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
Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrol...Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrolysis due to sluggish OER kinetics.Thus,it’s much desirable to explore the efficient and earth-abundant transition-metal-based OER electrocatalysts with high current density and superior stability for industrial alkaline electrolyzers.Herein,we demonstrate a significant enhancement of OER kinetics with the hybrid electrocatalyst arrays in alkaline via judiciously combining earth-abundant and ultrathin NiCo-based layered double hydroxide(NiCo LDH)nanosheets with nickel cobalt sulfides(NiCoS)with a facile metal-organic framework(MOF)-template-involved surface sulfidation process.The obtained NiCo LDH/NiCoS hybrid arrays exhibits an extremely low OER overpotential of 308 mV at 100 mA·cm^(−2),378 mV at 200 mA·cm^(−2)and 472 mV at 400 mA·cm^(−2)in 1 M KOH solution,respectively.A much low Tafel slope of 48 mV·dec^(−1)can be achieved.Meanwhile,with the current density from 50 to 250 mA·cm^(−2),the NiCo-LDH/NiCoS hybrid arrays can run for 25 h without any degradation.Our results demonstrate that the construction of hybrid arrays with abundant interfaces of NiCo LDH/NiCoS can facilitate OER kinetics via possible modulation of binding energy of O-containing intermediates in alkaline media.The present work would pave the way for the development of lowcost and efficient OER catalysts and industrial application of water alkaline electrolyzers.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
Green hydrogen production via seawater electrolysis holds a great promise for carbon-neutral energy production. However, the development of efficient and low-cost bifunctional electrocatalysts for seawater electrolysi...Green hydrogen production via seawater electrolysis holds a great promise for carbon-neutral energy production. However, the development of efficient and low-cost bifunctional electrocatalysts for seawater electrolysis at an industrial level remains a significant challenge. Herein, we report a facile approach based on one-dimensional (1D) cobalt carbonate hydroxide (CCH) nanoneedles (NNs) as skeleton and zeolitic imidazolate framework-67 (ZIF-67) as a sacrificial template to construct a self-supported NiCo layered double hydroxide (NiCo LDH) heterostructure nanocage (CCH@NiCo LDH) anchoring on the carbon felt (CF). The NiCo LDHs have hollow features, consisting of ultrathin layered hydroxide nanosheets. Benefiting from the structural advantages, unique carbon substrate and desirable composition, three-dimensional (3D) NiCo LDH nanocages exhibit superior performance as a bifunctional catalyst for overall seawater splitting at an industrial level and good corrosion resistance in alkaline media. In the alkaline seawater (1 M KOH + 0.5 M NaCl), it exhibits low overpotentials of 356 mV for hydrogen evolution reaction (HER) and 433 mV for oxygen evolution reaction (OER) at 400 mA·cm^(−2), much better than most of reported non-noble metal catalysts. Consequently, the obtained CF electrode loading of CCH@NiCo LDH exhibits outstanding performance as anodes and cathodes for overall alkaline seawater splitting, with remarkably low cell voltages of 1.56 and 1.89 V at current densities of 10 and 400 mA·cm^(−2), respectively. Moreover, the robust stability of 100 h is also demonstrated at above 200 mA·cm^(−2) in alkaline seawater. Our present work demonstrates significant potential for constructing effective cost-efficient and non-noble-metal bifunctional electrocatalyst and electrode for industrial seawater splitting.展开更多
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supports from the National Natural Science Foundation of China(Nos.51908408 and 21872104)the Natural Science Foundation of Tianjin for Distinguished Young Scholar(No.20JCJQJC00150)+1 种基金Innovative Research Team of Tianjin Municipal Education Commission(No.TD13-5008)D.M.acknowledges the support from the Tencent Foundation through the XPLORER PRIZE.
文摘Carbon-free hydrogen as a promising clean energy source can be produced with electrocatalysts via water electrolysis.Oxygen evolution reaction(OER)as anodic reaction determines the overall efficiency of water electrolysis due to sluggish OER kinetics.Thus,it’s much desirable to explore the efficient and earth-abundant transition-metal-based OER electrocatalysts with high current density and superior stability for industrial alkaline electrolyzers.Herein,we demonstrate a significant enhancement of OER kinetics with the hybrid electrocatalyst arrays in alkaline via judiciously combining earth-abundant and ultrathin NiCo-based layered double hydroxide(NiCo LDH)nanosheets with nickel cobalt sulfides(NiCoS)with a facile metal-organic framework(MOF)-template-involved surface sulfidation process.The obtained NiCo LDH/NiCoS hybrid arrays exhibits an extremely low OER overpotential of 308 mV at 100 mA·cm^(−2),378 mV at 200 mA·cm^(−2)and 472 mV at 400 mA·cm^(−2)in 1 M KOH solution,respectively.A much low Tafel slope of 48 mV·dec^(−1)can be achieved.Meanwhile,with the current density from 50 to 250 mA·cm^(−2),the NiCo-LDH/NiCoS hybrid arrays can run for 25 h without any degradation.Our results demonstrate that the construction of hybrid arrays with abundant interfaces of NiCo LDH/NiCoS can facilitate OER kinetics via possible modulation of binding energy of O-containing intermediates in alkaline media.The present work would pave the way for the development of lowcost and efficient OER catalysts and industrial application of water alkaline electrolyzers.
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.
基金supported by the National Natural Science Foundation of China(Nos.51908408 and 21872104)Natural Science Foundation of Tianjin for Distinguished Young Scholar,China(No.20JCJQJC00150).
文摘Green hydrogen production via seawater electrolysis holds a great promise for carbon-neutral energy production. However, the development of efficient and low-cost bifunctional electrocatalysts for seawater electrolysis at an industrial level remains a significant challenge. Herein, we report a facile approach based on one-dimensional (1D) cobalt carbonate hydroxide (CCH) nanoneedles (NNs) as skeleton and zeolitic imidazolate framework-67 (ZIF-67) as a sacrificial template to construct a self-supported NiCo layered double hydroxide (NiCo LDH) heterostructure nanocage (CCH@NiCo LDH) anchoring on the carbon felt (CF). The NiCo LDHs have hollow features, consisting of ultrathin layered hydroxide nanosheets. Benefiting from the structural advantages, unique carbon substrate and desirable composition, three-dimensional (3D) NiCo LDH nanocages exhibit superior performance as a bifunctional catalyst for overall seawater splitting at an industrial level and good corrosion resistance in alkaline media. In the alkaline seawater (1 M KOH + 0.5 M NaCl), it exhibits low overpotentials of 356 mV for hydrogen evolution reaction (HER) and 433 mV for oxygen evolution reaction (OER) at 400 mA·cm^(−2), much better than most of reported non-noble metal catalysts. Consequently, the obtained CF electrode loading of CCH@NiCo LDH exhibits outstanding performance as anodes and cathodes for overall alkaline seawater splitting, with remarkably low cell voltages of 1.56 and 1.89 V at current densities of 10 and 400 mA·cm^(−2), respectively. Moreover, the robust stability of 100 h is also demonstrated at above 200 mA·cm^(−2) in alkaline seawater. Our present work demonstrates significant potential for constructing effective cost-efficient and non-noble-metal bifunctional electrocatalyst and electrode for industrial seawater splitting.
