The development of non-platinum group metal(non-PGM)and efficient multifunctional electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and hydrogen evolution reaction(HER)with high activi...The development of non-platinum group metal(non-PGM)and efficient multifunctional electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and hydrogen evolution reaction(HER)with high activity and stability remains a great challenge.Herein,by in-situ transforming silver manganese composite oxide heterointerface into boosted Mott-Schottky heterointerface through a facile carbon reduction strategy,a nanorod-like silver/manganese oxide with superior multifunctional catalytic activities for ORR,OER and HER and stability was obtained.The nanorod-like silver/manganese oxide with Mott-Schottky heterointerface(designated as Ag/Mn_(3)O_(4))exhibits an ORR half-wave potential of 0.831 V(vs.RHE)in 0.1 M KOH,an OER overpotential of 338 mV and a HER overpotential of 177 mV at the current density of 10 mA·cm^(-2)in 1 M KOH,contributing to its noble-metal benchmarks comparable performance in aqueous aluminum-air(Al-air)battery and laboratorial overall water splitting electrolytic cell.Moreover,in-situ electrochemical Raman and synchrotron radiation spectroscopic measurements were conducted to further illustrate the catalytic mechanism of Ag/Mn_(3)O_(4)Mott-Schottky heterointerface towards various electrocatalytic reactions.At the heterointerface,the Ag phase serves as the electron donor and the active phase for ORR and HER,while the Mn_(3)O_(4)phase serves as the electron acceptor and the active phase for OER,respectively.This work deepens the understanding of the Mott-Schottky effect on electrocatalysis and fills in the gap in fundamental physical principles that are behind measured electrocatalytic activity,which offers substantial implications for the rational design of cost-effective multifunctional electrocatalysts with Mott-Schottky effect.展开更多
LaMnO3 catalysts with three-dimensionally ordered holes perovskite structure were prepared via closepacked SiO2 template synthesized by Stober-Frink method. SEM, XRD and BET were employed to characterize the microstru...LaMnO3 catalysts with three-dimensionally ordered holes perovskite structure were prepared via closepacked SiO2 template synthesized by Stober-Frink method. SEM, XRD and BET were employed to characterize the microstructure, phases and specific surface area. CV method was used to the oxygen electrode beha-vior of catalysts. Diameter of the holes was about 330 nm, corresponding to the size of SiO2 template. Full-cell discharge tests were performed on aluminum-air battery fabricated by porous LaMnO3.Results showed that the discharge performance of porous LaMnO3 were 1.54 V, 1.42 V and 1.24 V respectively when the discharge currents were set at 5 mA/cm^2,10 mA/cm^2 and 20 mA/cm^2, respectively, which were higher than that of LaMnO3 prepared by coprecipitation method（1.33 V, 1.09 V, 0.63 V, respectively）.展开更多
Conventional Al-air battery has many disadvantages for miniwatt applications,such as the complex water management,bulky electrolyte storage and potential leakage hazard.Moreover,the self-corrosion of Al anode continue...Conventional Al-air battery has many disadvantages for miniwatt applications,such as the complex water management,bulky electrolyte storage and potential leakage hazard.Moreover,the self-corrosion of Al anode continues even when the electrolyte flow is stopped,leading to great Al waste.To tackle these issues,an innovative cotton-based aluminum-air battery is developed in this study.Instead of flowing alkaline solution,cotton substrate pre-deposited with solid alkaline is used,together with a small water reservoir to continuously wet the cotton and dissolve the alkaline in-situ.In this manner,the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir,while the thick aluminum anode can be reused for tens of times until complete consumption.The cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte,leading to a high peak power density of 73 mW cm^(-2) and a high specific energy of 930 mW h g^(-1).Moreover,the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline,so that it can be precisely controlled according to the mission profile to avoid Al waste.Finally,a two-cell battery pack with common water reservoir is developed,which can provide a voltage of 2.7 V and a power output of 223.8 mW.With further scaling-up and stacking,this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.展开更多
