In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by io...In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by ion morphology pretreatme nt and solvent extraction.An acidic V(Ⅴ)/W(Ⅵ)solution was obtained using the me mbrane electrolysis method without adding any other chemical reagents.In addition,Na was recovered in the form of NaOH by product,avoiding the generation of Na containing wastewater.The electrolysis parameters were investigated,the lowest power consumption of 3063 kW·h·t^(-1)NaOH was obtained at a current density of 125 A·m^(-2)and an initial NaOH concentration of 2 mol·L^(-1).After electrolysis,oxalic acid was added to the acidic V/W containing solution,converting V(Ⅴ)negative ion to V(Ⅳ)positive ion.Since W(Ⅵ)ion state remained in negative form,the generation of heteropolyacid ions(W_(x)V_(y)O_(z)^(n-))was prevented.It was found that under the condition of oxalic acid addition/theoretical consumption 1.2 and reaction temperature 75℃,100%V(Ⅴ)was co nverted to V(Ⅳ4).Using 10%N263+10%noctanol+80%sulfonated kerosene as extractant,the highest W(Ⅵ)/V(Ⅳ)separation coefficient of 7559.76was obtained at pH=1.8,O:A ratio=1:1 and extraction time 15 min.With 2 mol·L^(-1)NaOH as stripping reagent,the W stripping efficiency reached 98.50%at O:A ratio=2:1 after 4-stages of stripping.The enrichment of V remained in the solution was realized using P204 as extractant and 20%(mass)H_(2)SO_(4)as stripping reagent.The parameters of extraction/stripping process were investigated,using 10%P204+10%TBP+80%sulfonated kerosene as extractant,the V extraction efficiency reached 97.50%at O:A ratio=1:2after 4 stages of extraction.Using 20%H_(2)SO_(4)as the stripping reagent,the V stripping efficiency was 98.30%at an O:A ratio of 4:1 after five stage s of stripping.After the entire process,a high-purity VOSO_(4)and Na_(2)WO_(4)product solutions were obtained with V/W recovery efficiency 95.84%/98.50%,separately.This study examined a more effective and cleaner method for separating V/W/Na in Na_(2)WO_(4)/NaVO_(3)solution,which may serve as a reference for the separation and recovery of V/W/Na in waste SCR catalysts.展开更多
A new method for the direct synthesis of Li2CO3 powders by membrane electrolysis from LiC1 solution is demonstrated in this paper, where a novel electrolysis system combining ventilation, agitation and loop filtration...A new method for the direct synthesis of Li2CO3 powders by membrane electrolysis from LiC1 solution is demonstrated in this paper, where a novel electrolysis system combining ventilation, agitation and loop filtration functions was reported. The aim of this work is to explore the effect of the starting concentration of LiC1 on the phase and micromorphology of Li2CO3 crystals and thereafter to explore the mechanism of crystallization and grain growth law. Scanning electron microscopy （SEM） images indicate that the particles become irregular polycrystalline from well-defined flower-like and the micro-crystals change from lamellar to needle-like and subsequently to smaller globular granules, and the surface of the crystals becomes smooth with LiC1 concentration increasing from 50 to 400 g.L^-3. The crystalline phases of the different samples were characterized using powder X-ray diffraction （XRD） and the results prove that pure LiaCO3 crystals can be obtained in a single step by the electrolysis method. The particle size distributions show that both volume mean crystal sizes and the full width at half maximum （FWHM） decrease when the starting LiC1 concentration increases from 50 to 300 g.L 3 and also decreases from 400 to 300 g-L^-3.展开更多
The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widesp...The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widespread adoption is hindered by the high cost and non-optimised design of crucial components,such as porous transport layers(PTL)and flow fields.This study comprehensively investigates the interplay between structure,mechanics,and electrochemical performance of a low-cost knitted wire mesh PTL,focusing on its potential to enhance cell assembly and operation.Electrochemical characterisation was performed on a single 4 cm^(2)cell,using 1M KOH at 60℃.Knitted wire mesh PTL,characterised by approximately 70%porosity,2mm thickness,and 1.098 tortuosity,delivered a 33%improvement in current density compared to the standard cell configuration.Introducing a knitted PTL interlayer reduced cell voltage by 74 mV at 2 A cm^(−2)by improving compression force distribution across the active area,enhancing gas transport and maintaining optimal electrical and thermal conductivity.These findings highlight the significant potential of innovative PTL designs in AEMWE to improve mechanical and operational efficiency without increasing the cost.展开更多
Despite the cost and activity advantages,ruthenium-based oxygen evolution reaction(OER)catalysts face severe stability problems for proton exchange membrane water electrolysis(PEM-WE)due to Ru dissolution.Although tre...Despite the cost and activity advantages,ruthenium-based oxygen evolution reaction(OER)catalysts face severe stability problems for proton exchange membrane water electrolysis(PEM-WE)due to Ru dissolution.Although tremendous attention has been paid to enhancing the stability and activity under small current density in three electrode systems,there still lacks validation under industrial current density at the device level.Aiming at this issue,we report highly active and durable ruthenium-iridium alloyed oxides(IrRuO_(x))as the acidic OER catalyst for PEM-WE with exceptional durability for 1600 h at an industrial current density of 2.0 A·cm^(−2).X-ray absorption spectroscopy reveals that the introduction of iridium modulates the electronic structure of Ru and strengthens the local Ru–O bonds in RuO_(2),which is crucial for ensuring activity and stability.As a result,in comparison with its RuO_(2) counterpart,IrRuO_(x) works stably against the Ru leaching-induced catalytic layer breakage during the stability test.This work demonstrates the great potential of IrRuO_(x) as the practical OER catalyst for the application in PEM-WE.展开更多
Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production...Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production costs and the need for efficient large-scale production technologies remain significant obstacles. Among the various hydrogen production methods, water electrolysis stands out due to its environmentally friendly nature and the high purity of hydrogen produced. Proton exchange membrane(PEM) electrolyzers are promising devices for hydrogen production. They exhibit the superiorities in high operational current densities exceeding 2 A cm^(-2), greater resistance to fluctuations, and improved electrolysis efficiency. A critical component of PEM water electrolyzers is the porous transport layer(PTL), which serves as an electron conductor between the membrane electrode assembly and the bipolar plate, ensuring efficient mass transport between gas and liquid phases. This review provides a comprehensive examination of PTL materials,structural configurations, surface treatments, and the resulting performance of electrolytic cells. These insights aim to guide researchers in selecting appropriate PTL materials and treatments tailored to specific practical applications. Additionally, this paper analyzes operational conditions—such as compaction pressure, temperature,water flow rate, and oxygen saturation within the electrolyzer—that influence PTL performance. These factors are crucial for researchers to holistically design and optimize PEM electrolyzer systems.展开更多
