing an unsaturated coordination environment and lattice-oxygen-participated OER mechanism can minimize electrode Cl^(-)corrosion enabled by stabilizing the adsorption of OH*intermediates,making it one of the best OER catalysts in the seawater medium reported to date.Consequently,these catalysts can deliver current densities of 100 and 500 mA cm-2for boosting OER at minimal overpotentials of 245and 316 mV,respectively,and thus prevent chloride ion oxidation simultaneously.Impressively,a highly stable anion exchange membrane(AEM)seawater electrolyzer based on the non-noble metal heterostructure electrodes reached a record low degradation rate under 100μV h-1at constant industrial current densities of 400 and 600 mA cm-2over 300 h,which exhibits a promising future for the nonprecious and stable AEMWE in the direct seawater electrolysis industry.展开更多
The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative proba...The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault,which are adopted from relevant studies such as seismological geology,geodesy,and historical earthquake records.Based on the long-term predictions of large earthquakes throughout the world,this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap,motion strongly locked,sparse small-moderate earthquakes,and apparent Coulomb stress increase.This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland.The present loading rate of each fault is first constrained by geodetic observations;the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.展开更多
The central-southern part of the eastern border of the Sichuan-Yunnan rhombic block provides the research strategy of ‘trade space for time' with an interesting fault system, where the segments have similar focal...The central-southern part of the eastern border of the Sichuan-Yunnan rhombic block provides the research strategy of ‘trade space for time' with an interesting fault system, where the segments have similar focal mechanisms and cover almost continuous spectra of elapse rates. We experiment to study the seismological characteristics of different segments with different elapse rates. We employed the de-clustered earthquake catalog for the calculation of b values for each segment. The analysis revealed that different segments have similar b values,which implies that, although different segments have different periods of earthquake recurrence, the 'natural time' for the whole fault system elapses with a homogeneous pace. We extended the earthquake potential score(EPS)for nowcasting earthquakes to a quasi-EPS(q EPS). It is found that q EPS increases with the increase of elapse rates,albeit for those fault segments whose elapse rates have exceeded 1, q EPS may better reflect the seismic hazard.展开更多
Humidity can affect the attenuation of MEA(membrane electrode assembly), however, the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein, we design a simulating auto...Humidity can affect the attenuation of MEA(membrane electrode assembly), however, the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein, we design a simulating automotive protocol, performed on five single fuel cells under RH(relative humidity) 100%,RH 80%, RH 64%, and RH 40%, RH 10%, respectively, to study the relationship of MEA decays and humidity and suggest optimized humidity range to extend the durability. With the electrochemical impedance spectroscopy, cyclic voltammetry, X-ray fluorescence, X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, the four degradation mechanisms about catalyst layer, including Pt dissolution, Pt coarsening, carbon corrosion and ionomer degradation, are observed. Pt coarsening and carbon corrosion are accelerated by higher water content at high humidity. Ionomer degradation and Pt dissolution are enhanced in low humidity. With the linear sweep voltammetry, ion chromatography,nuclear magnetic resonance, tensile test and scan electron microscope, chemical and mechanical degradation in proton exchange membrane are all observed in these five fuels. Chemical degradation, characterized by membrane thinning and more fluoride loss, occurred markedly in RH 10%. Mechanical degradation, characterized by the non-uniformity thickness and bad mechanical properties, is more pronounced in RH 100%, RH 80%, RH 64%. These two degradations are in a moderate level in RH 40%. The research suggests that the RH range from 64% to 40% is conductive to mitigate the degradation of MEAs operated in automotive applications.展开更多
Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of ...Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of the coating are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Interfacial contact resistance (ICR) between the coated sample and carbon paper is 4.9 m Omega cm(2) under 150 N/cm(2), which is much lower than that of the SS316L substrate. Potentiodynamic and potentiostatic tests are performed in the simulated PEMFC working conditions to investigate the corrosion behaviors of the coated sample. Superior anticorrosion performance is observed for the coated sample, whose corrosion current density is 0.12 mu A/cm(2). Surface morphology results after corrosion tests indicate that the substrate is well protected by the multilayer coating. Performances of the single cell with the multilayer coated SS316L bipolar plate are improved significantly compared with that of the cell with the uncoated SS316L bipolar plate, presenting a great potential for PEMFC application. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Significant postseismic deformation of the 2008 M W 7.9 Wenchuan earthquake has been observed from GPS data of the first 14 days after the earthquake. The possible mechanisms for the rapid postseismic deformation are ...Significant postseismic deformation of the 2008 M W 7.9 Wenchuan earthquake has been observed from GPS data of the first 14 days after the earthquake. The possible mechanisms for the rapid postseismic deformation are assumed to be afterslip on the earthquake rupture plane and viscoelastic relaxation of coseismiclly stress change in the lower crust or upper mantle. We firstly use the constrained least squares method to find an afterslip model which can fit the GPS data best. The afterslip model can explain near-field data very well but shows considerable discrepancies in fitting far-field data. To estimate the effect due to the viscoelastic relaxation in the lower crust, we then ignore the contribution from the afterslip and attempt to invert the viscosity structure beneath the Longmenshan fault where the Wenchuan earthquake occurred from the postseismic deformation data. For this purpose, we use a viscoelastic model with a 2D geometry based on the geological and seismological observations and the coseismic slip distribution derived from the coseismic GPS and InSAR data. By means of a grid search we find that the optimum viscosity is 9×10 18 Pa·s for the middle-lower crust in the Chengdu Basin, 4×10 17 Pa·s for the middle-lower crust in the Chuanxi Plateau and 7×10 17 Pa·s for the low velocity zone in the Chuanxi plateau. The viscoelastic model explains the postseismic deformation observed in the far-field satisfactorily, but it is considerably worse than the afterslip model in fitting the near-fault data. It suggests therefore a hybrid model including both afterslip and relaxation effects. Since the viscoelastic model produces mainly the far-field surface deformation and has fewer degree of freedoms (three viscosity parameters) than the afterslip model with a huge number of source parameters, we fix the viscositiy structure as obtained before but redetermine the afterslip distribution using the residual data from the viscoelastic modeling. The redetermined afterslip distribution becomes physically more reasonable; it is more localized and exhibits a pattern spatially complementary with the coseismic rupture distribution. We conclude that the aseismic fault slip is responsible for the near-fault postseismic deformation, whereas the viscoelastic stress relaxation might be the major cause for the far-field postseismic deformation.展开更多
Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the v...Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the vigorous support of China's national policy, research institutes and enterprises have carried out extensive and pragmatic work on the basic materials, key components, stacks, auxiliary systems of PEMFCs, as well as the hydrogen station construction in order to realize the wide application of hydrogen energy.PEMFC System and Engineering Research Center of DICP is one of the earliest players in the H2-PEMFCs field.Advances have been achieved in the fields of low-platinum contained catalysts,PEMs, high-efficiency MEAs, low-cost metal bipolar plates, low-temperature and impurity air environment adaptability, stacks and systems.This paper introduces recent progresses of H2-PEMFCs at DICP in key materials, components, stacks, systems and the applications.The engineering status of proton exchange membrane water electrolysis(PEMWE) and the alkaline anion exchange membrane fuel cells(AEMFCs)are also summarized.展开更多
To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black thr...To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black through a strategy involving modified glycol reduction and chemical etching.The obtained Pt36Co/C catalyst exhibits a much larger electrochemical surface area(ECSA)and an improved ORR electrocatalytic activity compared to commercial Pt/C.Moreover,an electrode prepared with Pt36Co/C was further evaluated under H2-air single cell test conditions,and exhibited a maximum specific power density of 10.27 W mgPt^-1,which is 1.61 times higher than that of a conventional Pt/C electrode and also competitive with most state-of-the-art Pt-based architectures.In addition,the changes in ECSA,power density,and reacting resistance during the accelerated degradation process further demonstrate the enhanced durability of the Pt36Co/C electrode.The superior performance observed in this work can be attributed to the synergy between the ultrasmall size and homogeneous distribution of catalyst nanoparticles,bimetallic ligand and electronic effects,and the dissolution of unstable Co with the rearrangement of surface structure brought about by acid etching.Furthermore,the accessible raw materials and simplified operating procedures involved in the fabrication process would result in great cost-effectiveness for practical applications of PEMFCs.展开更多
The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this stu...The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this study, membrane electrode assemblies with different Pt-loadings were prepared, and PEMFCs were assembled using those membrane electrode assemblies with traditional solid plate and water transport plate as cathode flow-field plates, respectively. The performance and electrochemical surface area of cells were characterized to evaluate the membrane electrode assemblies degradation after rapid currentvariation cycles. Scanning electron microscope and transmission electron microscope were used to investigate the decay of catalyst layers and Pt/C catalyst. With the increase of Pt-loading, the performance degradation of membrane electrode assemblies will be mitigated. But higher Pt-loading means thicker catalyst layer, which leads to a longer pathway of mass transfer, and it may result in carbon material corrosion in membrane electrode assemblies. The decay of Pt/C catalyst in cathode is mainly caused by the corrosion of carbon support, and the degradation of anode Pt/C catalyst is a consequence of migration and aggregation of Pt particles. And using water transport plate is beneficial to alleviating the age of cathode Pt/C catalyst.展开更多
Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Electrochemical results and single cell tests show that an en...Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Electrochemical results and single cell tests show that an enhanced activity for the oxygen reduction reaction (ORR) is obtained for the Pt/WO3/C catalyst compared with Pt/C. The higher catalytic activity might be ascribed to the improved Pt dispersion with smaller particle sizes. The Pt/WO3/C catalyst also exhibits a good electrochemical stability under potential cycling. Thus, the Pt/WO3/C catalyst can be used as a potential PEMFC cathode catalyst.展开更多
