The open ratio of a current collector has a great impact on direct methanol fuel cell(DMFC)performance.Although a number of studies have investigated the influence of the open ratio of DMFC current collectors,far too ...The open ratio of a current collector has a great impact on direct methanol fuel cell(DMFC)performance.Although a number of studies have investigated the influence of the open ratio of DMFC current collectors,far too little attention has been given to how geometry(including the shape and feature size of the flow field)affects a current collector with an equal open ratio.In this paper,perforated and parallel current collectors with an equal open ratio of 50%and different feature sizes are designed,and the corresponding experimental results are shown to explain the geometry effects on the output power of the DMFC.The results indicate that the optimal feature sizes are between 2 and 2.5 mm for both perforated and parallel flow field in the current collectors with an equal open ratio of 50%.This means that for passive methanol fuel cells,to achieve the highest output power,the optimal feature size of the flow field in both anode and cathode current collectors is between 2 and 2.5 mm under the operating mode of this experiment.The effects of rib and channel position are also investigated,and the results indicate that the optimum pattern depends on the feature sizes of the flow field.展开更多
Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable comp...Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable components had limitations,including high energy consumption and complicated separation processes.This work suggests a safe hydrometallurgical process to recover usable metallic cobalt from depleted LiCoO_(2)batteries by utilizing citric acid as leachant and hydrogen peroxide as an oxidizing agent,with ethanol as a selective precipitating agent.The anode graphite was also recovered and converted to graphene oxide(GO).The above components were directly resynthesized to cobaltintegrated nitrogen-doped graphene(Co@NG).The Co@NG showed a decent activity towards oxygen reduction reaction(ORR)with a half-wave potential of 0.880 V vs.RHE,almost similar to Pt/C(0.888 V vs.RHE)and with an onset potential of 0.92 V vs.RHE.The metal-nitrogen-carbon(Co-N-C)having the highest nitrogen content has decreased the barrier for ORR since the reaction was enhanced for Co@NG-800,as confirmed by density functional theory(DFT)simulations.The Co@NG cathode catalyst coupled with commercial Pt-Ru/C as anode catalyst exhibits excellent performance for direct methanol fuel cell(DMFC)with a peak power density of 34.7 mW cm^(-2)at a discharge current density of120 m A cm^(-2)and decent stability,indicating the promising utilization of spent battery materials in DMFC applications.Besides,lithium was recovered from supernatant as lithium carbonate by coprecipitation process.This work avoids sophisticated elemental separation by utilizing SLIBs for other renewable energy applications,lowering the environmental concerns associated with recycling.展开更多
Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methano...Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions.Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x(where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity(0.182 S cm^(-1), 80 ℃), water swelling(13.6%, 80 ℃), and methanol permeability(1.6 × 10^(-7)cm~2 s^(-1)). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm^(-2), nearly twice that of Nafion 117(94.2 mW cm^(-2)). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.展开更多
Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fue...Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction.This review focuses on the methanol tolerant noble metal-based electrocatalysts,including platinum and palladium-based alloys,noble metal–carbon based composites,transition metal-based catalysts,carbon-based metal catalysts,and metal-free catalysts.The understanding of the correlation between the activity and the synthesis method,electrolyte environment and stability issues are highlighted.For the transition metal-based catalyst,their activity,stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed.Finally,strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented.This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.展开更多
Sluggish kinetics of methanol oxidation reaction(MOR)and alkaline hydrogen evolution reaction(HER)even on precious Pt catalyst impede the large-scale commercialization of direct methanol fuel cell(DMFC)and water elect...Sluggish kinetics of methanol oxidation reaction(MOR)and alkaline hydrogen evolution reaction(HER)even on precious Pt catalyst impede the large-scale commercialization of direct methanol fuel cell(DMFC)and water electrolysis technologies.Since both of MOR and alkaline HER are related to water dissociation reaction(WDR),it is reasonable to invite secondary active sites toward WDR to pair with Pt for boosted MOR and alkaline HER activity on Pt.Mo_(2)C and Ni species are therefore employed to engineer NiPt-Mo_(2)C active site pairs,which can be encapsulated in carbon cages,via an in-situ self-confinement strategy.Mass activity of Pt in NiPt-Mo_(2)C@C toward HER is boosted to11.3 A mg_(pt)^(-1),33 times higher than that of Pt/C.Similarly,MOR catalytic activity of Pt in NiPt-Mo_(2)C@C is also improved by 10.5 times and the DMFC maximum power density is hence improved by 9-fold.By considering the great stability,NiPt-Mo_(2)C@C exhibits great practical application potential in DMFCs and water electrolysers.展开更多
Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)...Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel cells.The modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/C.Operando in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct pathway.Density functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic performance.This synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.展开更多
This paper introduces the effects of cell operating temperature, methanol concentration and airflow rate, respectively, on the performance of direct methanol fuel cell (DMFC). A novel method based on fuzzy neural ne...This paper introduces the effects of cell operating temperature, methanol concentration and airflow rate, respectively, on the performance of direct methanol fuel cell (DMFC). A novel method based on fuzzy neural networks identification technique is proposed to establish the performance model of DMFC. Three dynamic performance models of DMFC under the influences of cell operating temperature, methanol concentration, and airflow rate are identified and established separately. Simulation results show that modeling using fuzzy neural networks identification is satisfactory with high accuracy. It is applicable to DMFC control systems.展开更多
Abstract: To enable the use of metallic components in direct methanol fuel cells (DMFCs), issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. I...Abstract: To enable the use of metallic components in direct methanol fuel cells (DMFCs), issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated: pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO4^2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.展开更多
Three co-impregnation/chemical reduction methods in acidic solutions of pH 〈 1,including ethylene glycol (EG),NaBH4,and HCOOH,were compared for Pt-WO3/C catalysts.Pt-WO3/C catalysts containing 10 wt.% and 20 wt.% p...Three co-impregnation/chemical reduction methods in acidic solutions of pH 〈 1,including ethylene glycol (EG),NaBH4,and HCOOH,were compared for Pt-WO3/C catalysts.Pt-WO3/C catalysts containing 10 wt.% and 20 wt.% platinum per carbon were prepared by the three methods; their morphology and electrocatalytic activities were characterized.The 20 wt.% Pt-WO3/C catalyst prepared by the co-impregnation/EG method presented the optimal dispersion with an average particle size of 4.6 nm and subsequently the best electrocatalytic activity,and so,it was further characterized.Its anodic peak current density for ethanol oxidation from linear sweep voltammetry (LSV) is 7.9 mA·cm^-2,which is 1.4 and 5.2 times as high as those of the catalysts prepared by co-impregnation/NaBH4 and co-impregnation/ HCOOH reduction methods,2.1 times as high as that of the 10 wt.% Pt-WO3/C catalyst prepared by co-impregnation/EG method,respectively.展开更多
To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells,carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the prepa...To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells,carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method.The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction (XRD),transmission electron microscopy (TEM),X-ray photoelectron spectroscopy (XPS),and infrared spectroscopy of adsorbed probe ammonia molecules.The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique.The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes.It is explained that,the structure,the oxidation states,and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoOx to the Pt-based catalysts.展开更多
Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for t...Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for the commercialization of DLFCs is the high loading requirement of platinum group metals(PGMs) as catalysts. Atomically dispersed catalysts(ADCs) have been brought into recent focus for DLFCs due to their well-defined active sites, high selectivity, maximal atom-utilization, and anti-poisoning property. In this review, we summarized the structure–property relationship for unveiling the underlying mechanisms of ADCs for DLFCs. More specifically, different types of fuels used in DLFCs such as methanol, formic acid,and ethanol were discussed. At last, we highlighted current challenges, research directions, and future outlooks towards the practical application of DLFCs.展开更多
A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxi...A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide (NAD +) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD + compared with those in the absence of NAD +. The catalytic activity of NAD + is sensitive to temperature. When the temperature preponderates over 45℃, NAD + is out of function of catalysis for methanol oxidation, which is probably due to the denaturation of NAD + at a relatively high temperature.展开更多
Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and cyclic voltammograms (CVs) were ...Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and cyclic voltammograms (CVs) were carried out to characterize the morphology, composition and the electrochemical properties of the PtRu/C catalyst. The results revealed that the PtRu nanoparticles with small average particle size (≈2.5 nm), and highly dispersed on the carbon support. The PtRu/C catalyst exhibited high catalytic activity and anti poisoned performance than that of the JM PtRu/C. It is imply that the modified polyol method is efficient for PtRu/C catalyst preparation.展开更多
A sulfonated poly(ether ether ketone)(SPEEK) membrane with a fairly high degree of sulfonation(DS) can swell excessively and even dissolve at high temperature.To solve these problems,insolvable functionalized silica p...A sulfonated poly(ether ether ketone)(SPEEK) membrane with a fairly high degree of sulfonation(DS) can swell excessively and even dissolve at high temperature.To solve these problems,insolvable functionalized silica powder with sulfonic acid groups(SiOx-S) was added into the SPEEK matrix(DS = 55.1%) to prepare SPEEK/SiOx-S composite membranes.The decrease in both the swelling degree and the methanol permeability of the membranes was a dose-dependent result of addition of the SiOx-S powder.Pure SPEEK membrane swelled 52.6% at 80°C,whereas the SPEEK/SiOx-S(15%,by mass) membrane swelled only 27.3% at the same temperature.From room temperature to 80℃,all SPEEK/SPEEK/SiOx-S composite membranes had methanol permeability of about o ne order of magnitude lower than that of Nafion?115.Compared with pure SPEEK membranes,the addition of the SiOx-S powder not only leads to higher proton conductivity,but also increases the dimensional stability at higher temperatures,and greater proton conductivity can be achieved at higher temperature.The SPEEK/SiOx-S(20%,by mass) membrane could withstand temperature up to 145°C,at which in 100% relative humidity(RH) its proton conductivity exceeded slightly that of Nafion?115 membrane and reached 0.17 S·cm-1,while pure SPEEK membrane dissolved at 90°C.The SPEEK/SiOx-S composite membranes are promising for use in direct methanol fuel cells because of their good dimensional stability,high proton conductivity,and low methanol permeability.展开更多
This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell(DIR-SOFC) comprehensively.A one-dimensional dynamic model of a planar DIR-SOFC is first developed bas...This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell(DIR-SOFC) comprehensively.A one-dimensional dynamic model of a planar DIR-SOFC is first developed based on mass and energy balances,and electrochemical principles.Further,a solution strategy is presented to solve the model,and the International Energy Agency(IEA) benchmark test is used to validate the model.Then,through model-based simulations,the steady-state performance of a co-flow planar DIR-SOFC under specified initial operating conditions and its dynamic response to introduced operating parameter disturbances are studied.The dynamic responses of important SOFC variables,such as cell temperature,current density,and cell voltage are all investigated when the SOFC is subjected to the step-changes in various operating parameters including both the load current and the inlet fuel and air flow rates.The results indicate that the rapid dynamics of the current density and the cell voltage are mainly influenced by the gas composition,particularly the H2 molar fraction in anode gas channels,while their slow dynamics are both dominated by the SOLID(including the PEN and interconnects) temperature.As the load current increases,the SOLID temperature and the maximum SOLID temperature gradient both increase,and thereby,the cell breakdown is apt to occur because of excessive thermal stresses.Changing the inlet fuel flow rate might lead to the change in the anode gas composition and the consequent change in the current density distribution and cell voltage.The inlet air flow rate has a great impact on the cell temperature distribution along the cell,and thus,is a suitable manipulated variable to control the cell temperature.展开更多
Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equ...Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.展开更多
Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells (DMFCs). A house-made plasma sputtering system was used to deposit platinum of 0.1 mg...Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells (DMFCs). A house-made plasma sputtering system was used to deposit platinum of 0.1 mg/cm^2 onto un-catalyzed gas diffusion layers (GDLs) to form a Pt catalyzed cathode at different radio frequency (RF) powers and sputtering-gas pressures. The sputtered cathodes were assembled in custom-made membrane electrode assemblies (MEAs) with a commercial anode and tested for the electrical performance of the single cell. A custommade MEA with a sputtering prepared cathode was compared with that of a reference membrane electrode assembly made of commercial JM (Johnson Mattey) catalysts (Pt loading per electrode of 0.5 mg/cm^2) under passive methanol supply, ambient temperature and air-breathing conditions. The results showed that the cathode prepared at an input power of 110 W and sputtering-gas pressure of 5.3 Pa exhibited the best cell performance and highest Pt utilization efficiency, which was due to the miniaturization of the Pt particles and formation of the porous catalyst layer. Although the single cell performance of the commercial cathode was better than all the sputtering fabricated cathodes, the Pt utilization efficiency of all the sputtered cathodes was higher than that of the commercial cathode.展开更多
Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of ...Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure. The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.展开更多
It was established that application of bipolar membrane in a direct borohydride fuel cell (DBFC) with H2O2 co-generation enabled to keep constant pH in catholyte within 2.5 - 3.2 limits, which allowed us to carry out ...It was established that application of bipolar membrane in a direct borohydride fuel cell (DBFC) with H2O2 co-generation enabled to keep constant pH in catholyte within 2.5 - 3.2 limits, which allowed us to carry out treatment of water polluted by organic compounds in fuel cell catholyte. Treatment of water was carried out by electro-Fenton and photo-electro-Fenton methods. With the view of efficiency, photo-electro-Fenton method of treatment was the most efficient, which enabled to decrease COD of catholytes containing (in each case) phenol, valsaren, 400 g/L dymethoate (BI-58) and valsaciper from 500 ppm to 30, 11, 9 and 3 ppm, respectively after 180 min treatment. By increasing the catholyte temperature from 20℃?to 40℃?in the same period, phenol COD fell to 5 ppm.展开更多
Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fu...Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).展开更多
基金supported by the National Natural Science Foundation of China (No.51405342)Natural Science Foundation of Tianjin (No.20JCYBJC00050)Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology.
文摘The open ratio of a current collector has a great impact on direct methanol fuel cell(DMFC)performance.Although a number of studies have investigated the influence of the open ratio of DMFC current collectors,far too little attention has been given to how geometry(including the shape and feature size of the flow field)affects a current collector with an equal open ratio.In this paper,perforated and parallel current collectors with an equal open ratio of 50%and different feature sizes are designed,and the corresponding experimental results are shown to explain the geometry effects on the output power of the DMFC.The results indicate that the optimal feature sizes are between 2 and 2.5 mm for both perforated and parallel flow field in the current collectors with an equal open ratio of 50%.This means that for passive methanol fuel cells,to achieve the highest output power,the optimal feature size of the flow field in both anode and cathode current collectors is between 2 and 2.5 mm under the operating mode of this experiment.The effects of rib and channel position are also investigated,and the results indicate that the optimum pattern depends on the feature sizes of the flow field.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)the South Korea grant funded by the Korean government(MSIT)(2021R1A4A2000934,2023R1A2C3004336)+1 种基金The computational part of the work was supported by Department of Chemical and Biomolecular Engineering,Institute of Emergent Materials,Sogang University,via NRF Korea grant 2015M3D3A1A01064929a generous supercomputing time from KISTI。
文摘Recycling spent lithium-ion batteries(SLIBs)has become essential to preserve the environment and reclaim vital resources for sustainable development.The typical SLIBs recycling concentrated on separating valuable components had limitations,including high energy consumption and complicated separation processes.This work suggests a safe hydrometallurgical process to recover usable metallic cobalt from depleted LiCoO_(2)batteries by utilizing citric acid as leachant and hydrogen peroxide as an oxidizing agent,with ethanol as a selective precipitating agent.The anode graphite was also recovered and converted to graphene oxide(GO).The above components were directly resynthesized to cobaltintegrated nitrogen-doped graphene(Co@NG).The Co@NG showed a decent activity towards oxygen reduction reaction(ORR)with a half-wave potential of 0.880 V vs.RHE,almost similar to Pt/C(0.888 V vs.RHE)and with an onset potential of 0.92 V vs.RHE.The metal-nitrogen-carbon(Co-N-C)having the highest nitrogen content has decreased the barrier for ORR since the reaction was enhanced for Co@NG-800,as confirmed by density functional theory(DFT)simulations.The Co@NG cathode catalyst coupled with commercial Pt-Ru/C as anode catalyst exhibits excellent performance for direct methanol fuel cell(DMFC)with a peak power density of 34.7 mW cm^(-2)at a discharge current density of120 m A cm^(-2)and decent stability,indicating the promising utilization of spent battery materials in DMFC applications.Besides,lithium was recovered from supernatant as lithium carbonate by coprecipitation process.This work avoids sophisticated elemental separation by utilizing SLIBs for other renewable energy applications,lowering the environmental concerns associated with recycling.
