In co-ionic conducting solid oxide fuel cell （SOFC）, both oxygen ion （O2） and proton （H＋） can transport through the electrolyte, generating steam in both the an-ode and cathode. Thus the mass transport phenomen...In co-ionic conducting solid oxide fuel cell （SOFC）, both oxygen ion （O2） and proton （H＋） can transport through the electrolyte, generating steam in both the an-ode and cathode. Thus the mass transport phenomenon in the electrodes is quite different from that in conventional SOFC with oxygen ion conducting electrolyte （O-SOFC） or with proton conducting electrolyte （H-SOFC）. The generation of steam in both electrodes also affects the concentration over-potential loss and further the SOFC performance. However, no detailed modeling study on SOFCs with co-ionic electrolyte has been reported yet. In this paper, a new mathematical model for SOFC based on co-ionic electrolyte was developed to predict its actual performance considering three major kinds of overpotentials. Ohm＇s law and the Butler-Volmer formula were used to model the ion conduction and electrochemical reactions, respectively. The dusty gas model （DGM） was employed to simulate the mass transport processes in the porous electrodes. Parametric simulations were performed to investigate the effects of proton transfer number （tH） and current density （jtotal） on the cell performance. It is interesting to find that the co-ionic conducting SOFC could perform better than O-SOFC and H-SOFC by choosing an appropriate proton transfer number. In addition, the co-ionic SOFC shows smaller difference between the anode and cathode concentration overpotentials than O-SOFC and H-SOFC at certain t H values. The results could help material selection for enhancing SOFC performance.展开更多
Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7...Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.展开更多
Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene...Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene and metal compounds has been constructed via a controllable strategy.For demonstration,a 3D MXene framework with anchored heterostructure CoNi/CoNiP and nitrogen-doped carbon(NC)called H-CNP@M is constructed by metal-ion inducement and phosphorization.The bimetal-semiconductor heterostructure greatly enhances the catalytic performance.The H-CNP@M exhibits superior activities to-Ward ORR(E_(i/2)=0.833V)and OER(η_(10)=294 mV).Both aqueous and all-solid-state ZAB assembled with H-CNP@M demonstrate superior performance(peak power density of 166.5 mW/cm^(2)in aqueous case).This work provides a facile and general strategy to prepare MXene-supported bimetallic heterostructure for high-performance electrochemical energy devices.展开更多
Carboxylesterase,a necessary enzyme in various mammalian cells,has been employed in various biological applications.Herein,we designed and synthesized a novel carboxylesterase-based prodrug,which can realize simultane...Carboxylesterase,a necessary enzyme in various mammalian cells,has been employed in various biological applications.Herein,we designed and synthesized a novel carboxylesterase-based prodrug,which can realize simultaneous drug-release imaging and cancer chemotherapy.This prodrug comprises three parts：coumarin as the fluorophore and the cleavable architecture,chlorambucil as the anticancer drug,and acetyl group as the enzyme-responsive unit.The presence of carboxylesterase leads to the activation of coumarin fluorescence,and this fluorescence serves as the reporting signal for assessing the enzyme level and drug release.Moreover,the prodrug was incorporated in liposome for monitoring drug release and chemotherapeutic effect in living cells.Upon internalization by HeLa cells,the prodrug can release chlorambucil and exhibit high cytotoxicity.This approach may provide some helpful insights for enhancing therapeutic effect and tracking the release of prodrug.展开更多
Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research...Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research on design and fabrication of precious-metal-free catalytic materials for overall water electrolysis in non-alkaline environment,especially highlighting several optimizing approaches to enhance the catalytic behavior and to realize effective bifunctional electrocatalysts.All these involved noble-metal-free electrocatalysts are classified into transition-metal oxides(TMOs),transition-metal nitrides(TMNs),transition-metal carbides(TMCs),transition-metal phosphides(TMPs),transition-metal chalcogenides,metal complexes,and metal-free carbons,as shown in the main part.Besides,the paper also offers an introduction of the fundamental electrochemistry of water splitting before entering the subject,as well as a prospective discussion on mechanism understanding,novel catalysts fabrication,and standardized performance measurements/evaluation in the last section.展开更多
Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current stud...Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current studies have come across many challenges,e.g.serious capacity degradation and inferior rate capability caused by severe structural collapse and sluggish reaction kinetics,highlighting the need for further improvement in efficient utilization of the layered space.Herein,this study employs a novel crystal orientation regulation to enhance the performance of BiOBr electrode by a facile solvothermal method to efficiently utilize the interlayered structu re.The delicate design of BiOBr(BOB)succeeds in maximizing the exposed(110)crystalline plane,providing efficient pathways for ion diffusion and streamlining the mass migration process.Moreover,the optimized band structure and the formation of oxygen vacancies in this designed material have been found,enabling high electrical conductivity,accelerating the charge transfer process and facilitating rapid reaction rate.Owing to the simultaneously enhanced mass transfer at the interlayers and the charge transfer during the phase conversion process,the BOB-110 electrode exhibits exceptional electrochemical performances,boasting impressive charge storage and rate capability(159 mAh g^(-1)at 4 A g^(-1)),and outstanding cycling stability of capacity retention around 75%(119 mAh g^(-1))even after 1000 cycles at a high current density of 4 A g^(-1).These findings underscore the substantial potential of BiOBr electrodes for future energy storage devices such as wearable electronics and power grids where the power output,lifespan,and affordability are simultaneously required.展开更多
Rational construction of carbon-based materials with high-efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn-air batteries(ZABs)yet ...Rational construction of carbon-based materials with high-efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn-air batteries(ZABs)yet it still remains challenging.Herein,this study employs a simple mixing-calcination strategy to fabricate a high-performance bifunctional composite catalyst composed of N-doped graphitic carbon encapsulating Co nanoparticles(Co@NrC).Benefiting from the core-shell architectural and compositional advantages of favorable electronic configuration,more exposed active sites,sufficient electric conductivity,rich defects,and excellent charge transport,the optimal Co@NrC hybrid(Co@NrC-0.3)presents outstanding catalytic activity and stability toward oxygen-related electrochemical reactions(oxygen reduction and evolution reactions,i.e.,ORR and OER),with a low potential gap of 0.766 V.Besides,the rechargeable liquid ZAB assembled with this hybrid electrocatalyst delivers a high peak power density of 168 mW cm^(−2),a small initial discharge-charge potential gap of 0.45 V at 10 mA cm^(−2),and a good rate performance.Furthermore,a relatively large power density of 108 mW cm^(−2) is also obtained with the Co@NrC-0.3-based flexible solid-state ZAB,which can well power LED lights.Such work offers insights in developing excellent bifunctional electrocatalysts for both OER and ORR and highlights their potential applications in metal-air batteries and other energy-conversion/storage devices.展开更多
The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of cruc...The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of crucial importance for the rational design of flexible rechargeable Zn-air batteries(ZABs).Considering their good elasticity,high conductivity,and superior thermal and chemical stability,carbon nanotubes have been widely used as a catalyst support in various electrocatalysts,while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials.Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long-term operating stability,in particular in flexible devices,pure carbon electrocatalyst is highly appreciated.Herein,a free-standing air electrode with cobalt nanoparticles encapsulated N-codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two-step in situ growth method.Such a carbon-based electrode shows outstanding activity for both ORR and OER.The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions.Moreover,the polarization and round-trip efficiency for the flexible battery is 0.67 V and 64.4%at 2 mA/cm2,respectively,even after being operated for 30 hours.This study provides a feasible way to design all carbon-based free-standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.展开更多
基金supported by Research Grant Council (RGC) of Hong Kong (PolyU 5238/11E)
文摘In co-ionic conducting solid oxide fuel cell （SOFC）, both oxygen ion （O2） and proton （H＋） can transport through the electrolyte, generating steam in both the an-ode and cathode. Thus the mass transport phenomenon in the electrodes is quite different from that in conventional SOFC with oxygen ion conducting electrolyte （O-SOFC） or with proton conducting electrolyte （H-SOFC）. The generation of steam in both electrodes also affects the concentration over-potential loss and further the SOFC performance. However, no detailed modeling study on SOFCs with co-ionic electrolyte has been reported yet. In this paper, a new mathematical model for SOFC based on co-ionic electrolyte was developed to predict its actual performance considering three major kinds of overpotentials. Ohm＇s law and the Butler-Volmer formula were used to model the ion conduction and electrochemical reactions, respectively. The dusty gas model （DGM） was employed to simulate the mass transport processes in the porous electrodes. Parametric simulations were performed to investigate the effects of proton transfer number （tH） and current density （jtotal） on the cell performance. It is interesting to find that the co-ionic conducting SOFC could perform better than O-SOFC and H-SOFC by choosing an appropriate proton transfer number. In addition, the co-ionic SOFC shows smaller difference between the anode and cathode concentration overpotentials than O-SOFC and H-SOFC at certain t H values. The results could help material selection for enhancing SOFC performance.