The effects of 0.01 wt.%Ga on microstructure and electrochemical performance of Al−0.4Mg−0.05Sn−0.03Hg anodes in NaOH solutions were investigated.Potentiodynamic polarization,electrochemical impedance spectroscopy,and...The effects of 0.01 wt.%Ga on microstructure and electrochemical performance of Al−0.4Mg−0.05Sn−0.03Hg anodes in NaOH solutions were investigated.Potentiodynamic polarization,electrochemical impedance spectroscopy,and galvanostatic discharge tests were used to assess the electrochemical performance of the Al−Mg−Sn−Hg−Ga anodes.The results show that the addition of 0.01 wt.%Ga in Al−0.4Mg−0.05Sn−0.03Hg anode enhances its corrosion resistance and discharge activity.It is benefited from the refined second phases and homogenous microstructure of Al−Mg−Sn−Hg−Ga anode,which restrains the local crystallographic corrosion and chunk effect.Compared with Al−Mg−Sn−Hg anode,the corrosion current density and the mass loss rate of Al−Mg−Sn−Hg−Ga anode decrease by 57%and 93%,respectively.When discharging at the current density of 20 mA/cm^(2),the discharge voltage,current efficiency and specific capacity of the single Al−air battery with Al−0.4Mg−0.05Sn−0.03Hg−0.01Ga anode are 1.46 V,33.1%,and 1019.2 A·h·kg^(−1),respectively.The activation mechanism of Ga on Al−Mg−Sn−Hg−Ga anode materials was also discussed.展开更多
Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue...Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), respectively.By studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.展开更多
Developing large-scale and highly efficient oxygen reduction reaction(ORR)catalysts acts a vital role in realizing wide application of metal–air batteries.Here,we propose a gas-foaming strategy to fabricate sustainab...Developing large-scale and highly efficient oxygen reduction reaction(ORR)catalysts acts a vital role in realizing wide application of metal–air batteries.Here,we propose a gas-foaming strategy to fabricate sustainable and 3D hierarchically porous N-doped carbon with high specific surface area and abundant defects sites derived from biomass.The obtained catalyst exhibits prominent ORR property with higher half-wave potential(0.861 V)and slightly lower kinetic current density(32.44 m A cm^-2),compared to Pt/C(0.856 V and 43.61 m A cm^-1).Furthermore,employing it as catalyst of air cathode,the Al–air battery delivers remarkable discharge performance with excellent power density of 401 m W cm^-2,distinguished energy density of 2453.4 Wh kg^-1 and extremely high open-circuit voltage of 1.85 V among the reported metal–air batteries in the literatures.This gas-foaming strategy for full utilization of biomass affords a chance to explore scalable advanced catalysts in metal–air battery.展开更多
Aluminum-air(Al-air) batteries are promising candidates for energy storage applications because of their high theoretical energy density and low cost.Nevertheless,their developments have been severely hindered by mult...Aluminum-air(Al-air) batteries are promising candidates for energy storage applications because of their high theoretical energy density and low cost.Nevertheless,their developments have been severely hindered by multiple obstacles,among which the activation and self-corrosion inhibition of Al anode have been considered to be significant challenges.In neutral electrolytes,the main problem is the activation of Al anode,while the self-corrosion of Al anode becomes dominant in alkaline electrolytes.Considerable efforts have been devoted to overcoming the dilemma associated with the Al anode.This review firstly underscores the underlying mechanisms of passivation and self-corrosion of Al anode in different electrolytes.Then,specific attentions are paid to Al alloy anode,including the role of various elements and standard processing technology.Finally,general conclusions,current limitations,and future perspectives on Al alloy anode are presented.展开更多
Developing high-efficiency,inexpensive,and steady non-precious metal oxygen reduction reaction(ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery.Here,we have pr...Developing high-efficiency,inexpensive,and steady non-precious metal oxygen reduction reaction(ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery.Here,we have prepared the Cu/Cu_(2)O-NC catalyst with excellent ORR performance and high stability,due to the synergistic effect of Cu and Cu_(2)O nanoparticles.The half-wave potential(0.8 V) and the limiting-current density(5.20 mA/cm^(2)) of the Cu/Cu_(2)O-NC are very close to those of the 20% Pt/C catalyst(0.82 V,5.10 mA/cm^(2)).Besides,it exhibits excellent performance with a maximal power density of 250 mW/cm^(2) and a stable continuous discharge for more than 90 h in the Al-air battery test The promoting effects of Cu_(2)O towards Cu-based ORR catalysts are illustrated as follows:(ⅰ) Cu_(2)O is the major ORR active site by the redox of Cu(Ⅱ)/Cu(Ⅰ),which provides excellent ORR activities;(ⅱ) Cu can stabilize the location of Cu_(2)O by assisting the electron transfer to Cu(Ⅱ)/Cu(Ⅰ) redox,which is conducive to the high stability of the catalyst.This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.展开更多
γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich ox...γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich oxygen vacancies on the surface of γ-MnO2 are verified by morphology, structure,electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy(XPS) results. The oxygen reduction reaction(ORR) electrocatalytic activity of γ-MnO2 is significantly improved by the incoming oxygen vacancies. The γ-MnO2 nanorod-assembled hierarchical micro-spheres calcined under 300 °C in Ar atmosphere show the best ORR performance. The primary Al-air batteries using γ-MnO2 catalysts as the cathode, which demonstrates excellent peal power density of 318 m W cm^(-2) when applying theγ-MnO2 catalysts with optimal amount of oxygen vacancies.展开更多
Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention s...Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention since its first use as an anode in a battery. Its high specific energy （even better volumetric energy density than lithium） makes it ideal for many primary battery applications. However, the development of A1/Air cell with alkaline electrolyte has been lagged behind mainly due to the unfavorable parasitic hydrogen generation. Herein, we designed and constructed a novel A1/H_2/Air tandem fuel cell to turn the adverse parasitic reaction into a useful process. The system consists of two anodes, namely, aluminum and hydrogen, and one common air-breathing cathode. The aluminum acts as both the anode for the A1/Air sub-cell and the source to generate hydrogen for the hydrogen/air sub-cell. The aluminum/air sub-cell has an open circuit voltage of 1.45 V and the H_2/Air sub-cell of 0.95 V. We demonstrated that the maximum power output of aluminum as a fuel was largely enhanced by 31% after incorporating the H_2/Air sub-cell with the tandem concept. In addition, a passive design was utilized in our tandem system to eliminate the dependence on auxiliary pumping sub-systems so that the whole system remained neat and eliminated the dependence of energy consuming pumps or heaters which were typically applied in micro fuel cells.展开更多
The unique hierarchical nitrogen-doped carbon nanocages(h NCNC) are used as a new support to homogeneously immobilize spinel Co Fe_2O_4 nanoparticles by a facile solvothermal method. The so-constructed hierarchical Co...The unique hierarchical nitrogen-doped carbon nanocages(h NCNC) are used as a new support to homogeneously immobilize spinel Co Fe_2O_4 nanoparticles by a facile solvothermal method. The so-constructed hierarchical Co Fe_2O_4/h NCNC catalyst exhibits a high oxygen reduction activity with an onset potential of0.966 V and half-wave potential of 0.819 V versus reversible hydrogen electrode, far superior to the corresponding 0.846 and 0.742 V for its counterpart of Co Fe_2O_4/h CNC with undoped hierarchical carbon nanocages(h CNC) as the support, which locates at the top level for spinel-based catalysts to date.Consequently, the Co Fe_2O_4/h NCNC displays the superior performance to the Co Fe_2O_4/h CNC, when used as the cathode catalysts in the home-made Al-air batteries. X-ray photoelectron spectroscopy characterizations reveal the more charge transfer from Co Fe_2O_4 to h NCNC than to h CNC, indicating the stronger interaction between Co Fe_2O_4 and h NCNC due to the nitrogen participation. The enhanced interaction and hierarchical morphology favor the high dispersion and modification of electronic states for the active species as well as the mass transport during the oxygen reduction process, which plays a significant role in boosting the electrocatalytic performances. In addition, we noticed the high sensitivity of O 1 s spectrum to the particle size and chemical environment for spinel oxides, which is used as an indicator to understand the evolution of ORR activities for all the Co Fe_2O_4-related contrast catalysts. Accordingly,the well-defined structure-performance relationship is demonstrated by the combination of experimental characterizations with theoretical calculations. This study provides a promising strategy to develop efficient, inexpensive and durable oxygen reduction electrocatalysts by tuning the interaction between spinel metal oxides and the carbon-based supports.展开更多
基金supported by the National Natural Science Foundation of China(No.52274302)Natural Science Foundation of Shanghai(Nos.21ZR1429400,22ZR1429700).
