Lithium-ion capacitors(LICs) combining the advantages of lithium-ion batteries and supercapacitors are considered a promising nextgeneration energy storage device. However, the sluggish kinetics of battery-type anode ...Lithium-ion capacitors(LICs) combining the advantages of lithium-ion batteries and supercapacitors are considered a promising nextgeneration energy storage device. However, the sluggish kinetics of battery-type anode cannot match the capacitor-type cathode, restricting the development of LICs. Herein, hierarchical carbon framework(HCF) anode material composed of 0D carbon nanocage bridged with 2D graphene network are developed via a template-confined synthesis process. The HCF with nanocage structure reduces the Li^(+) transport path and benefits the rapid Li^(+) migration, while 2D graphene network can promote the electron interconnecting of carbon nanocages. In addition, the doped N atoms in HCF facilitate to the adsorption of ions and enhance the pseudo contribution, thus accelerate the kinetics of the anode. The HCF anode delivers high specific capacity, remarkable rate capability. The LIC pouch-cell based on HCF anode and active HCF(a-HCF) cathode can provide a high energy density of 162 Wh kg^(-1) and a superior power density of 15.8 kW kg^(-1), as well as a long cycling life exceeding 15,000cycles. This study demonstrates that the well-defined design of hierarchical carbon framework by incorporating 0D carbon nanocages and 2D graphene network is an effective strategy to promote LIC anode kinetics and hence boost the LIC electrochemical performance.展开更多
The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO_(2)reduction reaction is challenging.Due to the complexity of catalytic systems,convention...The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO_(2)reduction reaction is challenging.Due to the complexity of catalytic systems,conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active sites.Herein,operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(Ⅱ)phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis system.Comprehensive X-ray spectroscopy analyses,including surface sensitive△μspectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation,were used to discover that Cu species aggregated with increasing applied potential,which is responsible for the observed evolution of C_(2)H_(4).The approach developed in this work,characterizing the active-site geometry and dynamic structural change,is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to con tribute to the rational design of highly effective catalysts.展开更多
Lithium slurry flow cell(LSFC)is a novel energy storage device that combines the concept of both lithium ion batteries(LIBs)and flow batteries(FBs).Although it is hoped to inherit the advantages of both LIBs and FBs,s...Lithium slurry flow cell(LSFC)is a novel energy storage device that combines the concept of both lithium ion batteries(LIBs)and flow batteries(FBs).Although it is hoped to inherit the advantages of both LIBs and FBs,such as high energy density,ease of fabrication,environmental friendly,independent energy and power density,to name but a few.While unfortunately,it still has many challenges to overcome before it becoming the future star in energy storage area.Here in this paper,we briefly recall its history and try to illustrate the main issues that hindering its research as well as application.As a typical interdisciplinary product,LSFC is definitely a promising candidate for large scale energy storage application,while obviously it still has a long way to go.展开更多
The Ru-catalyzed carbonylation of alkenes with CO_(2)as a C1 surrogate and imidazole chlorides as the promotor is investigated by a combination of computational and experimental study.The conversion rate of CO_(2)to C...The Ru-catalyzed carbonylation of alkenes with CO_(2)as a C1 surrogate and imidazole chlorides as the promotor is investigated by a combination of computational and experimental study.The conversion rate of CO_(2)to CO is positively correlated with the efficiency of both hydroesterification and hydroformylation,which is found facilitated in the presence of chloride additives with a decreasing order of BmimCl~B3MimCl>BmmimCl~LiCl.Taking the hydroesterification with MeOH as a representative example,BmimCl bearing C-H functionality at the C^(2)site of the cation assists the reduction of CO_(2)to CO as a hydrogen donor medium,with the anion and cation acting in a synergistic fashion.Subsequent insertion of CO_(2)into the formed Ru-H bond with the assistance of chloride anion produces the Ru-COOH species,which ultimately accelerates the activation of CO_(2).展开更多
N-doped reduced graphene oxide quantum dots(N-rGQDs) have attracted more and more attention in efficient catalytic degradation of aqueous organic pollutants.However,the synthesis of N-rGQDs is generally a complex and ...N-doped reduced graphene oxide quantum dots(N-rGQDs) have attracted more and more attention in efficient catalytic degradation of aqueous organic pollutants.However,the synthesis of N-rGQDs is generally a complex and high energy required process for the reduction and N-doping steps.In this study,a facile and green fabrication approach of N-rGQDs is established,based on a metal-free Fenton reaction without additional energy-input.The N structures of N-rGQDs play a significant role in the promotion of their catalytic performance.The N-rGQDs with relatively high percentage of aromatic nitrogen(NAr-rGQDs) perform excellent catalytic activities,with which the degradation efficiency of pollutant is enhanced by 25 times.Density functional theory(DFT) calculation also indicates aromatic nitrogen structures with electron-rich sites are prone to transfer electron,presenting a key role in the catalytic reaction.This metal-free Fenton process provides a green and costeffective strategy for one-step fabrication of N-rGQDs with controllable features and potential environmental catalytic applications.展开更多
基金the financial support by the National Science Foundation of China(51822706 and 52107234)Beijing Natural Science Foundation(JQ19012)+2 种基金the DNL Cooperation Fund,CAS(DNL201912 and DNL201915)Innovation Academy for Green Manufacture Fund(IAGM2020C02)Youth Innovation Promotion Association,CAS(Y2021052).