基金supported by the Research Grants Council,University Grants Committee,Hong Kong SAR(Project Number:N_PolyU552/20)supported by the National Nature Science Foundation of China(22209138)Guangdong Basic and Applied Basic Research Foundation(2021A1515110464).
文摘Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.
基金supported by Natural Science Foundation of Jiangsu Province(No.BK20200406)National Natural Science Foundation of China(Nos.51731004,22075263,52002366)+2 种基金National Key R&D Program of China(No.2021YFA1501502)the Fundamental Research Funds for the Central Universities(No.WK2060000039)the Collaborative Research Fund(No.C5031-20G)from Research Grant Council,University Grants Committee,Hong Kong SAR,and Project of Strategic Importance Program of The Hong Kong Polytechnic University(No.P0035168).
文摘Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene and metal compounds has been constructed via a controllable strategy.For demonstration,a 3D MXene framework with anchored heterostructure CoNi/CoNiP and nitrogen-doped carbon(NC)called H-CNP@M is constructed by metal-ion inducement and phosphorization.The bimetal-semiconductor heterostructure greatly enhances the catalytic performance.The H-CNP@M exhibits superior activities to-Ward ORR(E_(i/2)=0.833V)and OER(η_(10)=294 mV).Both aqueous and all-solid-state ZAB assembled with H-CNP@M demonstrate superior performance(peak power density of 166.5 mW/cm^(2)in aqueous case).This work provides a facile and general strategy to prepare MXene-supported bimetallic heterostructure for high-performance electrochemical energy devices.
基金financial support by the Science and Technology Planning Project of Guangzhou(No.201607020015)the Science and Technology Planning Project of Guangdong Province(No.2014A010105009)
文摘Carboxylesterase,a necessary enzyme in various mammalian cells,has been employed in various biological applications.Herein,we designed and synthesized a novel carboxylesterase-based prodrug,which can realize simultaneous drug-release imaging and cancer chemotherapy.This prodrug comprises three parts：coumarin as the fluorophore and the cleavable architecture,chlorambucil as the anticancer drug,and acetyl group as the enzyme-responsive unit.The presence of carboxylesterase leads to the activation of coumarin fluorescence,and this fluorescence serves as the reporting signal for assessing the enzyme level and drug release.Moreover,the prodrug was incorporated in liposome for monitoring drug release and chemotherapeutic effect in living cells.Upon internalization by HeLa cells,the prodrug can release chlorambucil and exhibit high cytotoxicity.This approach may provide some helpful insights for enhancing therapeutic effect and tracking the release of prodrug.
基金M.Ni thanks the funding support(Project Number:PolyU 152214/17E and PolyU 152064/18E)from Research Grant Council,University Grants Committee,Hong Kong SAR。
文摘Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research on design and fabrication of precious-metal-free catalytic materials for overall water electrolysis in non-alkaline environment,especially highlighting several optimizing approaches to enhance the catalytic behavior and to realize effective bifunctional electrocatalysts.All these involved noble-metal-free electrocatalysts are classified into transition-metal oxides(TMOs),transition-metal nitrides(TMNs),transition-metal carbides(TMCs),transition-metal phosphides(TMPs),transition-metal chalcogenides,metal complexes,and metal-free carbons,as shown in the main part.Besides,the paper also offers an introduction of the fundamental electrochemistry of water splitting before entering the subject,as well as a prospective discussion on mechanism understanding,novel catalysts fabrication,and standardized performance measurements/evaluation in the last section.