It is a great challenge to develop membrane materials with high performance and long durability for acidalkaline amphoteric water electrolysis.Hence,the graphitic carbon nitride(g-C_(3)N_(4))nanosheets were compounded...It is a great challenge to develop membrane materials with high performance and long durability for acidalkaline amphoteric water electrolysis.Hence,the graphitic carbon nitride(g-C_(3)N_(4))nanosheets were compounded with the(2,2'-m-phenylene)-5,5'-benzimidazole(m-PBI)matrix for the preparation of m-PBI/g-C_(3)N_(4) composite membranes.The synthesis of g-C_(3)N_(4) nanosheets and m-PBI matrix have been confirmed by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscoy(TEM)and ^(1)H nuclear magnetic resonance spectra(^(1)H NMR),respectively.The fourier transform infrared spectroscopy(FT-IR)and SEM of the composite membranes showed the g-C_(3)N_(4) nanosheets were well dispersed in the m-PBI/g-C_(3)N_(4) composite membrane.The mechanical properties test exhibited the good mechanical strength,and the TGA curves of m-PBI showed the high thermal stability of composite membranes.Besides,the m-PBI/g-C_(3)N_(4) composite membrane showed excellent proton and hydroxide ion conductivity,which was higher than pure m-PBI and Nafion 115 membrane.The acid-alkaline amphoteric water electrolysis test showed m-PBI/1%g-C_(3)N_(4) composite membrane has the best performance with a current density of 800 mA cm^(-2) at cell voltage of 1.98 V at 20℃.It showed that m-PBI/g-C_(3)N_(4) composite membrane has a good application prospect for acid-alkaline amphoteric water electrolysis.展开更多
In this paper, 1,2,4-triazolium methanesulfonate (C_2H_4N_3^+-CH_3SO_3^-, [Tri][MS]), an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reac...In this paper, 1,2,4-triazolium methanesulfonate (C_2H_4N_3^+-CH_3SO_3^-, [Tri][MS]), an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reached up to 36.51 mS·cm^-1 at 190 ℃. [Tri][MS] was first applied to modify Nation membrane to fabricate [Tri][MS]/Nafion membrane by impregnation method at 150 ℃. The prepared composite membrane showed high thermal stability with decomposed temperature above 200 ℃ in air atmosphere. In addition, the membrane indicated good ionic conductivity with 3.67 mS·cm^-1 at 140 ℃ and reached up to 13.23 mS·cm^-1 at 180 ℃. The structure of the [Tri][MS] and the composite membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry (CV) method. Besides, the [Tri][MS]/Nafion membrane (thickness of 65 μm) was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion membrane was 3.20 mW·cm^-2 at 140 ℃ and 4.90 mW·cm^-2 at 150 ℃, which was much higher than that of Nation membrane.展开更多
The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the fi...The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers.To gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were conducted.Similar to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process.However,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and reliability.The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.展开更多
Proton-exchange membrane fuel cells(PEMFCs)have been widely used commercially to solve the energy crisis and environmental pollution.The oxygen reduction reaction(ORR)at the cathode is the rate-determining step in PEM...Proton-exchange membrane fuel cells(PEMFCs)have been widely used commercially to solve the energy crisis and environmental pollution.The oxygen reduction reaction(ORR)at the cathode is the rate-determining step in PEMFCs.Platinum(Pt)catalysts are used to accelerate the ORR kinetics.Pt’s scarcity,high cost,and instability in an acidic environment at high potentials seriously hinder the commercialization of PEMFCs.Therefore,studies should explore electrocatalysts with high catalytic activity,enhanced stability,and low-Pt loading.This review briefly introduces the research progress on Pt and Pt-based ORR electrocatalysts for PEMFCs,including anticorrosion catalyst supports,Pt,and Pt-based alloy electrocatalysts.Advanced preparation technology and material characterization of Pt-based ORR electrocatalysts are necessary to improve the performance and corresponding reaction mechanisms.展开更多
An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which p...An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which provide more active sites and mass transportation channels.The prepared IrSn electrode showed a cell voltage of 1.96 V at 2.0 A cm^-2 with Ir loading as low as 0.294 mg cm^-2.Furthermore,Ir Sn electrode with different anode catalyst loadings was investigated.The IrS n electrode indicates higher mass current and more stable cell voltage than the commercial Ir Black electrode at low loading.展开更多
The design of the catalyst layer(CL)offers a feasible way to realize the commercialization of proton exchange membrane fuel cells(PEMFCs).An in-depth understanding of catalyst inks is critical to achieving the optimal...The design of the catalyst layer(CL)offers a feasible way to realize the commercialization of proton exchange membrane fuel cells(PEMFCs).An in-depth understanding of catalyst inks is critical to achieving the optimal CL structure and cell performance.In this work,the effects of the solvent evaporation process during ink drying on the formation of the CL microstructure are particularly considered to reveal the structure-property correlations among the catalyst ink,drying process,CL microstructure and fuel cell performance.An increase in the alcohol content of the catalyst ink increases the amount of free ionomers while allowing the ionomer backbone to be more stretched in the dispersion medium.The higher alcohol content contributes to rapid solvent evaporation and thus inhibits the formation of coffee rings;as a result,a more developed ionomer network with a denser pore structure is obtained.Therefore,the alcohol-rich electrode exhibits better proton conduction capability,but higher oxygen transport resistance.For complex fuel cell operating conditions,a catalyst ink formulation with 50 wt%alcohol content is preferred due to its proper ionomer and pore size distribution,providing satisfactory fuel cell performance.展开更多
Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.Th...Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 run.Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area(ECA),and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72(36 mV) under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti0.7Sn0.3O2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.展开更多
Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with ...Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with continuous and high quality recordings and free of influence of solar activities, like magnetic storms. In this investigation, daily recordings from 1 January 2020 to 22 May 2021 have been examined of these both stations. The results show that weak anomalous signals appeared at the beginning of March 2021 with relative low magnitudes of 0.6 nT at Qiaojia station and 0.3 nT at Yongshan station. At the end of this month, the emissions gained an abrupt increase and the amplitudes reached up to 3.8 nT at Qiaojia station and 1.2 nT at Yongsha station. Then, the amplitude decreased to be 0.5 - 1.5 nT and 0.6 - 1.3 nT respectively at both stations but with a high variation frequency in all components. This situation lasted till the Yangbi </span><i><span style="font-family:Verdana;">M</span></i><sub><span style="font-family:Verdana;">S</span></sub><span style="font-family:Verdana;"> 6.4 earthquake happened on May 21, 2021, more than 300 km away from these two ULF observing stations. Totally, the ULF magnetic emissions had been characterized by a synchronous variation in all components at two observing stations.展开更多
Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu na...Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu nanoparticles with the particle size (40 of 3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method. It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction. PtRu/WMC-F7 with D-p > 2d(pt) exhibits the largest electrochemical surface area (ESA) and the highest activity toward methanol electrooxidation. With the decrease in Dp, PtRu/WMC-F30 and PtRu/WMC-F0 have much lower ESA and electrochemical activity, especially for the isopropanol electrooxidation with a larger molecular size. When D-p is more than twice d(pt), the mass transfer of reactants and electrolyte are easier, and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern China.It is important to improve the understanding of seismic hazard assessments in are...As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern China.It is important to improve the understanding of seismic hazard assessments in areas near faults.We start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu Fault.The fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake magnitude.Considering the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation model.Our findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake case.We compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial stress.For the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip rate.The response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.展开更多
基金supported by the National Key Research and Development Program of China(2022YFB4002100)the Key Program of the National Natural Science Foundation of China(22090032,22090030)。
文摘Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis.However,the harsh electrochemical environment of seawater,particularly the presence of aggressive Cl^(-),has been proven to be prone to parasitic chloride ion oxidation and corrosion reactions,thus restricting seawater electrolyzer lifetime.Herein,hierarchical structure(Ni,Fe)O(OH)@NiCoS nanorod arrays(NAs)catalysts with heterointerfaces and localized oxygen vacancies were synthesized at nickel foam substrates via the combination of hydrothermal and annealing methods to boost seawater dissociation.The hiera rchical nanostructure of NiCoS NAs enhanced electrode charge transfer rate and active surface area to accelerate oxygen evolution reaction(OER)and generated sulfate gradient layers to repulsive aggressive Cl^(-).The fabricated heterostructure and vacancies of(Ni,Fe)O(OH)tuned catalyst electronic structure into an electrophilic state to enhance the binding affinity of hydroxyl intermediates and facilitate the structural transformation into amorphousγ-NiFeOOH for promoting OER.Furthermore,through operando electrochemistry techniques,we found that theγ-NiFeOOH possessing an unsaturated coordination environment and lattice-oxygen-participated OER mechanism can minimize electrode Cl^(-)corrosion enabled by stabilizing the adsorption of OH*intermediates,making it one of the best OER catalysts in the seawater medium reported to date.Consequently,these catalysts can deliver current densities of 100 and 500 mA cm-2for boosting OER at minimal overpotentials of 245and 316 mV,respectively,and thus prevent chloride ion oxidation simultaneously.Impressively,a highly stable anion exchange membrane(AEM)seawater electrolyzer based on the non-noble metal heterostructure electrodes reached a record low degradation rate under 100μV h-1at constant industrial current densities of 400 and 600 mA cm-2over 300 h,which exhibits a promising future for the nonprecious and stable AEMWE in the direct seawater electrolysis industry.
基金the National Key R&D Program of China(grants 2017YFC1500501).
文摘The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault,which are adopted from relevant studies such as seismological geology,geodesy,and historical earthquake records.Based on the long-term predictions of large earthquakes throughout the world,this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap,motion strongly locked,sparse small-moderate earthquakes,and apparent Coulomb stress increase.This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland.The present loading rate of each fault is first constrained by geodetic observations;the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.
基金supported by the National Natural Science Foundation of China (NSFC, grant number U2039207)。
文摘The central-southern part of the eastern border of the Sichuan-Yunnan rhombic block provides the research strategy of ‘trade space for time' with an interesting fault system, where the segments have similar focal mechanisms and cover almost continuous spectra of elapse rates. We experiment to study the seismological characteristics of different segments with different elapse rates. We employed the de-clustered earthquake catalog for the calculation of b values for each segment. The analysis revealed that different segments have similar b values,which implies that, although different segments have different periods of earthquake recurrence, the 'natural time' for the whole fault system elapses with a homogeneous pace. We extended the earthquake potential score(EPS)for nowcasting earthquakes to a quasi-EPS(q EPS). It is found that q EPS increases with the increase of elapse rates,albeit for those fault segments whose elapse rates have exceeded 1, q EPS may better reflect the seismic hazard.