基金supported by the program of Jilin Provincial Department of Science and Technology (YDZJ202301ZYTS320)。
文摘Direct methanol fuel cells(DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes(PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions.Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x(where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity(0.182 S cm^(-1), 80 ℃), water swelling(13.6%, 80 ℃), and methanol permeability(1.6 × 10^(-7)cm~2 s^(-1)). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm^(-2), nearly twice that of Nafion 117(94.2 mW cm^(-2)). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.
基金supported by the National Natural Science Foundations of China(22150410340)the Chongqing Science&Technology Commission(catc2018jcyjax0582)。
文摘Methanol cross-over effects from the anode to the cathode are important parameters for reducing catalytic performance in direct methanol fuel cells.A promising candidate catalyst for the cathode in direct methanol fuel cells must have excellent activity toward oxygen reduction reaction and resistance to methanol oxidation reaction.This review focuses on the methanol tolerant noble metal-based electrocatalysts,including platinum and palladium-based alloys,noble metal–carbon based composites,transition metal-based catalysts,carbon-based metal catalysts,and metal-free catalysts.The understanding of the correlation between the activity and the synthesis method,electrolyte environment and stability issues are highlighted.For the transition metal-based catalyst,their activity,stability and methanol tolerance in direct methanol fuel cells and comparisons with those of platinum are particularly discussed.Finally,strategies to enhance the methanol tolerance and hinder the generation of mixed potential in direct methanol fuel cells are also presented.This review provides a perspective for future developments for the scientist in selecting suitable methanol tolerate catalyst for oxygen reduction reaction and designing high-performance practical direct methanol fuel cells.
基金financial support from the National Natural Science Foundation of China(Nos.21875224,22179121)the Fundamental Research Founds for National University,China University of Geosciences(Wuhan)。
文摘Sluggish kinetics of methanol oxidation reaction(MOR)and alkaline hydrogen evolution reaction(HER)even on precious Pt catalyst impede the large-scale commercialization of direct methanol fuel cell(DMFC)and water electrolysis technologies.Since both of MOR and alkaline HER are related to water dissociation reaction(WDR),it is reasonable to invite secondary active sites toward WDR to pair with Pt for boosted MOR and alkaline HER activity on Pt.Mo_(2)C and Ni species are therefore employed to engineer NiPt-Mo_(2)C active site pairs,which can be encapsulated in carbon cages,via an in-situ self-confinement strategy.Mass activity of Pt in NiPt-Mo_(2)C@C toward HER is boosted to11.3 A mg_(pt)^(-1),33 times higher than that of Pt/C.Similarly,MOR catalytic activity of Pt in NiPt-Mo_(2)C@C is also improved by 10.5 times and the DMFC maximum power density is hence improved by 9-fold.By considering the great stability,NiPt-Mo_(2)C@C exhibits great practical application potential in DMFCs and water electrolysers.