A three-dimensional, non-isothermal, two-phase model for a PEM water electrolysis cell(PEMEC) is established in this study.An effective connection between two-phase transport and performance in the PEMECs is built thr...A three-dimensional, non-isothermal, two-phase model for a PEM water electrolysis cell(PEMEC) is established in this study.An effective connection between two-phase transport and performance in the PEMECs is built through coupling the liquid water saturation and temperature in the charge conservation equation. The distributions of liquid water and temperature with different operating(voltage, temperature, inlet velocity) and physical(contact angle, and porosity of anode gas diffusion layer) parameters are examined and discussed in detail. The results show that the water and temperature distributions, which are affected by the operating and physical parameters, have a combined effect on the cell performance. The effects of various parameters on the PEMEC are of interaction and restricted mutually. As the voltage increases, the priority factor caused by the change of inlet water velocity changes from the liquid water saturation increase to the temperature drop in the anode catalyst layer. While the priority influence factor caused by the contact angle and porosity of anode gas diffusion layer is the liquid water saturation. Decreasing the contact angle or/and increasing the porosity can improve the PEMEC performance especially at the high voltage. The results can provide a better understanding of the effect of heat and mass transfer and the foundation for optimization design.展开更多
The flow field structure on the bipolar plate significantly affects the performance of the proton exchange membrane electrolysis cell(PEMEC).This paper proposes a new interdigitated-jet hole flow field(JHFF)design to ...The flow field structure on the bipolar plate significantly affects the performance of the proton exchange membrane electrolysis cell(PEMEC).This paper proposes a new interdigitated-jet hole flow field(JHFF)design to improve the uniformities of liquid saturation,temperature,and current density distributions.The common single-path serpentine flow field(SSFF)and interdigitated flow field(IFF)are used as comparative references to constitute three PEMEC cases.An advanced numerical model has been established to simulate the performance of the PEMEC using CFD software.The results show that,due to the perpendicular mainstream and the pressure difference,the JHFF enhances the mass and heat transfer inside the porous electrode by introducing strong forced convection,which promotes gas removal underneath the ribs and cooling.Compared with the comparative flow fields,the uniformities of liquid saturation,temperature,and current density distributions by using the JHFF at the anode side are increased by 19.1%,53.2%,and 40.4%,respectively.Further,mainly owing to the largest conductive area,the PEMEC with the JHFF has superior polarization performance,which is 8.05%higher than the PEMEC with the SSFF.展开更多
The production of ammonium paratungstate(APT) is riddled with the generation of wastewater,which causes environmental problems.To solve the problem of wastewater generation at source,a membrane electrolysis-NH3·H...The production of ammonium paratungstate(APT) is riddled with the generation of wastewater,which causes environmental problems.To solve the problem of wastewater generation at source,a membrane electrolysis-NH3·H2O precipitation method,which prevents wastewater generation and recycles the reagents used in the process,was proposed and investigated in this study.The electrolysis process was investigated based on parameters such as initial cathodic and anodic NaOH concentrations,and current density.The results showed that an increase in current density and initial cathodic NaOH concentration and a decrease in the initial anodic NaOH concentration would enhance the separation of tungsten and sodium.The optimum condition was found at a current density of 666 A·m^(-2),initial anodic and cathodic NaOH concentrations of 69 g·L^(-1) and 40 g·L^(-1),with a current efficiency of 75.40%,and energy consumption for producing 1 ton of NaOH was 2184 kW·h.The precipitation process was investigated based on the acidic high W/Na molar ratio solution obtained by the electrolysis process with NH3·H2O as the precipitant.Parameters such as excessive coefficient,temperature,and W/Na molar ratio were studied.The result showed that the variation of excessive coefficient and solution temperature had an opposite effect on the purity of the APT,while an increase in the W/Na molar ratio would increase the product purity.The precipitation product obtained had a purity of 99.6% and was characterized using X-ray diffraction,inductively coupled plasma,and scanning electron microscopy.The methods proposed in this study could provide fundamental information for the design of a cleaner APT production process.展开更多
Anion exchange membrane(AEM)water electrolyzers are promising energy devices for the production of clean hydrogen from seawater.However,the lack of active and robust electrocatalysts for the oxygen evolution reaction(...Anion exchange membrane(AEM)water electrolyzers are promising energy devices for the production of clean hydrogen from seawater.However,the lack of active and robust electrocatalysts for the oxygen evolution reaction(OER)severely impedes the development of this technology.In this study,a ternary layered double hydroxide(LDH)OER electrocatalyst(NiFeCo-LDH)is developed for high-performance AEM alkaline seawater electrolyzers.The AEM alkaline seawater electrolyzer catalyzed by the NiFeCo LDH shows high seawater electrolysis performance(0.84 A/cm^(2)at 1.7 Vcell)and high hydrogen production efficiency(77.6%at 0.5 A/cm^(2)),thus outperforming an electrolyzer catalyzed by a benchmark IrO_(2)electrocatalyst.The NiFeCo-LDH electrocatalyst greatly improves the kinetics of the AEM alkaline seawater electrolyzer,consequently reducing its activation loss and leading to high performance.Based on the results,this NiFeCo-LDH-catalyzed AEM alkaline seawater electrolyzer can likely surpass the energy conversion targets of the US Department of Energy.展开更多
The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for...The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.展开更多