基金supported by the National Key Research and Development Program of China (2018YFB1502502)the National Natural Science Foundation of China (22179127)。
文摘Humidity can affect the attenuation of MEA(membrane electrode assembly), however, the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein, we design a simulating automotive protocol, performed on five single fuel cells under RH(relative humidity) 100%,RH 80%, RH 64%, and RH 40%, RH 10%, respectively, to study the relationship of MEA decays and humidity and suggest optimized humidity range to extend the durability. With the electrochemical impedance spectroscopy, cyclic voltammetry, X-ray fluorescence, X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, the four degradation mechanisms about catalyst layer, including Pt dissolution, Pt coarsening, carbon corrosion and ionomer degradation, are observed. Pt coarsening and carbon corrosion are accelerated by higher water content at high humidity. Ionomer degradation and Pt dissolution are enhanced in low humidity. With the linear sweep voltammetry, ion chromatography,nuclear magnetic resonance, tensile test and scan electron microscope, chemical and mechanical degradation in proton exchange membrane are all observed in these five fuels. Chemical degradation, characterized by membrane thinning and more fluoride loss, occurred markedly in RH 10%. Mechanical degradation, characterized by the non-uniformity thickness and bad mechanical properties, is more pronounced in RH 100%, RH 80%, RH 64%. These two degradations are in a moderate level in RH 40%. The research suggests that the RH range from 64% to 40% is conductive to mitigate the degradation of MEAs operated in automotive applications.
基金financially supported by the National Basic Research Program of China (973 Program) (no. 2012CB215500)the National Key Technology Research and Development Program of China (no. 2015BAG06B00)+1 种基金Major Program of the National Natural Science Foundation of China (no. 61433013)National Natural Science Foundation of China (no. 21206012)
文摘Arc ion plating (AIP) is applied to form Ti/(Ti,Cr)N/CrN multilayer coating on the surface of 316L stainless steel (SS316L) as bipolar plates for proton exchange membrane fuel cells (PEMFCs). The characterizations of the coating are analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Interfacial contact resistance (ICR) between the coated sample and carbon paper is 4.9 m Omega cm(2) under 150 N/cm(2), which is much lower than that of the SS316L substrate. Potentiodynamic and potentiostatic tests are performed in the simulated PEMFC working conditions to investigate the corrosion behaviors of the coated sample. Superior anticorrosion performance is observed for the coated sample, whose corrosion current density is 0.12 mu A/cm(2). Surface morphology results after corrosion tests indicate that the substrate is well protected by the multilayer coating. Performances of the single cell with the multilayer coated SS316L bipolar plate are improved significantly compared with that of the cell with the uncoated SS316L bipolar plate, presenting a great potential for PEMFC application. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金supported by the Basic Research Foundation of Institute of Earthquake Science, China Earthquake Administration (02092421)
文摘Significant postseismic deformation of the 2008 M W 7.9 Wenchuan earthquake has been observed from GPS data of the first 14 days after the earthquake. The possible mechanisms for the rapid postseismic deformation are assumed to be afterslip on the earthquake rupture plane and viscoelastic relaxation of coseismiclly stress change in the lower crust or upper mantle. We firstly use the constrained least squares method to find an afterslip model which can fit the GPS data best. The afterslip model can explain near-field data very well but shows considerable discrepancies in fitting far-field data. To estimate the effect due to the viscoelastic relaxation in the lower crust, we then ignore the contribution from the afterslip and attempt to invert the viscosity structure beneath the Longmenshan fault where the Wenchuan earthquake occurred from the postseismic deformation data. For this purpose, we use a viscoelastic model with a 2D geometry based on the geological and seismological observations and the coseismic slip distribution derived from the coseismic GPS and InSAR data. By means of a grid search we find that the optimum viscosity is 9×10 18 Pa·s for the middle-lower crust in the Chengdu Basin, 4×10 17 Pa·s for the middle-lower crust in the Chuanxi Plateau and 7×10 17 Pa·s for the low velocity zone in the Chuanxi plateau. The viscoelastic model explains the postseismic deformation observed in the far-field satisfactorily, but it is considerably worse than the afterslip model in fitting the near-fault data. It suggests therefore a hybrid model including both afterslip and relaxation effects. Since the viscoelastic model produces mainly the far-field surface deformation and has fewer degree of freedoms (three viscosity parameters) than the afterslip model with a huge number of source parameters, we fix the viscositiy structure as obtained before but redetermine the afterslip distribution using the residual data from the viscoelastic modeling. The redetermined afterslip distribution becomes physically more reasonable; it is more localized and exhibits a pattern spatially complementary with the coseismic rupture distribution. We conclude that the aseismic fault slip is responsible for the near-fault postseismic deformation, whereas the viscoelastic stress relaxation might be the major cause for the far-field postseismic deformation.