基金supported by the National Natural Science Foundation of China(21571038,22035004)the Education Department of Guizhou Province(2021312)+2 种基金the Foundation of Guizhou Province(2019-5666)the National Key R&D Program of China(2017YFA0700101)the State Key Laboratory of Physical Chemistry of Solid Surfaces(Xiamen University,202009)。
文摘Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel cells.The modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/C.Operando in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct pathway.Density functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic performance.This synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.
基金Project supported by the National High-Technology Research and Development Program Foundation of China(Grant No.2003AA517020)
文摘This paper introduces the effects of cell operating temperature, methanol concentration and airflow rate, respectively, on the performance of direct methanol fuel cell (DMFC). A novel method based on fuzzy neural networks identification technique is proposed to establish the performance model of DMFC. Three dynamic performance models of DMFC under the influences of cell operating temperature, methanol concentration, and airflow rate are identified and established separately. Simulation results show that modeling using fuzzy neural networks identification is satisfactory with high accuracy. It is applicable to DMFC control systems.
基金financially supported by the Natural Science Foundation of Guangdong Province, China (No. S2013040016899)the Fundamental Research Funds for Central Universities of China (No. 2013ZM0003)+1 种基金the National Natural Science Foundation of China (No. 51275180)the Open Fund of Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures (No. 2013001)
文摘Abstract: To enable the use of metallic components in direct methanol fuel cells (DMFCs), issues related to corrosion resistance must be considered because of an acid environment induced by the solid electrolyte. In this study, we report the electrochemical behaviors of metal-fiber-based porous sintered components in a simulated corrosive environment of DMFCs. Three materials were evaluated: pure copper, AISI304, and AISI316L. The environmental factors and related mechanisms affecting the corrosion behaviors were analyzed. The results demonstrated that AISI316L exhibits the best performance. A higher SO4^2- concentration increases the risk of material corrosion, whereas an increase in methanol concentration inhibits corrosion. The morphological features of the corroded samples were also characterized in this study.
基金supported by the National Basic Research and Development Program of China (No. 2009CB220100)Beijing Excellent Talent Support Program (No. 20071D1600300396)
文摘Three co-impregnation/chemical reduction methods in acidic solutions of pH 〈 1,including ethylene glycol (EG),NaBH4,and HCOOH,were compared for Pt-WO3/C catalysts.Pt-WO3/C catalysts containing 10 wt.% and 20 wt.% platinum per carbon were prepared by the three methods; their morphology and electrocatalytic activities were characterized.The 20 wt.% Pt-WO3/C catalyst prepared by the co-impregnation/EG method presented the optimal dispersion with an average particle size of 4.6 nm and subsequently the best electrocatalytic activity,and so,it was further characterized.Its anodic peak current density for ethanol oxidation from linear sweep voltammetry (LSV) is 7.9 mA·cm^-2,which is 1.4 and 5.2 times as high as those of the catalysts prepared by co-impregnation/NaBH4 and co-impregnation/ HCOOH reduction methods,2.1 times as high as that of the 10 wt.% Pt-WO3/C catalyst prepared by co-impregnation/EG method,respectively.
基金supported by the International Science and Technology Cooperation Program of China (No. 2006DFA61240)
文摘To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells,carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method.The physicochemical characterizations of the catalysts were carried out by using X-ray diffraction (XRD),transmission electron microscopy (TEM),X-ray photoelectron spectroscopy (XPS),and infrared spectroscopy of adsorbed probe ammonia molecules.The electrocatalytic properties of the catalysts for methanol oxidation were investigated by the cyclic voltammetry technique.The results show that Pt-Mo/CNTs@TiO2 electrode exhibits the highest performance in all the electrodes.It is explained that,the structure,the oxidation states,and the acid-base properties of the catalysts are influenced due to the strong interaction between Ti and Mo species by adding TiO2 and MoOx to the Pt-based catalysts.