Proton exchange membrane water electrolysis(PEMWE)plays a critical role in practical hydrogen production.Except for the electrode activities,the widespread deployment of PEMWE is severely obstructed by the poor electr...Proton exchange membrane water electrolysis(PEMWE)plays a critical role in practical hydrogen production.Except for the electrode activities,the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer(CL)and the inefficient transport structure.In this work,the PEDOT:F(Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid)ionomers with mixed proton-electron conductor(MPEC)were fabricated,which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface.The PEDOT:F exhibits strong perfluorosulfonic acid(PFSA)side chain extensibility,enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks,thus contributing to the surface reactant water adsorption.The PEMWE device employing membrane electrode assembly(MEA)prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 V under a water-splitting current of 2 A cm^(-2)(1.746 V at 2A cm^(-2) for MEA prepared by Nafion D520),along with exceptional long-term stability.Meanwhile,the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance,which is reduced by 23.4%and 17.6%at 0.1 A cm^(-2) and 1.5 A cm^(-2),respectively,as compared to the MEA prepared by D520.The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F,coupled with its remarkable structural stability.This characteristic enables expeditious mass transfer during electrolytic reactions,thereby enhancing the performance of PEMWE devices.展开更多
The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introdu...The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introduces a triple-layer Ti-PTL with a graded porous structure and a 75%ultra-high porosity backing layer,fabricated through tape casting and roll calendering.This triple-layer PTL,composed of a microporous layer,an interlayer,and a highly porous backing layer,enhances catalyst utilization,mechanical integrity,and mass transport.Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer,significantly improving oxygen evolution reaction kinetics.Numerical simulations demonstrated that the strategically designed porous structure of the triple-layer PTL facilitates efficient oxygen transport,mitigates oxygen accumulation,and improves reactant accessibility.Electrochemical evaluations showed improved performance,achieving 127 mV reduction in voltage at 2 A cm^(-2)compared to a commercial PTL,highlighting its potential to enhance PEMWE efficiency and cost-effectiveness.展开更多
Proton exchange membrane water electrolysis (PEMWE) has garnered significant attention as apivotal technology for converting surplus electricity into hydrogen for long-term storage, as well asfor providing high-purity...Proton exchange membrane water electrolysis (PEMWE) has garnered significant attention as apivotal technology for converting surplus electricity into hydrogen for long-term storage, as well asfor providing high-purity hydrogen for aerospace and high-end manufacturing applications. Withthe ongoing commercialization of PEMWE, advancing iridium-based oxygen evolution reaction(OER) catalysts remains imperative to reconcile stringent requirements for high activity, extendedlongevity, and minimized noble metal loading. The review provides a systematic analysis of theintegrated design of iridium-based catalysts in PEMWE, starting from the fundamentals of OER,including the operation environment of OER catalysts, catalytic performance evaluation withinPEMWE, as well as catalytic and dissolution mechanisms. Subsequently, the catalyst classificationand preparation/characterization techniques are summarized with the focus on the dynamic structure-property relationship. Guided by these understandings, an overview of the design strategiesfor performance enhancement is presented. Specifically, we construct a mathematical frameworkfor cost-performance optimization to offer quantitative guidance for catalyst design. Finally, futureperspectives are proposed, aiming to establish a theoretical framework for rational catalyst design.展开更多
Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct c...Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct conditions required for oxygen and hydrogen evolution reaction(OER and HER).Herein,we propose a theory-directed design of Ir-based bifunctional catalysts,Ir nanoparticles supported on mesoporous carbon spheres embedded with MoSe_(2)(Ir/MoSe_(2)@MCS),leveraging a work function(WF)-induced spontaneous built-in electric field to enhance catalytic performance.They demonstrate exceptional kinetics for both OER and HER,and potential application in the practical PEM electrolyzer,showcasing the effectiveness of this innovative approach.Low overpotentials of 252 mV for OER and 28 mV for HER to drive 10 mA cm^(-2)were observed,and the PEM electrolyzer showed the current density of 2 A cm^(-2)at 1.87 V and maintained stable activity at 1.65 V for over 30 h to deliver 1 A cm^(-2).Density functional theory calculations reveal that the WF difference at Ir/MoSe_(2)interface induces a spontaneous built-in electric field with asymmetric charge distributions,that modulate the electronic environment and d-band center of Ir promoting bifunctional active phase formation.This significantly lowers reaction barriers for water splitting by balancing intermediate adsorption,endowing the bifunctional activity.展开更多
The development of highly efficient and durable bifunctional catalysts with minimal precious metal usage is critical for advancing proton exchange membrane water electrolysis(PEMWE).We present an iridium-platinum nano...The development of highly efficient and durable bifunctional catalysts with minimal precious metal usage is critical for advancing proton exchange membrane water electrolysis(PEMWE).We present an iridium-platinum nanoalloy(IrPt)supported on lanthanum and nickel co-doped cobalt oxide,featuring a core-shell architecture with an amorphous IrPtOx shell and an IrPt core.This catalyst exhibits exceptional bifunctional activity for oxygen and hydrogen evolution reactions in acidic media,achieving 2 A cm^(-2)at 1.72 V in a PEMWE device with ultralow loadings of 0.075 mgIr cm^(-2)and 0.075 mgPt cm^(-2)at anode and cathode,respectively.It demonstrates outstanding durability,sustaining water splitting for over 646 h with a degradation rate of only 5μV h^(-1),outperforming state-of-the-art Ir-based catalysts.In situ X-ray absorption spectroscopy and density functional theory simulations reveal that the optimized charge redistribution between Ir and Pt,along with the IrPt core-IrPtOx shell structure,enhances performance.The Ir-O-Pt active sites enable a bi-nuclear mechanism for oxygen evolution reaction and a Volmer-Tafel mechanism for hydrogen evolution reaction,reducing kinetic barriers.Hierarchical porosity,abundant oxygen vacancies,and a high electrochemical surface area further improve electron and mass transfer.This work offers a cost-effective solution for green hydrogen production and advances the design of highperformance bifunctional catalysts for PEMWE.展开更多
