Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets ...Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.展开更多
Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are stil...Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.展开更多
A well-designed cobalt-based metal organic framework(Co-MOF)derived NiCo layered doubleh ydroxides(NiCo-LDH)three-dimensional porous nanostructures has been fabricated on carbon cloth(CC)b y the ion etching/exchange r...A well-designed cobalt-based metal organic framework(Co-MOF)derived NiCo layered doubleh ydroxides(NiCo-LDH)three-dimensional porous nanostructures has been fabricated on carbon cloth(CC)b y the ion etching/exchange reaction method. The morphology and structure of the synthesized samples have been characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmissione lectron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS). As an electrode,the optimalN iCo-LDH shows a high specific capacity of 226.3mA·h/g at1A/g. The hybrid supercapacitor(HSC)b ased on NiCo-LDH electrode and activated carbon(AC)achieves a specific energy of 27.39W·h/kg withe xcellent cycling stability(capacity retention of 93.5% after 5000 cycles).展开更多
The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is challenging.Herein,the carbon nanotubes(CNTs)coupled with lowcrystalli...The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is challenging.Herein,the carbon nanotubes(CNTs)coupled with lowcrystalline sulfur and nitrogen co-doped Ni Co-LDH(denoted as SN-Ni Co-LDH)nanosheets array are grown on Ni Co foam(NCF)substrate by two convenient steps of metal induced self-assembly and corrosion engineering,which present the advantages of operating at roomtemperature and low preparation costs.Benefiting from the S–N co-doping and low-crystallinity of Ni Co-LDH,the prepared SN-Ni Co-LDH@CNTs@NCF electrode presents a topping charge capacity of 2470 C·g^(-1)(4.94 C·cm^(-2))at 5 m A·cm^(-2).Furthermore,the fabricated asymmetry supercapacitor(ASC)achieves an extraordinary energy density of 77 Wh·kg^(-1)(0.617 m Wh·cm^(-2))at a power density of 438 W·kg^(-1)(3.5 m W·cm^(-2))and outstanding stability(91%capacity retention after 5000 cycles at20 m A·cm^(-2)).Impressively,the structure evolution of Ni Co-LDH during the charge/discharge processes has been thoroughly elucidated by in-situ Raman spectra.Therefore,this work verifies a powerful strategy and practical value for preparing composite electrodes with high supercapacitance performance,and also provides guidance for the rational design of the smart electrodes.展开更多
The rational fabrication of highly efficient electrocatalysts with low cost toward oxygen evolution reaction(OER)is greatly desired but remains a formidable challenge.In this work,we present a facile and straightforwa...The rational fabrication of highly efficient electrocatalysts with low cost toward oxygen evolution reaction(OER)is greatly desired but remains a formidable challenge.In this work,we present a facile and straightforward method of incorporating NiCo-layered double hydroxide(NiCo-LDH)into GO-dispersed CNTs(GO-CNTs)with interconnected configuration.X-ray absorption spectroscopy(XAS)reveals the strong electron interaction between NiCo-LDH and the underlying GO-CNTs substrate,which is supposed to facilitate charge transfer and accelerate the kinetics for OER.By tuning the amount of CNTs,the optimized NiCo-LDH/GO-CNTs composite can achieve a low overpotential of 290 mV at 10 mA·cm^(−2) current density,a small Tafel slope of 66.8 mV·dec^(−1) and robust stability,superior to the pure NiCo-LDH and commercial RuO_(2) in alkaline media.The preeminent oxygen evolution performance is attributed to the synergistic effect stemming from the merits and the intimate electron interaction between LDH and GO-CNTs.This allows NiCo-LDH/GO-CNTs to be potentially applied in an industrial non-noble metal-based water electrolyzer as the anodic catalysts.展开更多
In this study, a bulk composite material symbolized as NiCo LDH-rGO/Ni F was developed by a solvothermal process for the first time. This material was fabricated through simultaneous growth of nickel-cobalt layered do...In this study, a bulk composite material symbolized as NiCo LDH-rGO/Ni F was developed by a solvothermal process for the first time. This material was fabricated through simultaneous growth of nickel-cobalt layered double hydroxide(NiCo LDH) and reduced graphene oxide(rGO) on nickel foam. This bulk composite can be used directly as a binder-free electrode for supercapacitors(SCs). The physicochemical properties of this composite were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The electrochemical properties of the composite were measured by the cyclic voltammetry and galvanostatic charge-discharge. The results show that this composite had a hierarchical structure and exhibited a significantly enhanced specific capacitance of up to 3383 F/g at 1 A/g. The asymmetric SC using this composite as a positive electrode had a high energy density of 40.54 Wh/kg at the power density of 206.5 W/kg and good cycling stability. Owing to the synergies between the metal oxides and the rGO, the preparation method of in situ growth and its hierarchical structure, this bulk composite displayed excellent electrochemical performance and had a promising application as an efficient electrode for high-performance SCs.展开更多
Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splittin...Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splitting.In this paper, we synthesis a unique structured catalyst that was composed by Co_9S_8 nanowires and nickel cobalt layered double hydroxide(NiCo-LDH) nanosheets. The ultrathin nanosheets decorated on the Co_9S_8 nanoarrays offer large specific surface area, numerous active edge sites and excellent electrical conductivity for fast electron transfer. Benefiting from this heterogeneous structure, the catalyst presents excellent catalytic performance in alkaline media. It requires 168 mV to reach current density of 10 mA/cm^2 for HER and 278 m V to reach current density of 30 mA/cm^2 for OER. When used as electrode in a homemade two-electrode system, it only needs t a voltage of 1.63 V to achieve current densities of 10 mA/cm^2, which proves Co_9S_8@NiCo LDH/NF as a superior bifunctional catalyst for water splitting.展开更多
基金the funding from Natural Science Foundation of China(No.52003163)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515010670)+1 种基金Science and Technology Innovation Commission of Shenzhen(Nos.KQTD20170810105439418 and 20200812112006001)NTUT-SZU Joint Research Program(Nos.2022005 and 2022015)
文摘Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.
基金Rachadapisek Sompoch project,Chulalongkorn University(CU_GR_62_14_62_02)the Energy Conservation and Promotion Fund Office,Ministry of Energy+2 种基金the NSFC(grant 51421091)National Science Foundation for Distinguished Young Scholars for Hebei Province of China(grant E2016203376)Asahi Glass Foundation。
文摘Nickel/cobalt-layered double hydroxides(Ni Co-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery(LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene(Ni Co-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 ? can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and Ni Co-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected,the discharge capacity of 562 m Ah g-1 at 5.0 A g-1 for 800 cycles without degradation can be achieved,rate capability and cycle performance are better than that of NiCo-LDH(~100 mAh g-1). Furthermore, the density function theory(DFT) calculations were performed to demonstrate that Ni Co-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.
基金Sponsored by the National Natural Science Foundation of China(Grant No.21788102)the Science & Technology Nova Program of Jilin Province(Grant No.20200301051RQ)the JLICT Center of Analysis Characterization and Analysis。
文摘A well-designed cobalt-based metal organic framework(Co-MOF)derived NiCo layered doubleh ydroxides(NiCo-LDH)three-dimensional porous nanostructures has been fabricated on carbon cloth(CC)b y the ion etching/exchange reaction method. The morphology and structure of the synthesized samples have been characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmissione lectron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS). As an electrode,the optimalN iCo-LDH shows a high specific capacity of 226.3mA·h/g at1A/g. The hybrid supercapacitor(HSC)b ased on NiCo-LDH electrode and activated carbon(AC)achieves a specific energy of 27.39W·h/kg withe xcellent cycling stability(capacity retention of 93.5% after 5000 cycles).
基金supported by the National Natural Science Foundation of China(Nos.21978111,22278175 and 22108094)Zhejiang Provincial Natural Science Foundation of China(Nos.LZ24B060001 and LY22E020016)+1 种基金Jiaxing Key Research Project(No.2022BZ10001)the“Innovation Jiaxing·Excellent Talent Support Plan”Top Talent for Innovation and Entrepreneurship。
文摘The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is challenging.Herein,the carbon nanotubes(CNTs)coupled with lowcrystalline sulfur and nitrogen co-doped Ni Co-LDH(denoted as SN-Ni Co-LDH)nanosheets array are grown on Ni Co foam(NCF)substrate by two convenient steps of metal induced self-assembly and corrosion engineering,which present the advantages of operating at roomtemperature and low preparation costs.Benefiting from the S–N co-doping and low-crystallinity of Ni Co-LDH,the prepared SN-Ni Co-LDH@CNTs@NCF electrode presents a topping charge capacity of 2470 C·g^(-1)(4.94 C·cm^(-2))at 5 m A·cm^(-2).Furthermore,the fabricated asymmetry supercapacitor(ASC)achieves an extraordinary energy density of 77 Wh·kg^(-1)(0.617 m Wh·cm^(-2))at a power density of 438 W·kg^(-1)(3.5 m W·cm^(-2))and outstanding stability(91%capacity retention after 5000 cycles at20 m A·cm^(-2)).Impressively,the structure evolution of Ni Co-LDH during the charge/discharge processes has been thoroughly elucidated by in-situ Raman spectra.Therefore,this work verifies a powerful strategy and practical value for preparing composite electrodes with high supercapacitance performance,and also provides guidance for the rational design of the smart electrodes.