基金financial supports from the National Science Foundation under Grant Nos. CBET-1949840 and CMMI-1851674financial support from the Preeminent Postdoctoral Program (P3) of the University of Central Florida。
文摘Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for the commercialization of DLFCs is the high loading requirement of platinum group metals(PGMs) as catalysts. Atomically dispersed catalysts(ADCs) have been brought into recent focus for DLFCs due to their well-defined active sites, high selectivity, maximal atom-utilization, and anti-poisoning property. In this review, we summarized the structure–property relationship for unveiling the underlying mechanisms of ADCs for DLFCs. More specifically, different types of fuels used in DLFCs such as methanol, formic acid,and ethanol were discussed. At last, we highlighted current challenges, research directions, and future outlooks towards the practical application of DLFCs.
文摘A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide (NAD +) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD + compared with those in the absence of NAD +. The catalytic activity of NAD + is sensitive to temperature. When the temperature preponderates over 45℃, NAD + is out of function of catalysis for methanol oxidation, which is probably due to the denaturation of NAD + at a relatively high temperature.
文摘Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and cyclic voltammograms (CVs) were carried out to characterize the morphology, composition and the electrochemical properties of the PtRu/C catalyst. The results revealed that the PtRu nanoparticles with small average particle size (≈2.5 nm), and highly dispersed on the carbon support. The PtRu/C catalyst exhibited high catalytic activity and anti poisoned performance than that of the JM PtRu/C. It is imply that the modified polyol method is efficient for PtRu/C catalyst preparation.
基金Supported by the State Key Development Program for Basic Research of China (2008CB617502), the National Natural Science Foundation of China (20606025), and Program for Changjiang Scholars and Innovative Research Team in University of China (IRT0641).
文摘A sulfonated poly(ether ether ketone)(SPEEK) membrane with a fairly high degree of sulfonation(DS) can swell excessively and even dissolve at high temperature.To solve these problems,insolvable functionalized silica powder with sulfonic acid groups(SiOx-S) was added into the SPEEK matrix(DS = 55.1%) to prepare SPEEK/SiOx-S composite membranes.The decrease in both the swelling degree and the methanol permeability of the membranes was a dose-dependent result of addition of the SiOx-S powder.Pure SPEEK membrane swelled 52.6% at 80°C,whereas the SPEEK/SiOx-S(15%,by mass) membrane swelled only 27.3% at the same temperature.From room temperature to 80℃,all SPEEK/SPEEK/SiOx-S composite membranes had methanol permeability of about o ne order of magnitude lower than that of Nafion?115.Compared with pure SPEEK membranes,the addition of the SiOx-S powder not only leads to higher proton conductivity,but also increases the dimensional stability at higher temperatures,and greater proton conductivity can be achieved at higher temperature.The SPEEK/SiOx-S(20%,by mass) membrane could withstand temperature up to 145°C,at which in 100% relative humidity(RH) its proton conductivity exceeded slightly that of Nafion?115 membrane and reached 0.17 S·cm-1,while pure SPEEK membrane dissolved at 90°C.The SPEEK/SiOx-S composite membranes are promising for use in direct methanol fuel cells because of their good dimensional stability,high proton conductivity,and low methanol permeability.
基金Supported by the National High Technology Research and Development Program of China (2006AA05Z148)
文摘This article aims to investigate the transient behavior of a planar direct internal reforming solid oxide fuel cell(DIR-SOFC) comprehensively.A one-dimensional dynamic model of a planar DIR-SOFC is first developed based on mass and energy balances,and electrochemical principles.Further,a solution strategy is presented to solve the model,and the International Energy Agency(IEA) benchmark test is used to validate the model.Then,through model-based simulations,the steady-state performance of a co-flow planar DIR-SOFC under specified initial operating conditions and its dynamic response to introduced operating parameter disturbances are studied.The dynamic responses of important SOFC variables,such as cell temperature,current density,and cell voltage are all investigated when the SOFC is subjected to the step-changes in various operating parameters including both the load current and the inlet fuel and air flow rates.The results indicate that the rapid dynamics of the current density and the cell voltage are mainly influenced by the gas composition,particularly the H2 molar fraction in anode gas channels,while their slow dynamics are both dominated by the SOLID(including the PEN and interconnects) temperature.As the load current increases,the SOLID temperature and the maximum SOLID temperature gradient both increase,and thereby,the cell breakdown is apt to occur because of excessive thermal stresses.Changing the inlet fuel flow rate might lead to the change in the anode gas composition and the consequent change in the current density distribution and cell voltage.The inlet air flow rate has a great impact on the cell temperature distribution along the cell,and thus,is a suitable manipulated variable to control the cell temperature.