Proton exchange membrane water electrolysis(PEMWE)technology is widely recognized as a cornerstone for green hydrogen production,offering high operational current densities exceeding 1.0 A cm^(-2),rapid dynamic respon...Proton exchange membrane water electrolysis(PEMWE)technology is widely recognized as a cornerstone for green hydrogen production,offering high operational current densities exceeding 1.0 A cm^(-2),rapid dynamic response capabilities,and zero-carbon emission characteristics[1].However,the sluggish kinetics of oxygen evolution reaction(OER)at the anode presents a critical bottleneck for large-scale commercial deployment(Fig.1(a)).Despite significant advancements through electronic structure modulation[2]and coordination environment optimization[3],the deprotonation energy barrier of oxygen-containing intermediates and the stability of active sites under acidic conditions remain unresolved challenges.展开更多
The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focus...The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.展开更多
Conventional proton exchange membrane(PEM)electrolysis technology relies on ultrapure water,as cationic impurities(such as Na^(+),Ca^(2+) and Fe^(3+))can occupy H+transport sites in the membrane[1],leading to a sharp ...Conventional proton exchange membrane(PEM)electrolysis technology relies on ultrapure water,as cationic impurities(such as Na^(+),Ca^(2+) and Fe^(3+))can occupy H+transport sites in the membrane[1],leading to a sharp rise in cathode pH,catalyst deactivation,and membrane degradation[2].This forces the system to be equipped with complex water purification equipment and even necessitates the replacement of membrane electrode assemblies(MEAs),increasing the levelized cost of hydrogen(LCOH)[3].To address this,Tao Ling's group recently proposed a"local pH regulation"strategy in Nature Energy[4].展开更多
Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been ...Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been recently achieved,which shows high activity and stability though Ir usage was reduced more than 95%than that in current commercial proton exchange membrane water electrolyzer(PEMWE).However,the activity and stability enhancement by Ir doping inγ-MnO_(2) still remains elusive.Herein,high dispersion of iridium(up to 1.37 atom%)doping in the lattice ofγ-MnO_(2) has been achieved by optimizing the thermal decomposition of the iridium precursors.Benefiting from atomic dispersive doping of Ir,the optimized Ir-MnO_(2) catalyst shows high OER activity,as it has turnover frequency of 0.655 s^(–1) at an overpotential of 300 mV in 0.5 mol L^(-1) H_(2)SO_(4).The catalyst also shows high stability,as it can sustainably work at 100 mA cm^(-2) for 24 h.Experimental and theoretical studies reveal that Ir is preferentially doped intoβphase rather than R phase,and the Ir site is the active site for OER.The OER active site is postulated to be Ir^(5+)-O(H)-Mn^(3+)unit structure on the surface.Furthermore,Ir doping changes the potential determining step from the formation of O*to the formation of*OOH,emphasizing the promoting effect toward OER derived from Ir sites.This work not only demonstrates the possibility of achieving atomic-level doping of Ir on the surface of a support to dramatically reduce Ir usage,but also,more importantly,reveals the mechanism behind accounting for the stability and activity enhancement by Ir doping.These important findings may serve as valuable guidance for further development of more efficient,stable and cost-effective low Ir-based OER catalysts for PEMWE.展开更多
Design of efficient non-precious metal electrodes for anion exchange membrane water electrolysis(AEMWE)is an ongoing challenge.We in situ constructed a CoFe layered double hydroxide nanosheet array(CoFe LDH-NS array)o...Design of efficient non-precious metal electrodes for anion exchange membrane water electrolysis(AEMWE)is an ongoing challenge.We in situ constructed a CoFe layered double hydroxide nanosheet array(CoFe LDH-NS array)on nickel foam(NF).Only 278 mV of low overpotential was required for the electrode to achieve a current density of 1000 mA·cm^(-2) for oxygen evolution reaction(OER)and stable operation for over 200 h.The high catalytic activity,mechanical stability as well as electrical conductivity could be ascribed to the intimate interfacial contact between NF substrate with NiS intermediate layer and CoFe LDH.Moreover,the unique superaerophobic surface of the NS arrays promoted the release of the bubble and the re-engagement of the electrolyte with the active sites.In situ Raman results certified that in the OER process,CoOOH was the true active phase of the catalyst.In AEMWE tests,CoFe LDH-NS arrays||Pt/C/carbon paper(CP)arrays outperformed commercial IrO_(2) at 80℃ and 1.62 V to actuate 1 A·cm^(-2) and stable operating over 1500 h.This morphology-dependent enhancement strategy may lead to new references for efficient electrode design for the next generation of AEMWE.展开更多
基金the support the National Natural Science Foundation of China(5210440)S&T Program of Hebei(23311501D)Program of HBIS Group under HG2023222。
文摘In this study,a cleaner method for separation and recovery of V/W/Na in waste selective catalytic reduction(SCR)catalyst alkaline leaching solution was proposed.The method involved membrane electrolysis followed by ion morphology pretreatme nt and solvent extraction.An acidic V(Ⅴ)/W(Ⅵ)solution was obtained using the me mbrane electrolysis method without adding any other chemical reagents.In addition,Na was recovered in the form of NaOH by product,avoiding the generation of Na containing wastewater.The electrolysis parameters were investigated,the lowest power consumption of 3063 kW·h·t^(-1)NaOH was obtained at a current density of 125 A·m^(-2)and an initial NaOH concentration of 2 mol·L^(-1).After electrolysis,oxalic acid was added to the acidic V/W containing solution,converting V(Ⅴ)negative ion to V(Ⅳ)positive ion.Since W(Ⅵ)ion state remained in negative form,the generation of heteropolyacid ions(W_(x)V_(y)O_(z)^(n-))was prevented.It was found that under the condition of oxalic acid addition/theoretical consumption 1.2 and reaction temperature 75℃,100%V(Ⅴ)was co nverted to V(Ⅳ4).Using 10%N263+10%noctanol+80%sulfonated kerosene as extractant,the highest W(Ⅵ)/V(Ⅳ)separation coefficient of 7559.76was obtained at pH=1.8,O:A ratio=1:1 and extraction time 15 min.With 2 mol·L^(-1)NaOH as stripping reagent,the W stripping efficiency reached 98.50%at O:A ratio=2:1 after 4-stages of stripping.The enrichment of V remained in the solution was realized using P204 as extractant and 20%(mass)H_(2)SO_(4)as stripping reagent.The parameters of extraction/stripping process were investigated,using 10%P204+10%TBP+80%sulfonated kerosene as extractant,the V extraction efficiency reached 97.50%at O:A ratio=1:2after 4 stages of extraction.Using 20%H_(2)SO_(4)as the stripping reagent,the V stripping efficiency was 98.30%at an O:A ratio of 4:1 after five stage s of stripping.After the entire process,a high-purity VOSO_(4)and Na_(2)WO_(4)product solutions were obtained with V/W recovery efficiency 95.84%/98.50%,separately.This study examined a more effective and cleaner method for separating V/W/Na in Na_(2)WO_(4)/NaVO_(3)solution,which may serve as a reference for the separation and recovery of V/W/Na in waste SCR catalysts.