基金supported by the National Key Research and Development Program of China(2016YFB0101207)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB06050303)the Natural Science Foundation of China(U1664259)
文摘Proton exchange membrane fuel cell(PEMFC) as a power supply device has attracted wide attention in China and abroad for its advantages of high energy density, energy conversion efficiency and zero pollution.With the vigorous support of China's national policy, research institutes and enterprises have carried out extensive and pragmatic work on the basic materials, key components, stacks, auxiliary systems of PEMFCs, as well as the hydrogen station construction in order to realize the wide application of hydrogen energy.PEMFC System and Engineering Research Center of DICP is one of the earliest players in the H2-PEMFCs field.Advances have been achieved in the fields of low-platinum contained catalysts,PEMs, high-efficiency MEAs, low-cost metal bipolar plates, low-temperature and impurity air environment adaptability, stacks and systems.This paper introduces recent progresses of H2-PEMFCs at DICP in key materials, components, stacks, systems and the applications.The engineering status of proton exchange membrane water electrolysis(PEMWE) and the alkaline anion exchange membrane fuel cells(AEMFCs)are also summarized.
基金supported by the National Major Research Project(2016YFB0101208)the National Natural Science Foundation of China(21576257)+1 种基金the Natural Science Foundation-Liaoning United Fund(U1508202)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB06050303)~~
文摘To accelerate the kinetics of the oxygen reduction reaction(ORR)in proton exchange membrane fuel cells,ultrafine Pt nanoparticles modified with trace amounts of cobalt were fabricated and decorated on carbon black through a strategy involving modified glycol reduction and chemical etching.The obtained Pt36Co/C catalyst exhibits a much larger electrochemical surface area(ECSA)and an improved ORR electrocatalytic activity compared to commercial Pt/C.Moreover,an electrode prepared with Pt36Co/C was further evaluated under H2-air single cell test conditions,and exhibited a maximum specific power density of 10.27 W mgPt^-1,which is 1.61 times higher than that of a conventional Pt/C electrode and also competitive with most state-of-the-art Pt-based architectures.In addition,the changes in ECSA,power density,and reacting resistance during the accelerated degradation process further demonstrate the enhanced durability of the Pt36Co/C electrode.The superior performance observed in this work can be attributed to the synergy between the ultrasmall size and homogeneous distribution of catalyst nanoparticles,bimetallic ligand and electronic effects,and the dissolution of unstable Co with the rearrangement of surface structure brought about by acid etching.Furthermore,the accessible raw materials and simplified operating procedures involved in the fabrication process would result in great cost-effectiveness for practical applications of PEMFCs.
基金financially supported by the National Key Research and Development Program of China (Grant no.2016YFB0101208)NSFC-Liaoning Joint Funding (Grant no. U1508202)the National Natural Science Foundations of China (Grant no. 61433013 and 91434131)
文摘The electrode Pt-loading has an effect on the number of active sites and the thickness of catalyst layer,which has huge influence on the mass transfer and water management during dynamic process in PEMFCs. In this study, membrane electrode assemblies with different Pt-loadings were prepared, and PEMFCs were assembled using those membrane electrode assemblies with traditional solid plate and water transport plate as cathode flow-field plates, respectively. The performance and electrochemical surface area of cells were characterized to evaluate the membrane electrode assemblies degradation after rapid currentvariation cycles. Scanning electron microscope and transmission electron microscope were used to investigate the decay of catalyst layers and Pt/C catalyst. With the increase of Pt-loading, the performance degradation of membrane electrode assemblies will be mitigated. But higher Pt-loading means thicker catalyst layer, which leads to a longer pathway of mass transfer, and it may result in carbon material corrosion in membrane electrode assemblies. The decay of Pt/C catalyst in cathode is mainly caused by the corrosion of carbon support, and the degradation of anode Pt/C catalyst is a consequence of migration and aggregation of Pt particles. And using water transport plate is beneficial to alleviating the age of cathode Pt/C catalyst.
基金financially supported by the National Natural Science Fundation of China(No.51125007)the National Basic Research Program(No.2012CB215500)
文摘Pt/WO3/C nanocomposites with parallel WO3 nanorods were synthesized and applied as the cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Electrochemical results and single cell tests show that an enhanced activity for the oxygen reduction reaction (ORR) is obtained for the Pt/WO3/C catalyst compared with Pt/C. The higher catalytic activity might be ascribed to the improved Pt dispersion with smaller particle sizes. The Pt/WO3/C catalyst also exhibits a good electrochemical stability under potential cycling. Thus, the Pt/WO3/C catalyst can be used as a potential PEMFC cathode catalyst.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA21090101)the State Grid Corporation of China(Science and technology project of State Grid Corporation of China,No.SGLNDK00KJJS1900037,No.SGAHDK00YJJS1900079).
文摘It is a great challenge to develop membrane materials with high performance and long durability for acidalkaline amphoteric water electrolysis.Hence,the graphitic carbon nitride(g-C_(3)N_(4))nanosheets were compounded with the(2,2'-m-phenylene)-5,5'-benzimidazole(m-PBI)matrix for the preparation of m-PBI/g-C_(3)N_(4) composite membranes.The synthesis of g-C_(3)N_(4) nanosheets and m-PBI matrix have been confirmed by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscoy(TEM)and ^(1)H nuclear magnetic resonance spectra(^(1)H NMR),respectively.The fourier transform infrared spectroscopy(FT-IR)and SEM of the composite membranes showed the g-C_(3)N_(4) nanosheets were well dispersed in the m-PBI/g-C_(3)N_(4) composite membrane.The mechanical properties test exhibited the good mechanical strength,and the TGA curves of m-PBI showed the high thermal stability of composite membranes.Besides,the m-PBI/g-C_(3)N_(4) composite membrane showed excellent proton and hydroxide ion conductivity,which was higher than pure m-PBI and Nafion 115 membrane.The acid-alkaline amphoteric water electrolysis test showed m-PBI/1%g-C_(3)N_(4) composite membrane has the best performance with a current density of 800 mA cm^(-2) at cell voltage of 1.98 V at 20℃.It showed that m-PBI/g-C_(3)N_(4) composite membrane has a good application prospect for acid-alkaline amphoteric water electrolysis.