文摘Lithium-ion capacitors(LICs) combining the advantages of lithium-ion batteries and supercapacitors are considered a promising nextgeneration energy storage device. However, the sluggish kinetics of battery-type anode cannot match the capacitor-type cathode, restricting the development of LICs. Herein, hierarchical carbon framework(HCF) anode material composed of 0D carbon nanocage bridged with 2D graphene network are developed via a template-confined synthesis process. The HCF with nanocage structure reduces the Li^(+) transport path and benefits the rapid Li^(+) migration, while 2D graphene network can promote the electron interconnecting of carbon nanocages. In addition, the doped N atoms in HCF facilitate to the adsorption of ions and enhance the pseudo contribution, thus accelerate the kinetics of the anode. The HCF anode delivers high specific capacity, remarkable rate capability. The LIC pouch-cell based on HCF anode and active HCF(a-HCF) cathode can provide a high energy density of 162 Wh kg^(-1) and a superior power density of 15.8 kW kg^(-1), as well as a long cycling life exceeding 15,000cycles. This study demonstrates that the well-defined design of hierarchical carbon framework by incorporating 0D carbon nanocages and 2D graphene network is an effective strategy to promote LIC anode kinetics and hence boost the LIC electrochemical performance.
基金supported by the National Natural Science Foundation of China,grant number:U1732267.
文摘The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO_(2)reduction reaction is challenging.Due to the complexity of catalytic systems,conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active sites.Herein,operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(Ⅱ)phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis system.Comprehensive X-ray spectroscopy analyses,including surface sensitive△μspectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation,were used to discover that Cu species aggregated with increasing applied potential,which is responsible for the observed evolution of C_(2)H_(4).The approach developed in this work,characterizing the active-site geometry and dynamic structural change,is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to con tribute to the rational design of highly effective catalysts.
基金by National Key Research and Development Program of China(No.2019YFA0705600)National Natural Science Foundation of China(No.21706261)+1 种基金Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.21921005)Beijing Natural Science Foundation(No.L172045).
文摘Lithium slurry flow cell(LSFC)is a novel energy storage device that combines the concept of both lithium ion batteries(LIBs)and flow batteries(FBs).Although it is hoped to inherit the advantages of both LIBs and FBs,such as high energy density,ease of fabrication,environmental friendly,independent energy and power density,to name but a few.While unfortunately,it still has many challenges to overcome before it becoming the future star in energy storage area.Here in this paper,we briefly recall its history and try to illustrate the main issues that hindering its research as well as application.As a typical interdisciplinary product,LSFC is definitely a promising candidate for large scale energy storage application,while obviously it still has a long way to go.
基金Financial support from National Natural Science Foundation of China (22078336, U1662133, 21773158, 22008238)Innovation Academy for Green Manufacture, CAS (IAGM2020C13) is gratefully acknowledged
文摘The Ru-catalyzed carbonylation of alkenes with CO_(2)as a C1 surrogate and imidazole chlorides as the promotor is investigated by a combination of computational and experimental study.The conversion rate of CO_(2)to CO is positively correlated with the efficiency of both hydroesterification and hydroformylation,which is found facilitated in the presence of chloride additives with a decreasing order of BmimCl~B3MimCl>BmmimCl~LiCl.Taking the hydroesterification with MeOH as a representative example,BmimCl bearing C-H functionality at the C^(2)site of the cation assists the reduction of CO_(2)to CO as a hydrogen donor medium,with the anion and cation acting in a synergistic fashion.Subsequent insertion of CO_(2)into the formed Ru-H bond with the assistance of chloride anion produces the Ru-COOH species,which ultimately accelerates the activation of CO_(2).
基金funding by National Natural Science Foundation of China (No. 51978643)Youth Innovation Promotion Association of CAS (Y201814)The National Youth Talent Support Program of China。
文摘N-doped reduced graphene oxide quantum dots(N-rGQDs) have attracted more and more attention in efficient catalytic degradation of aqueous organic pollutants.However,the synthesis of N-rGQDs is generally a complex and high energy required process for the reduction and N-doping steps.In this study,a facile and green fabrication approach of N-rGQDs is established,based on a metal-free Fenton reaction without additional energy-input.The N structures of N-rGQDs play a significant role in the promotion of their catalytic performance.The N-rGQDs with relatively high percentage of aromatic nitrogen(NAr-rGQDs) perform excellent catalytic activities,with which the degradation efficiency of pollutant is enhanced by 25 times.Density functional theory(DFT) calculation also indicates aromatic nitrogen structures with electron-rich sites are prone to transfer electron,presenting a key role in the catalytic reaction.This metal-free Fenton process provides a green and costeffective strategy for one-step fabrication of N-rGQDs with controllable features and potential environmental catalytic applications.