基金financially supported by the National Natural Science Foundations of China (No.U1508217 and U1710257)the Fundamental Research Funds for the Central Universities (No.N162505002)
文摘A new method for the direct synthesis of Li2CO3 powders by membrane electrolysis from LiC1 solution is demonstrated in this paper, where a novel electrolysis system combining ventilation, agitation and loop filtration functions was reported. The aim of this work is to explore the effect of the starting concentration of LiC1 on the phase and micromorphology of Li2CO3 crystals and thereafter to explore the mechanism of crystallization and grain growth law. Scanning electron microscopy （SEM） images indicate that the particles become irregular polycrystalline from well-defined flower-like and the micro-crystals change from lamellar to needle-like and subsequently to smaller globular granules, and the surface of the crystals becomes smooth with LiC1 concentration increasing from 50 to 400 g.L^-3. The crystalline phases of the different samples were characterized using powder X-ray diffraction （XRD） and the results prove that pure LiaCO3 crystals can be obtained in a single step by the electrolysis method. The particle size distributions show that both volume mean crystal sizes and the full width at half maximum （FWHM） decrease when the starting LiC1 concentration increases from 50 to 300 g.L 3 and also decreases from 400 to 300 g-L^-3.
基金supported by the European Union and the Clean Hydrogen Joint Undertaking(Grant no.101112055).
文摘The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widespread adoption is hindered by the high cost and non-optimised design of crucial components,such as porous transport layers(PTL)and flow fields.This study comprehensively investigates the interplay between structure,mechanics,and electrochemical performance of a low-cost knitted wire mesh PTL,focusing on its potential to enhance cell assembly and operation.Electrochemical characterisation was performed on a single 4 cm^(2)cell,using 1M KOH at 60℃.Knitted wire mesh PTL,characterised by approximately 70%porosity,2mm thickness,and 1.098 tortuosity,delivered a 33%improvement in current density compared to the standard cell configuration.Introducing a knitted PTL interlayer reduced cell voltage by 74 mV at 2 A cm^(−2)by improving compression force distribution across the active area,enhancing gas transport and maintaining optimal electrical and thermal conductivity.These findings highlight the significant potential of innovative PTL designs in AEMWE to improve mechanical and operational efficiency without increasing the cost.
基金supported by the National Key Research and Development Program of China(No.2021YFA1500400)the National Natural Science Foundation of China(No.22175163)+3 种基金the Natural Science Foundation of Anhui Province(No.2208085UD04)Anhui Development and Reform Commission(Nos.AHZDCYCX-LSDT2023-08 and AHZDCYCX-LSDT2023-07)the Department of Ecology and Environment of Anhui Province(No.2023hb0018)the Fundamental Research Funds for the Central Universities(No.WK2060000016).
文摘Despite the cost and activity advantages,ruthenium-based oxygen evolution reaction(OER)catalysts face severe stability problems for proton exchange membrane water electrolysis(PEM-WE)due to Ru dissolution.Although tremendous attention has been paid to enhancing the stability and activity under small current density in three electrode systems,there still lacks validation under industrial current density at the device level.Aiming at this issue,we report highly active and durable ruthenium-iridium alloyed oxides(IrRuO_(x))as the acidic OER catalyst for PEM-WE with exceptional durability for 1600 h at an industrial current density of 2.0 A·cm^(−2).X-ray absorption spectroscopy reveals that the introduction of iridium modulates the electronic structure of Ru and strengthens the local Ru–O bonds in RuO_(2),which is crucial for ensuring activity and stability.As a result,in comparison with its RuO_(2) counterpart,IrRuO_(x) works stably against the Ru leaching-induced catalytic layer breakage during the stability test.This work demonstrates the great potential of IrRuO_(x) as the practical OER catalyst for the application in PEM-WE.