文摘The development of non-platinum group metal(non-PGM)and efficient multifunctional electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and hydrogen evolution reaction(HER)with high activity and stability remains a great challenge.Herein,by in-situ transforming silver manganese composite oxide heterointerface into boosted Mott-Schottky heterointerface through a facile carbon reduction strategy,a nanorod-like silver/manganese oxide with superior multifunctional catalytic activities for ORR,OER and HER and stability was obtained.The nanorod-like silver/manganese oxide with Mott-Schottky heterointerface(designated as Ag/Mn_(3)O_(4))exhibits an ORR half-wave potential of 0.831 V(vs.RHE)in 0.1 M KOH,an OER overpotential of 338 mV and a HER overpotential of 177 mV at the current density of 10 mA·cm^(-2)in 1 M KOH,contributing to its noble-metal benchmarks comparable performance in aqueous aluminum-air(Al-air)battery and laboratorial overall water splitting electrolytic cell.Moreover,in-situ electrochemical Raman and synchrotron radiation spectroscopic measurements were conducted to further illustrate the catalytic mechanism of Ag/Mn_(3)O_(4)Mott-Schottky heterointerface towards various electrocatalytic reactions.At the heterointerface,the Ag phase serves as the electron donor and the active phase for ORR and HER,while the Mn_(3)O_(4)phase serves as the electron acceptor and the active phase for OER,respectively.This work deepens the understanding of the Mott-Schottky effect on electrocatalysis and fills in the gap in fundamental physical principles that are behind measured electrocatalytic activity,which offers substantial implications for the rational design of cost-effective multifunctional electrocatalysts with Mott-Schottky effect.
基金supported by the National Natural Science Foundation of China (Grant Nos. U1137601 and 51466005)the Science and Technology Program of Yunnan Province (Grant No.2014RD016)the Program for Innovative Research Team of Yunnan Province (Grant No. 2014HC013)
文摘LaMnO3 catalysts with three-dimensionally ordered holes perovskite structure were prepared via closepacked SiO2 template synthesized by Stober-Frink method. SEM, XRD and BET were employed to characterize the microstructure, phases and specific surface area. CV method was used to the oxygen electrode beha-vior of catalysts. Diameter of the holes was about 330 nm, corresponding to the size of SiO2 template. Full-cell discharge tests were performed on aluminum-air battery fabricated by porous LaMnO3.Results showed that the discharge performance of porous LaMnO3 were 1.54 V, 1.42 V and 1.24 V respectively when the discharge currents were set at 5 mA/cm^2,10 mA/cm^2 and 20 mA/cm^2, respectively, which were higher than that of LaMnO3 prepared by coprecipitation method（1.33 V, 1.09 V, 0.63 V, respectively）.
基金the SZSTI of Shenzhen Municipal Government (JCYJ20170818141758464)the CRCG grant of the University of Hong Kong (201910160008)for providing funding support to the project.