基金financially supported by the National Basic Research Program of China(973 ProgramGrant 2012CB215504)the National Natural Science Foundation of China(21203191 and 21306190)
文摘In this paper, 1,2,4-triazolium methanesulfonate (C_2H_4N_3^+-CH_3SO_3^-, [Tri][MS]), an ionic conductor, was successfully synthesized. It exhibited high ionic conductivity of 18.60 mS·cm^-1 at 140 ℃ and reached up to 36.51 mS·cm^-1 at 190 ℃. [Tri][MS] was first applied to modify Nation membrane to fabricate [Tri][MS]/Nafion membrane by impregnation method at 150 ℃. The prepared composite membrane showed high thermal stability with decomposed temperature above 200 ℃ in air atmosphere. In addition, the membrane indicated good ionic conductivity with 3.67 mS·cm^-1 at 140 ℃ and reached up to 13.23 mS·cm^-1 at 180 ℃. The structure of the [Tri][MS] and the composite membrane were characterized by FTIR and the compatibility of [Tri][MS] and Pt/C catalyst was studied by a cyclic voltammetry (CV) method. Besides, the [Tri][MS]/Nafion membrane (thickness of 65 μm) was evaluated with single fuel cell at high temperature and without humidification. The highest power density of [Tri][MS]/Nafion membrane was 3.20 mW·cm^-2 at 140 ℃ and 4.90 mW·cm^-2 at 150 ℃, which was much higher than that of Nation membrane.
基金National Key Point Research and Invention Program of the Thirteenth(Program Nos.2018YFB0105601 and 2017YFB0102801).
文摘The nanofiber electrodes have been considered as promising candidates for commercial proton exchange membrane fuel cells due to their high catalyst utilization and enhanced mass transport efficiency.However,for the first time our research determined that the nanofiber electrodes were restricted by the poor chemical stability of the polymer carriers.To gain further insight into the durability of nanofiber electrodes,both cyclic voltammetry aging tests and Fenton’s tests were conducted.Similar to previous reports,our research demonstrated that nanofiber electrodes showed remarkable stability in the cyclic voltammetry aging process.However,Fenton’s tests indicated that nanofibers in the electrodes would decompose easily while being attacked by reactive oxygen species such as HO·or HOO·,which greatly limits their practicability and reliability.The different performances under the two tests also demonstrated that the cyclic voltammetry aging protocols,which have been applied extensively,cannot well mirror the real operating conditions of fuel cells.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFB1502503)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA21090101)
文摘Proton-exchange membrane fuel cells(PEMFCs)have been widely used commercially to solve the energy crisis and environmental pollution.The oxygen reduction reaction(ORR)at the cathode is the rate-determining step in PEMFCs.Platinum(Pt)catalysts are used to accelerate the ORR kinetics.Pt’s scarcity,high cost,and instability in an acidic environment at high potentials seriously hinder the commercialization of PEMFCs.Therefore,studies should explore electrocatalysts with high catalytic activity,enhanced stability,and low-Pt loading.This review briefly introduces the research progress on Pt and Pt-based ORR electrocatalysts for PEMFCs,including anticorrosion catalyst supports,Pt,and Pt-based alloy electrocatalysts.Advanced preparation technology and material characterization of Pt-based ORR electrocatalysts are necessary to improve the performance and corresponding reaction mechanisms.
基金financially supported by the National Natural Science Foundation of China(U1664259)State Grid Corporation of China(No.SGTYHT/15-JS-191,PEMWE MEA Preparation and degradation mechanism)
文摘An effective oxygen evolution electrode with Ir0.6Sn0.4O2 was designed for proton exchange membrane(PEM)water electrolyzers.The anode catalyst layer exhibits a jagged structure with smaller particles and pores,which provide more active sites and mass transportation channels.The prepared IrSn electrode showed a cell voltage of 1.96 V at 2.0 A cm^-2 with Ir loading as low as 0.294 mg cm^-2.Furthermore,Ir Sn electrode with different anode catalyst loadings was investigated.The IrS n electrode indicates higher mass current and more stable cell voltage than the commercial Ir Black electrode at low loading.
基金financially supported by the National Key Research and Development Program of China(2018YFB1502503)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21090101)。
文摘The design of the catalyst layer(CL)offers a feasible way to realize the commercialization of proton exchange membrane fuel cells(PEMFCs).An in-depth understanding of catalyst inks is critical to achieving the optimal CL structure and cell performance.In this work,the effects of the solvent evaporation process during ink drying on the formation of the CL microstructure are particularly considered to reveal the structure-property correlations among the catalyst ink,drying process,CL microstructure and fuel cell performance.An increase in the alcohol content of the catalyst ink increases the amount of free ionomers while allowing the ionomer backbone to be more stretched in the dispersion medium.The higher alcohol content contributes to rapid solvent evaporation and thus inhibits the formation of coffee rings;as a result,a more developed ionomer network with a denser pore structure is obtained.Therefore,the alcohol-rich electrode exhibits better proton conduction capability,but higher oxygen transport resistance.For complex fuel cell operating conditions,a catalyst ink formulation with 50 wt%alcohol content is preferred due to its proper ionomer and pore size distribution,providing satisfactory fuel cell performance.