基金financial supports provided by the National Key R&D Program of China(No.2022YFB4002002)China Grinm Group Youth FundGrinm Industrial Research Institute Innovation Fund
文摘Hydrogen energy, as one of the cleanest energy sources, has emerged as a leading candidate for replacing nonrenewable energy. However, hydrogen is not directly available from nature. Challenges such as high production costs and the need for efficient large-scale production technologies remain significant obstacles. Among the various hydrogen production methods, water electrolysis stands out due to its environmentally friendly nature and the high purity of hydrogen produced. Proton exchange membrane(PEM) electrolyzers are promising devices for hydrogen production. They exhibit the superiorities in high operational current densities exceeding 2 A cm^(-2), greater resistance to fluctuations, and improved electrolysis efficiency. A critical component of PEM water electrolyzers is the porous transport layer(PTL), which serves as an electron conductor between the membrane electrode assembly and the bipolar plate, ensuring efficient mass transport between gas and liquid phases. This review provides a comprehensive examination of PTL materials,structural configurations, surface treatments, and the resulting performance of electrolytic cells. These insights aim to guide researchers in selecting appropriate PTL materials and treatments tailored to specific practical applications. Additionally, this paper analyzes operational conditions—such as compaction pressure, temperature,water flow rate, and oxygen saturation within the electrolyzer—that influence PTL performance. These factors are crucial for researchers to holistically design and optimize PEM electrolyzer systems.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51876061 and 51821004)the Fundamental Research Funds for the Central Universities (Grant No. 2018ZD04)。
文摘A three-dimensional, non-isothermal, two-phase model for a PEM water electrolysis cell(PEMEC) is established in this study.An effective connection between two-phase transport and performance in the PEMECs is built through coupling the liquid water saturation and temperature in the charge conservation equation. The distributions of liquid water and temperature with different operating(voltage, temperature, inlet velocity) and physical(contact angle, and porosity of anode gas diffusion layer) parameters are examined and discussed in detail. The results show that the water and temperature distributions, which are affected by the operating and physical parameters, have a combined effect on the cell performance. The effects of various parameters on the PEMEC are of interaction and restricted mutually. As the voltage increases, the priority factor caused by the change of inlet water velocity changes from the liquid water saturation increase to the temperature drop in the anode catalyst layer. While the priority influence factor caused by the contact angle and porosity of anode gas diffusion layer is the liquid water saturation. Decreasing the contact angle or/and increasing the porosity can improve the PEMEC performance especially at the high voltage. The results can provide a better understanding of the effect of heat and mass transfer and the foundation for optimization design.
基金supported by the National Natural Science Foundation of China(Grant Nos.51821004 and 52090062)the research project from China Three Gorges Corporation(Contract No.202003346)。
文摘The flow field structure on the bipolar plate significantly affects the performance of the proton exchange membrane electrolysis cell(PEMEC).This paper proposes a new interdigitated-jet hole flow field(JHFF)design to improve the uniformities of liquid saturation,temperature,and current density distributions.The common single-path serpentine flow field(SSFF)and interdigitated flow field(IFF)are used as comparative references to constitute three PEMEC cases.An advanced numerical model has been established to simulate the performance of the PEMEC using CFD software.The results show that,due to the perpendicular mainstream and the pressure difference,the JHFF enhances the mass and heat transfer inside the porous electrode by introducing strong forced convection,which promotes gas removal underneath the ribs and cooling.Compared with the comparative flow fields,the uniformities of liquid saturation,temperature,and current density distributions by using the JHFF at the anode side are increased by 19.1%,53.2%,and 40.4%,respectively.Further,mainly owing to the largest conductive area,the PEMEC with the JHFF has superior polarization performance,which is 8.05%higher than the PEMEC with the SSFF.
基金financially supported by National Key R&D Program of China (Nos.2020YFC1909703)the Natural Science Foundation of China (Nos.52104403)+1 种基金HBIS Group Co.,Ltd. Key R&D Program (No.20210036)Lv Liang Key R&D Program (No.2020GXZDYF7)。
文摘The production of ammonium paratungstate(APT) is riddled with the generation of wastewater,which causes environmental problems.To solve the problem of wastewater generation at source,a membrane electrolysis-NH3·H2O precipitation method,which prevents wastewater generation and recycles the reagents used in the process,was proposed and investigated in this study.The electrolysis process was investigated based on parameters such as initial cathodic and anodic NaOH concentrations,and current density.The results showed that an increase in current density and initial cathodic NaOH concentration and a decrease in the initial anodic NaOH concentration would enhance the separation of tungsten and sodium.The optimum condition was found at a current density of 666 A·m^(-2),initial anodic and cathodic NaOH concentrations of 69 g·L^(-1) and 40 g·L^(-1),with a current efficiency of 75.40%,and energy consumption for producing 1 ton of NaOH was 2184 kW·h.The precipitation process was investigated based on the acidic high W/Na molar ratio solution obtained by the electrolysis process with NH3·H2O as the precipitant.Parameters such as excessive coefficient,temperature,and W/Na molar ratio were studied.The result showed that the variation of excessive coefficient and solution temperature had an opposite effect on the purity of the APT,while an increase in the W/Na molar ratio would increase the product purity.The precipitation product obtained had a purity of 99.6% and was characterized using X-ray diffraction,inductively coupled plasma,and scanning electron microscopy.The methods proposed in this study could provide fundamental information for the design of a cleaner APT production process.
基金supported by the Fundamental Research Program of the Korean Institute of Materials Science(PNK7550)the National Research Council of Science&Technology(NST)grant by the MSIT(CAP21000-000)the New&Renewable Energy Core Technology Program of the KETEP(20213030040520)in the Republic of Korea。
文摘Anion exchange membrane(AEM)water electrolyzers are promising energy devices for the production of clean hydrogen from seawater.However,the lack of active and robust electrocatalysts for the oxygen evolution reaction(OER)severely impedes the development of this technology.In this study,a ternary layered double hydroxide(LDH)OER electrocatalyst(NiFeCo-LDH)is developed for high-performance AEM alkaline seawater electrolyzers.The AEM alkaline seawater electrolyzer catalyzed by the NiFeCo LDH shows high seawater electrolysis performance(0.84 A/cm^(2)at 1.7 Vcell)and high hydrogen production efficiency(77.6%at 0.5 A/cm^(2)),thus outperforming an electrolyzer catalyzed by a benchmark IrO_(2)electrocatalyst.The NiFeCo-LDH electrocatalyst greatly improves the kinetics of the AEM alkaline seawater electrolyzer,consequently reducing its activation loss and leading to high performance.Based on the results,this NiFeCo-LDH-catalyzed AEM alkaline seawater electrolyzer can likely surpass the energy conversion targets of the US Department of Energy.