文摘Conventional Al-air battery has many disadvantages for miniwatt applications,such as the complex water management,bulky electrolyte storage and potential leakage hazard.Moreover,the self-corrosion of Al anode continues even when the electrolyte flow is stopped,leading to great Al waste.To tackle these issues,an innovative cotton-based aluminum-air battery is developed in this study.Instead of flowing alkaline solution,cotton substrate pre-deposited with solid alkaline is used,together with a small water reservoir to continuously wet the cotton and dissolve the alkaline in-situ.In this manner,the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir,while the thick aluminum anode can be reused for tens of times until complete consumption.The cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte,leading to a high peak power density of 73 mW cm^(-2) and a high specific energy of 930 mW h g^(-1).Moreover,the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline,so that it can be precisely controlled according to the mission profile to avoid Al waste.Finally,a two-cell battery pack with common water reservoir is developed,which can provide a voltage of 2.7 V and a power output of 223.8 mW.With further scaling-up and stacking,this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.
基金This work is supported by the Equipment Pre-research Laboratory Foundation in Central South University,China(No.6142912200104).
文摘The effects of 0.01 wt.%Ga on microstructure and electrochemical performance of Al−0.4Mg−0.05Sn−0.03Hg anodes in NaOH solutions were investigated.Potentiodynamic polarization,electrochemical impedance spectroscopy,and galvanostatic discharge tests were used to assess the electrochemical performance of the Al−Mg−Sn−Hg−Ga anodes.The results show that the addition of 0.01 wt.%Ga in Al−0.4Mg−0.05Sn−0.03Hg anode enhances its corrosion resistance and discharge activity.It is benefited from the refined second phases and homogenous microstructure of Al−Mg−Sn−Hg−Ga anode,which restrains the local crystallographic corrosion and chunk effect.Compared with Al−Mg−Sn−Hg anode,the corrosion current density and the mass loss rate of Al−Mg−Sn−Hg−Ga anode decrease by 57%and 93%,respectively.When discharging at the current density of 20 mA/cm^(2),the discharge voltage,current efficiency and specific capacity of the single Al−air battery with Al−0.4Mg−0.05Sn−0.03Hg−0.01Ga anode are 1.46 V,33.1%,and 1019.2 A·h·kg^(−1),respectively.The activation mechanism of Ga on Al−Mg−Sn−Hg−Ga anode materials was also discussed.
基金the SZSTI of Shenzhen Municipal Government (JCYJ20170818141758464)the CRCG grant of the University of Hong Kong (201910160008)。
文摘Hydrogel electrolyte is especially suitable for solid-state Al-air batteries targeted for various portable applications, which may, however, lead to continuous Al corrosion during battery standby. To tackle this issue, an ethanol gel electrolyte is developed for Al-air battery for the first time in this work, by using KOH as solute and polyethylene oxide as gelling agent. The ethanol gel is found to effectively inhibit Al corrosion compared with the water gel counterpart, leading to stable Al storage. When assembled into an Al-air battery, the ethanol gel electrolyte achieves a much improved discharge lifetime and specific capacity, which are 5.3 and 4.1 times of the water gel electrolyte at 0.1 mA cm^(-2), respectively.By studying the gel properties, it is found that a lower ethanol purity can improve the battery power output, but at the price of decreased discharge efficiency. On the contrary, a higher polymer concentration will decrease the power output, but can bring extra benefit to the discharge efficiency. As for the gel thickness, a moderate value of 1 mm is preferred to balance the power output and energy efficiency. Finally, to cater the increasing market of flexible electronics, a flexible Al-air battery is developed by impregnating the ethanol gel into a paper substrate, which can function normally even under serious deformation or damage.