基金supported by the National High Technology Research and Development Program of China(863 Program,Grant No.2013AA110201)the National Basic Research Program of China(973 Program,Grant No.2012CB215500)the National Natural Science Foundations of China(Grant No.21203191)
文摘Sn-doped TiO2 nanoparticles with high surface area of 125.7 m2·g-1 are synthesized via a simple one-step hydrothermai method and explored as the cathode catalyst support for proton exchange membrane fuel cells.The synthesized support materials are studied by X-ray diffraction analysis,energy dispersive X-ray spectroscopy and transmission electron microscopy.It is found that the conductivity has been greatly improved by the addition of 30 mol%Sn and Pt nanoparticles are well dispersed on Ti0.7Sn0.3O2 support with an average size of 2.44 run.Electrochemical studies show that the Ti0.7Sn0.3O2 nanoparticles have excellent electrochemical stability under a high potential compared to Vulcan XC-72.The as-synthesized Pt/Ti0.7Sn0.3O2 exhibits high and stable electrocatalytic activity for the oxygen reduction reaction.The Pt/Ti0.7Sn0.3O2 catalyst reserves most of its electrochemically active surface area(ECA),and its half wave potential difference is 11 mV,which is lower than that of Pt/XC-72(36 mV) under 10 h potential hold at 1.4 V vs.NHE.In addition,the ECA degradation of Pt/Ti0.7Sn0.3O2is 1.9 times lower than commercial Pt/XC-72 under 500 potential cycles between 0.6 V and 1.2 V vs.NHE.Therefore,the as synthesized Pt/Ti0.7Sn0.3O2 can be considered as a promising alternative cathode,catalyst for proton exchange membrane fuel cells.
文摘Four ULF (0.01 Hz - 20 Hz) electromagnetic stations had been gradually established and put into service from 2010 to 2011 in Zhaotong area, Yunnan province. Two stations of Qiaojia and Yongshan have been running with continuous and high quality recordings and free of influence of solar activities, like magnetic storms. In this investigation, daily recordings from 1 January 2020 to 22 May 2021 have been examined of these both stations. The results show that weak anomalous signals appeared at the beginning of March 2021 with relative low magnitudes of 0.6 nT at Qiaojia station and 0.3 nT at Yongshan station. At the end of this month, the emissions gained an abrupt increase and the amplitudes reached up to 3.8 nT at Qiaojia station and 1.2 nT at Yongsha station. Then, the amplitude decreased to be 0.5 - 1.5 nT and 0.6 - 1.3 nT respectively at both stations but with a high variation frequency in all components. This situation lasted till the Yangbi </span><i><span style="font-family:Verdana;">M</span></i><sub><span style="font-family:Verdana;">S</span></sub><span style="font-family:Verdana;"> 6.4 earthquake happened on May 21, 2021, more than 300 km away from these two ULF observing stations. Totally, the ULF magnetic emissions had been characterized by a synchronous variation in all components at two observing stations.
基金supported by the National Natural Science Foundation of China (no. 91434106)
文摘Wormholelike mesoporous carbons (WMCs) with three different pore diameters (D-P), namely WMC-F7 (D-p = 8.5 nm), WMC-F30 (D-p =4.4 nm), and WMC-F0 (D-p =3.1 nm) are prepared via a modified sol-gel process. Then PtRu nanoparticles with the particle size (40 of 3.2 nm supported on WMCs are synthesized with a modified pulse microwave-assisted polyol method. It is found that the pore diameter of WMCs plays an important role in the electrochemical activity of PtRu toward alcohol electrooxidation reaction. PtRu/WMC-F7 with D-p > 2d(pt) exhibits the largest electrochemical surface area (ESA) and the highest activity toward methanol electrooxidation. With the decrease in Dp, PtRu/WMC-F30 and PtRu/WMC-F0 have much lower ESA and electrochemical activity, especially for the isopropanol electrooxidation with a larger molecular size. When D-p is more than twice d(pt), the mass transfer of reactants and electrolyte are easier, and thus more PtRu nanoparticles can be utilized and the catalysts activity can be enhanced. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金supported by the National Natural Science Foundation of China(Grant Nos.42125401,42074049)the Anhui Provincial Key Research and Development Program(Grant No.202104a07020016)+2 种基金the University of Science and Technology of China(USTC)Research Funds of the Double First-Class Initiative(Grant No.YD2080000059)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023471)the Joint Open Fund of Mengcheng National Geophysical Observatory(Grant No.MENGO-202101)。
文摘As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern China.It is important to improve the understanding of seismic hazard assessments in areas near faults.We start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu Fault.The fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake magnitude.Considering the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation model.Our findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake case.We compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial stress.For the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip rate.The response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.