基金supported by the CRF grant of the Hong Kong Research Grant Council(C5031-20G)the Guang Dong Basic and Applied Basic Research Foundation(2024A1515013283)the Seed Fund of University Research Committee(2201100760)。
文摘Bismuth oxybromide(BiOBr)is being actively researched as a promising anode material for aqueous batteries due to its unique layered structure,which theoretically allows for efficient ion diffusion.However,current studies have come across many challenges,e.g.serious capacity degradation and inferior rate capability caused by severe structural collapse and sluggish reaction kinetics,highlighting the need for further improvement in efficient utilization of the layered space.Herein,this study employs a novel crystal orientation regulation to enhance the performance of BiOBr electrode by a facile solvothermal method to efficiently utilize the interlayered structu re.The delicate design of BiOBr(BOB)succeeds in maximizing the exposed(110)crystalline plane,providing efficient pathways for ion diffusion and streamlining the mass migration process.Moreover,the optimized band structure and the formation of oxygen vacancies in this designed material have been found,enabling high electrical conductivity,accelerating the charge transfer process and facilitating rapid reaction rate.Owing to the simultaneously enhanced mass transfer at the interlayers and the charge transfer during the phase conversion process,the BOB-110 electrode exhibits exceptional electrochemical performances,boasting impressive charge storage and rate capability(159 mAh g^(-1)at 4 A g^(-1)),and outstanding cycling stability of capacity retention around 75%(119 mAh g^(-1))even after 1000 cycles at a high current density of 4 A g^(-1).These findings underscore the substantial potential of BiOBr electrodes for future energy storage devices such as wearable electronics and power grids where the power output,lifespan,and affordability are simultaneously required.
基金the Theme-based Scheme(project number:T23-601/17-R)from Research Grant Council,University Grants Committee,Hong Kong SAR,China.
文摘Rational construction of carbon-based materials with high-efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn-air batteries(ZABs)yet it still remains challenging.Herein,this study employs a simple mixing-calcination strategy to fabricate a high-performance bifunctional composite catalyst composed of N-doped graphitic carbon encapsulating Co nanoparticles(Co@NrC).Benefiting from the core-shell architectural and compositional advantages of favorable electronic configuration,more exposed active sites,sufficient electric conductivity,rich defects,and excellent charge transport,the optimal Co@NrC hybrid(Co@NrC-0.3)presents outstanding catalytic activity and stability toward oxygen-related electrochemical reactions(oxygen reduction and evolution reactions,i.e.,ORR and OER),with a low potential gap of 0.766 V.Besides,the rechargeable liquid ZAB assembled with this hybrid electrocatalyst delivers a high peak power density of 168 mW cm^(−2),a small initial discharge-charge potential gap of 0.45 V at 10 mA cm^(−2),and a good rate performance.Furthermore,a relatively large power density of 108 mW cm^(−2) is also obtained with the Co@NrC-0.3-based flexible solid-state ZAB,which can well power LED lights.Such work offers insights in developing excellent bifunctional electrocatalysts for both OER and ORR and highlights their potential applications in metal-air batteries and other energy-conversion/storage devices.
基金Zongping Shao and Kaiming Liao thank the funding support provide by the National Key R&D Program of China(Grant no.2018YFB0905400)Kaiming Liao thanks the funding support provided by the National Natural Science Foundation of China(Grant no.51802152)the Natural Science Foundation of Jiangsu Province of China(Grant no.BK20170974).A Project Funded by Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of crucial importance for the rational design of flexible rechargeable Zn-air batteries(ZABs).Considering their good elasticity,high conductivity,and superior thermal and chemical stability,carbon nanotubes have been widely used as a catalyst support in various electrocatalysts,while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials.Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long-term operating stability,in particular in flexible devices,pure carbon electrocatalyst is highly appreciated.Herein,a free-standing air electrode with cobalt nanoparticles encapsulated N-codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two-step in situ growth method.Such a carbon-based electrode shows outstanding activity for both ORR and OER.The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions.Moreover,the polarization and round-trip efficiency for the flexible battery is 0.67 V and 64.4%at 2 mA/cm2,respectively,even after being operated for 30 hours.This study provides a feasible way to design all carbon-based free-standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.