基金supported in China by the National Natural Science Foundation of China(No.51474255)the Hunan Provincial Science and Technology Plan Project,China(No.2016TP1007)the Open Sharing Fund for the Large-scale Instruments and Equipments of Central South University(CSUZC201932)。
文摘Developing large-scale and highly efficient oxygen reduction reaction(ORR)catalysts acts a vital role in realizing wide application of metal–air batteries.Here,we propose a gas-foaming strategy to fabricate sustainable and 3D hierarchically porous N-doped carbon with high specific surface area and abundant defects sites derived from biomass.The obtained catalyst exhibits prominent ORR property with higher half-wave potential(0.861 V)and slightly lower kinetic current density(32.44 m A cm^-2),compared to Pt/C(0.856 V and 43.61 m A cm^-1).Furthermore,employing it as catalyst of air cathode,the Al–air battery delivers remarkable discharge performance with excellent power density of 401 m W cm^-2,distinguished energy density of 2453.4 Wh kg^-1 and extremely high open-circuit voltage of 1.85 V among the reported metal–air batteries in the literatures.This gas-foaming strategy for full utilization of biomass affords a chance to explore scalable advanced catalysts in metal–air battery.
基金financially supported by the National Nature Science Foundation of China(Nos.21975289,21905306 and U19A2019)the Hunan Provincial Science and Technology Plan Project,China(Nos.2017TP1001 and2018RS3009)+1 种基金the Key Areas Research and Development Plan of Hunan Province(No.2019GK2033)the Key-Area Research and Development Program of Guangdong Province(No.2020B090919001)。
文摘Aluminum-air(Al-air) batteries are promising candidates for energy storage applications because of their high theoretical energy density and low cost.Nevertheless,their developments have been severely hindered by multiple obstacles,among which the activation and self-corrosion inhibition of Al anode have been considered to be significant challenges.In neutral electrolytes,the main problem is the activation of Al anode,while the self-corrosion of Al anode becomes dominant in alkaline electrolytes.Considerable efforts have been devoted to overcoming the dilemma associated with the Al anode.This review firstly underscores the underlying mechanisms of passivation and self-corrosion of Al anode in different electrolytes.Then,specific attentions are paid to Al alloy anode,including the role of various elements and standard processing technology.Finally,general conclusions,current limitations,and future perspectives on Al alloy anode are presented.
基金financially supported by the National Key R&D Program of China (No.2019YFA0210300)National Nature Science Foundation of China (No.21671200)+1 种基金Hunan Provincial Science and Technology Plan Project of China (Nos.2017TP1001,2018RS3009 and 2019GK2033)financial support from The Open Project Program of Key Laboratory of Preparation and Application of Environmental Friendly Materials (No.2019006),Ministry of Education。
文摘Developing high-efficiency,inexpensive,and steady non-precious metal oxygen reduction reaction(ORR) catalysts to displace Pt-based catalysts is significant for commercial applications of Al-air battery.Here,we have prepared the Cu/Cu_(2)O-NC catalyst with excellent ORR performance and high stability,due to the synergistic effect of Cu and Cu_(2)O nanoparticles.The half-wave potential(0.8 V) and the limiting-current density(5.20 mA/cm^(2)) of the Cu/Cu_(2)O-NC are very close to those of the 20% Pt/C catalyst(0.82 V,5.10 mA/cm^(2)).Besides,it exhibits excellent performance with a maximal power density of 250 mW/cm^(2) and a stable continuous discharge for more than 90 h in the Al-air battery test The promoting effects of Cu_(2)O towards Cu-based ORR catalysts are illustrated as follows:(ⅰ) Cu_(2)O is the major ORR active site by the redox of Cu(Ⅱ)/Cu(Ⅰ),which provides excellent ORR activities;(ⅱ) Cu can stabilize the location of Cu_(2)O by assisting the electron transfer to Cu(Ⅱ)/Cu(Ⅰ) redox,which is conducive to the high stability of the catalyst.This work provides a useful strategy for enhancing the ORR performance of Cu-based catalysts.