基金Supported by the National High Technology Research and Development Program of China (2007AA05Z150) the National Natural Science Foundation of China (50911140287 50973055)
文摘Electrochemical impedance spectroscopy (EIS) is widely used in fuel cell impedance analysis. However, for ohmic resistance (R Ω), EIS has some disadvantages such as long test period and complex data analysis with equivalent circuits. Therefore, the current interruption method is explored to measure the value of RΩ in direct methanol fuel cells (DMFC) at different temperatures and current densities. It is found that RΩ decreases as temperature increase, and decreases initially and then increases as current density increases. These results are consistent with those measured by the EIS technique. In most cases, the ohmic resistances with current interruption (R iR ) are larger than those with EIS (R EIS ), but the difference is small, in the range from –0.848% to 5.337%. The errors of R iR at high current densities are less than those of R EIS . Our results show that the R iR data are reliable and easy to obtain in the measurement of ohmic resistance in DMFC.
基金supported by National Natural Science Foundation of China (No. 10975162)the Principal Foundation of Institute of Plasma PhysicsChinese Academy of Sciences (No. 095GZ1156Y)
文摘Plasma sputtering deposition techniques are good candidates for the fabrication of electrodes used for direct methanol fuel cells (DMFCs). A house-made plasma sputtering system was used to deposit platinum of 0.1 mg/cm^2 onto un-catalyzed gas diffusion layers (GDLs) to form a Pt catalyzed cathode at different radio frequency (RF) powers and sputtering-gas pressures. The sputtered cathodes were assembled in custom-made membrane electrode assemblies (MEAs) with a commercial anode and tested for the electrical performance of the single cell. A custommade MEA with a sputtering prepared cathode was compared with that of a reference membrane electrode assembly made of commercial JM (Johnson Mattey) catalysts (Pt loading per electrode of 0.5 mg/cm^2) under passive methanol supply, ambient temperature and air-breathing conditions. The results showed that the cathode prepared at an input power of 110 W and sputtering-gas pressure of 5.3 Pa exhibited the best cell performance and highest Pt utilization efficiency, which was due to the miniaturization of the Pt particles and formation of the porous catalyst layer. Although the single cell performance of the commercial cathode was better than all the sputtering fabricated cathodes, the Pt utilization efficiency of all the sputtered cathodes was higher than that of the commercial cathode.
基金The project is supported by the National Natural Science Foundation of China (20576023)the Science and Technology Project of Guangzhou City (2005 J1-C0361)the Key Project of Education Bureau of Guangzhou City (2052).
文摘Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure. The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.
文摘It was established that application of bipolar membrane in a direct borohydride fuel cell (DBFC) with H2O2 co-generation enabled to keep constant pH in catholyte within 2.5 - 3.2 limits, which allowed us to carry out treatment of water polluted by organic compounds in fuel cell catholyte. Treatment of water was carried out by electro-Fenton and photo-electro-Fenton methods. With the view of efficiency, photo-electro-Fenton method of treatment was the most efficient, which enabled to decrease COD of catholytes containing (in each case) phenol, valsaren, 400 g/L dymethoate (BI-58) and valsaciper from 500 ppm to 30, 11, 9 and 3 ppm, respectively after 180 min treatment. By increasing the catholyte temperature from 20℃?to 40℃?in the same period, phenol COD fell to 5 ppm.
基金financialy supported by the National Key R&D Program of China(No.2018YFB1502303)the National Natural Science Foundation of China(No.21722601,U19A2017)China Postdoctoral Science Foundation(No.2019M660389)。
文摘Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).