基金National Natural Science Foundation of China(No.52476192,No.52106237)Natural Science Foundation of Heilongjiang Province(No.YQ2022E027)。
文摘The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.
基金supported by the National Natural Science Foundation of China(52202009)Key Research and Development Program of Guangdong Province(2020B0909040001)+1 种基金Key R&D project of Hubei Province,China(2021AAA006)Guangdong Hydrogen Energy Institute of WHUT under Guangdong Key Areas Research and Development Program(2019B090909003).
文摘Proton exchange membrane water electrolysis(PEMWE)plays a critical role in practical hydrogen production.Except for the electrode activities,the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer(CL)and the inefficient transport structure.In this work,the PEDOT:F(Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid)ionomers with mixed proton-electron conductor(MPEC)were fabricated,which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface.The PEDOT:F exhibits strong perfluorosulfonic acid(PFSA)side chain extensibility,enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks,thus contributing to the surface reactant water adsorption.The PEMWE device employing membrane electrode assembly(MEA)prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 V under a water-splitting current of 2 A cm^(-2)(1.746 V at 2A cm^(-2) for MEA prepared by Nafion D520),along with exceptional long-term stability.Meanwhile,the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance,which is reduced by 23.4%and 17.6%at 0.1 A cm^(-2) and 1.5 A cm^(-2),respectively,as compared to the MEA prepared by D520.The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F,coupled with its remarkable structural stability.This characteristic enables expeditious mass transfer during electrolytic reactions,thereby enhancing the performance of PEMWE devices.
基金supported by the collaborative research project of Hyundai Motor Company.Also,this work was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00406086,RS-2024-00338569,and RS-2024-00467191)。
文摘The commercialization of proton exchange membrane water electrolysis(PEMWE)for green hydrogen production hinges on the development of low-cost,high-performance titanium porous transport layers(PTLs).This study introduces a triple-layer Ti-PTL with a graded porous structure and a 75%ultra-high porosity backing layer,fabricated through tape casting and roll calendering.This triple-layer PTL,composed of a microporous layer,an interlayer,and a highly porous backing layer,enhances catalyst utilization,mechanical integrity,and mass transport.Digital twin technology using X-ray revealed increased contact area and triple-phase boundary at the interface with the catalyst layer,significantly improving oxygen evolution reaction kinetics.Numerical simulations demonstrated that the strategically designed porous structure of the triple-layer PTL facilitates efficient oxygen transport,mitigates oxygen accumulation,and improves reactant accessibility.Electrochemical evaluations showed improved performance,achieving 127 mV reduction in voltage at 2 A cm^(-2)compared to a commercial PTL,highlighting its potential to enhance PEMWE efficiency and cost-effectiveness.
文摘Proton exchange membrane water electrolysis (PEMWE) has garnered significant attention as apivotal technology for converting surplus electricity into hydrogen for long-term storage, as well asfor providing high-purity hydrogen for aerospace and high-end manufacturing applications. Withthe ongoing commercialization of PEMWE, advancing iridium-based oxygen evolution reaction(OER) catalysts remains imperative to reconcile stringent requirements for high activity, extendedlongevity, and minimized noble metal loading. The review provides a systematic analysis of theintegrated design of iridium-based catalysts in PEMWE, starting from the fundamentals of OER,including the operation environment of OER catalysts, catalytic performance evaluation withinPEMWE, as well as catalytic and dissolution mechanisms. Subsequently, the catalyst classificationand preparation/characterization techniques are summarized with the focus on the dynamic structure-property relationship. Guided by these understandings, an overview of the design strategiesfor performance enhancement is presented. Specifically, we construct a mathematical frameworkfor cost-performance optimization to offer quantitative guidance for catalyst design. Finally, futureperspectives are proposed, aiming to establish a theoretical framework for rational catalyst design.
文摘Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct conditions required for oxygen and hydrogen evolution reaction(OER and HER).Herein,we propose a theory-directed design of Ir-based bifunctional catalysts,Ir nanoparticles supported on mesoporous carbon spheres embedded with MoSe_(2)(Ir/MoSe_(2)@MCS),leveraging a work function(WF)-induced spontaneous built-in electric field to enhance catalytic performance.They demonstrate exceptional kinetics for both OER and HER,and potential application in the practical PEM electrolyzer,showcasing the effectiveness of this innovative approach.Low overpotentials of 252 mV for OER and 28 mV for HER to drive 10 mA cm^(-2)were observed,and the PEM electrolyzer showed the current density of 2 A cm^(-2)at 1.87 V and maintained stable activity at 1.65 V for over 30 h to deliver 1 A cm^(-2).Density functional theory calculations reveal that the WF difference at Ir/MoSe_(2)interface induces a spontaneous built-in electric field with asymmetric charge distributions,that modulate the electronic environment and d-band center of Ir promoting bifunctional active phase formation.This significantly lowers reaction barriers for water splitting by balancing intermediate adsorption,endowing the bifunctional activity.
基金supported by overseas Outstanding Youth Science Fund Project provided by National Natural Science Foundation of China(NSFC)under contract No.22Z990204807Natural Sciences—Basic Research Special Zone Program provided by shanghai government under contract No.22Z511203738+3 种基金Key Open Fund Project provided by Shaoxing New Energy and Molecular Engineering Research Institute,Shanghai Jiao Tong University under contract No.22H010103236Sinopec Natural Science research project provided by Sinopec research institute of petroleum processing under contract No.23H010100026support from National Science Foundation of China(22309113)Scientific and Technological Project of Yunnan Precious Metals Laboratory(YPML20240502029).