基金supported by the National Natural Science Foundation of China (21975163, 51902204)。
文摘γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich oxygen vacancies on the surface of γ-MnO2 are verified by morphology, structure,electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy(XPS) results. The oxygen reduction reaction(ORR) electrocatalytic activity of γ-MnO2 is significantly improved by the incoming oxygen vacancies. The γ-MnO2 nanorod-assembled hierarchical micro-spheres calcined under 300 °C in Ar atmosphere show the best ORR performance. The primary Al-air batteries using γ-MnO2 catalysts as the cathode, which demonstrates excellent peal power density of 318 m W cm^(-2) when applying theγ-MnO2 catalysts with optimal amount of oxygen vacancies.
文摘Metal/Air batteries are considered to be promising electricity storage devices given their compactness, environmental benignity and affordability. As a commonly available metal, aluminum has received great attention since its first use as an anode in a battery. Its high specific energy （even better volumetric energy density than lithium） makes it ideal for many primary battery applications. However, the development of A1/Air cell with alkaline electrolyte has been lagged behind mainly due to the unfavorable parasitic hydrogen generation. Herein, we designed and constructed a novel A1/H_2/Air tandem fuel cell to turn the adverse parasitic reaction into a useful process. The system consists of two anodes, namely, aluminum and hydrogen, and one common air-breathing cathode. The aluminum acts as both the anode for the A1/Air sub-cell and the source to generate hydrogen for the hydrogen/air sub-cell. The aluminum/air sub-cell has an open circuit voltage of 1.45 V and the H_2/Air sub-cell of 0.95 V. We demonstrated that the maximum power output of aluminum as a fuel was largely enhanced by 31% after incorporating the H_2/Air sub-cell with the tandem concept. In addition, a passive design was utilized in our tandem system to eliminate the dependence on auxiliary pumping sub-systems so that the whole system remained neat and eliminated the dependence of energy consuming pumps or heaters which were typically applied in micro fuel cells.
基金supported by the National Natural Science Foundation of China (21473089, 51232003, 21373108, 21573107, and 51571110)the National Basic Research Program of China (2013CB932902)+2 种基金Changzhou Technology Support Program (CE20130032)Priority Academic Program Development of Jiangsu Higher Education InstitutionsFundamental Research Funds for the Central Universities
文摘The unique hierarchical nitrogen-doped carbon nanocages(h NCNC) are used as a new support to homogeneously immobilize spinel Co Fe_2O_4 nanoparticles by a facile solvothermal method. The so-constructed hierarchical Co Fe_2O_4/h NCNC catalyst exhibits a high oxygen reduction activity with an onset potential of0.966 V and half-wave potential of 0.819 V versus reversible hydrogen electrode, far superior to the corresponding 0.846 and 0.742 V for its counterpart of Co Fe_2O_4/h CNC with undoped hierarchical carbon nanocages(h CNC) as the support, which locates at the top level for spinel-based catalysts to date.Consequently, the Co Fe_2O_4/h NCNC displays the superior performance to the Co Fe_2O_4/h CNC, when used as the cathode catalysts in the home-made Al-air batteries. X-ray photoelectron spectroscopy characterizations reveal the more charge transfer from Co Fe_2O_4 to h NCNC than to h CNC, indicating the stronger interaction between Co Fe_2O_4 and h NCNC due to the nitrogen participation. The enhanced interaction and hierarchical morphology favor the high dispersion and modification of electronic states for the active species as well as the mass transport during the oxygen reduction process, which plays a significant role in boosting the electrocatalytic performances. In addition, we noticed the high sensitivity of O 1 s spectrum to the particle size and chemical environment for spinel oxides, which is used as an indicator to understand the evolution of ORR activities for all the Co Fe_2O_4-related contrast catalysts. Accordingly,the well-defined structure-performance relationship is demonstrated by the combination of experimental characterizations with theoretical calculations. This study provides a promising strategy to develop efficient, inexpensive and durable oxygen reduction electrocatalysts by tuning the interaction between spinel metal oxides and the carbon-based supports.