基金This work was supported by Science and Technology Key Project of Guangdong Province of China(No.2020B010188002)the National Major Science and Technology Program for Water Pollution Control and Treatment of China(No.2017ZX07202)。
文摘The rational fabrication of highly efficient electrocatalysts with low cost toward oxygen evolution reaction(OER)is greatly desired but remains a formidable challenge.In this work,we present a facile and straightforward method of incorporating NiCo-layered double hydroxide(NiCo-LDH)into GO-dispersed CNTs(GO-CNTs)with interconnected configuration.X-ray absorption spectroscopy(XAS)reveals the strong electron interaction between NiCo-LDH and the underlying GO-CNTs substrate,which is supposed to facilitate charge transfer and accelerate the kinetics for OER.By tuning the amount of CNTs,the optimized NiCo-LDH/GO-CNTs composite can achieve a low overpotential of 290 mV at 10 mA·cm^(−2) current density,a small Tafel slope of 66.8 mV·dec^(−1) and robust stability,superior to the pure NiCo-LDH and commercial RuO_(2) in alkaline media.The preeminent oxygen evolution performance is attributed to the synergistic effect stemming from the merits and the intimate electron interaction between LDH and GO-CNTs.This allows NiCo-LDH/GO-CNTs to be potentially applied in an industrial non-noble metal-based water electrolyzer as the anodic catalysts.
基金supported by the National Key Basic Research Program of China ("973" Program, No. 2014CB239702)the National Natural Science Foundation of China (No. 21676082)
文摘In this study, a bulk composite material symbolized as NiCo LDH-rGO/Ni F was developed by a solvothermal process for the first time. This material was fabricated through simultaneous growth of nickel-cobalt layered double hydroxide(NiCo LDH) and reduced graphene oxide(rGO) on nickel foam. This bulk composite can be used directly as a binder-free electrode for supercapacitors(SCs). The physicochemical properties of this composite were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The electrochemical properties of the composite were measured by the cyclic voltammetry and galvanostatic charge-discharge. The results show that this composite had a hierarchical structure and exhibited a significantly enhanced specific capacitance of up to 3383 F/g at 1 A/g. The asymmetric SC using this composite as a positive electrode had a high energy density of 40.54 Wh/kg at the power density of 206.5 W/kg and good cycling stability. Owing to the synergies between the metal oxides and the rGO, the preparation method of in situ growth and its hierarchical structure, this bulk composite displayed excellent electrochemical performance and had a promising application as an efficient electrode for high-performance SCs.
基金supported by the National Natural Science Foundation of China (21571012)
文摘Water electrolysis is considered to be an effective way to fabricate hydrogen, and it is desirable to find the highly efficient, inexpensive and good durability bifunctional electrocatalysts for overall water splitting.In this paper, we synthesis a unique structured catalyst that was composed by Co_9S_8 nanowires and nickel cobalt layered double hydroxide(NiCo-LDH) nanosheets. The ultrathin nanosheets decorated on the Co_9S_8 nanoarrays offer large specific surface area, numerous active edge sites and excellent electrical conductivity for fast electron transfer. Benefiting from this heterogeneous structure, the catalyst presents excellent catalytic performance in alkaline media. It requires 168 mV to reach current density of 10 mA/cm^2 for HER and 278 m V to reach current density of 30 mA/cm^2 for OER. When used as electrode in a homemade two-electrode system, it only needs t a voltage of 1.63 V to achieve current densities of 10 mA/cm^2, which proves Co_9S_8@NiCo LDH/NF as a superior bifunctional catalyst for water splitting.