文摘The development of highly efficient and durable bifunctional catalysts with minimal precious metal usage is critical for advancing proton exchange membrane water electrolysis(PEMWE).We present an iridium-platinum nanoalloy(IrPt)supported on lanthanum and nickel co-doped cobalt oxide,featuring a core-shell architecture with an amorphous IrPtOx shell and an IrPt core.This catalyst exhibits exceptional bifunctional activity for oxygen and hydrogen evolution reactions in acidic media,achieving 2 A cm^(-2)at 1.72 V in a PEMWE device with ultralow loadings of 0.075 mgIr cm^(-2)and 0.075 mgPt cm^(-2)at anode and cathode,respectively.It demonstrates outstanding durability,sustaining water splitting for over 646 h with a degradation rate of only 5μV h^(-1),outperforming state-of-the-art Ir-based catalysts.In situ X-ray absorption spectroscopy and density functional theory simulations reveal that the optimized charge redistribution between Ir and Pt,along with the IrPt core-IrPtOx shell structure,enhances performance.The Ir-O-Pt active sites enable a bi-nuclear mechanism for oxygen evolution reaction and a Volmer-Tafel mechanism for hydrogen evolution reaction,reducing kinetic barriers.Hierarchical porosity,abundant oxygen vacancies,and a high electrochemical surface area further improve electron and mass transfer.This work offers a cost-effective solution for green hydrogen production and advances the design of highperformance bifunctional catalysts for PEMWE.
基金financially supported by the Natural Science Foundation of Hunan Province(2023JJ40608,2024JJ6413)the Majoy Project of the Education Department of Hunan Province(24A0610).
文摘Proton exchange membrane water electrolysis(PEMWE)technology is widely recognized as a cornerstone for green hydrogen production,offering high operational current densities exceeding 1.0 A cm^(-2),rapid dynamic response capabilities,and zero-carbon emission characteristics[1].However,the sluggish kinetics of oxygen evolution reaction(OER)at the anode presents a critical bottleneck for large-scale commercial deployment(Fig.1(a)).Despite significant advancements through electronic structure modulation[2]and coordination environment optimization[3],the deprotonation energy barrier of oxygen-containing intermediates and the stability of active sites under acidic conditions remain unresolved challenges.
文摘The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.
基金the Natural Science Foundation of Guangxi,China(No.2021GXNSFBA220058)the National Natural Science Foundation of China(Nos.22272036, 22362008)Guangxi Normal University Research Grant,China(No.2022TD).
文摘Conventional proton exchange membrane(PEM)electrolysis technology relies on ultrapure water,as cationic impurities(such as Na^(+),Ca^(2+) and Fe^(3+))can occupy H+transport sites in the membrane[1],leading to a sharp rise in cathode pH,catalyst deactivation,and membrane degradation[2].This forces the system to be equipped with complex water purification equipment and even necessitates the replacement of membrane electrode assemblies(MEAs),increasing the levelized cost of hydrogen(LCOH)[3].To address this,Tao Ling's group recently proposed a"local pH regulation"strategy in Nature Energy[4].
文摘Construction of iridium(Ir)based active sites on certain acid stable supports now is a general strategy for the development of low-Ir OER catalysts.Atomically doped Ir in the lattice of acid stableγ-MnO_(2) has been recently achieved,which shows high activity and stability though Ir usage was reduced more than 95%than that in current commercial proton exchange membrane water electrolyzer(PEMWE).However,the activity and stability enhancement by Ir doping inγ-MnO_(2) still remains elusive.Herein,high dispersion of iridium(up to 1.37 atom%)doping in the lattice ofγ-MnO_(2) has been achieved by optimizing the thermal decomposition of the iridium precursors.Benefiting from atomic dispersive doping of Ir,the optimized Ir-MnO_(2) catalyst shows high OER activity,as it has turnover frequency of 0.655 s^(–1) at an overpotential of 300 mV in 0.5 mol L^(-1) H_(2)SO_(4).The catalyst also shows high stability,as it can sustainably work at 100 mA cm^(-2) for 24 h.Experimental and theoretical studies reveal that Ir is preferentially doped intoβphase rather than R phase,and the Ir site is the active site for OER.The OER active site is postulated to be Ir^(5+)-O(H)-Mn^(3+)unit structure on the surface.Furthermore,Ir doping changes the potential determining step from the formation of O*to the formation of*OOH,emphasizing the promoting effect toward OER derived from Ir sites.This work not only demonstrates the possibility of achieving atomic-level doping of Ir on the surface of a support to dramatically reduce Ir usage,but also,more importantly,reveals the mechanism behind accounting for the stability and activity enhancement by Ir doping.These important findings may serve as valuable guidance for further development of more efficient,stable and cost-effective low Ir-based OER catalysts for PEMWE.
基金supported by the National Natural Science Foundation of China(No.22272198)the Innovative Talent Program of Karamay(No.20222023hjcxrc0011)+2 种基金the Fundamental Research Funds of Xinjiang Uygur Autonomous Region(No.XJEDU2023P169)Xinjiang Tianshan Innovation Team program(No.2024D14004)the National Key Research and Development Program of China(No.2023YFB4004702).
文摘Design of efficient non-precious metal electrodes for anion exchange membrane water electrolysis(AEMWE)is an ongoing challenge.We in situ constructed a CoFe layered double hydroxide nanosheet array(CoFe LDH-NS array)on nickel foam(NF).Only 278 mV of low overpotential was required for the electrode to achieve a current density of 1000 mA·cm^(-2) for oxygen evolution reaction(OER)and stable operation for over 200 h.The high catalytic activity,mechanical stability as well as electrical conductivity could be ascribed to the intimate interfacial contact between NF substrate with NiS intermediate layer and CoFe LDH.Moreover,the unique superaerophobic surface of the NS arrays promoted the release of the bubble and the re-engagement of the electrolyte with the active sites.In situ Raman results certified that in the OER process,CoOOH was the true active phase of the catalyst.In AEMWE tests,CoFe LDH-NS arrays||Pt/C/carbon paper(CP)arrays outperformed commercial IrO_(2) at 80℃ and 1.62 V to actuate 1 A·cm^(-2) and stable operating over 1500 h.This morphology-dependent enhancement strategy may lead to new references for efficient electrode design for the next generation of AEMWE.
