Metal/carbon nanocomposites have shown great potential as high-performance,low-cost electrocatalysts owing largely to their unique metal-support interactions.These nanocomposites are typically prepared by conventional...Metal/carbon nanocomposites have shown great potential as high-performance,low-cost electrocatalysts owing largely to their unique metal-support interactions.These nanocomposites are typically prepared by conventional pyrolysis that is tedious and energy-intensive.Herein,we report the ultrafast preparation of cobalt/carbon nanocomposites by magnetic induction heating(MIH)of metal organic frameworks within seconds under an inert atmosphere.The resulting samples consist of cobalt nanoparticles encapsulated within defective carbon shells,and effectively catalyze oxygen evolution reaction(OER)in alkaline media.Among the series,the sample prepared at 400 A for 10 s exhibits the best OER performance,needing a low overpotential of+308 mV to reach the current density of 10 mA cm^(−2),along with excellent stability,and even outperforms commercial RuO_(2) at high overpotentials.This is ascribed to the charge transfer between the carbon scaffold and metal nanoparticles.Operando X-ray absorption spectroscopy measurements show that the electrochemically produced CoOOH species is responsible for the high electrocatalytic performance.The results highlight the unique potential of MIH in the development of effective nanocomposite catalysts for electrochemical energy technologies.展开更多
In this work,we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes(in the range from-2 to-10 nm).Carbon supported nanoparticles with ...In this work,we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes(in the range from-2 to-10 nm).Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures,such as disks or wires.Without using any surfactants,the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential,frequency and electrolyte composition.For instance,application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles;whereas higher frequencies lead to predominantly spherical nanoparticles.On the other hand,the amplitude of the,sinusoidal signal was found to affect the particle size;the lower the amplitude of the applied AC signal,the smaller the resulting particle size.Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is-2 times higher than the state-of-the-art commercial Pt/C catalyst(0.42 A/mg)from Tanaka.In addition to this,we discussed the mechanistic insights about the nanoparticle formation pathways.展开更多
基金National Science Foundation(CHE-1900235 and CHE-2003685)TEM,XPS,and Raman studies were conducted as part of a user project at the National Center for Electron Microscopy and Molecular Foundry,Lawrence Berkeley National Laboratory,which is supported by the Office of Science,Office of Basic Energy Sciences,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231+1 种基金XAS experiments were performed at the Stanford Synchrotron Radiation Lightsource(SSRL),which is supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DE-AC02-76SF00515Q.M.L.acknowledges the ECS Joseph W.Richards Summer Fellowship for funding support and the support of a Grant-in-Aid of Research(G20211001-639)from the National Academy of Sciences,administered by Sigma Xi,The Scientific Research Society.
文摘Metal/carbon nanocomposites have shown great potential as high-performance,low-cost electrocatalysts owing largely to their unique metal-support interactions.These nanocomposites are typically prepared by conventional pyrolysis that is tedious and energy-intensive.Herein,we report the ultrafast preparation of cobalt/carbon nanocomposites by magnetic induction heating(MIH)of metal organic frameworks within seconds under an inert atmosphere.The resulting samples consist of cobalt nanoparticles encapsulated within defective carbon shells,and effectively catalyze oxygen evolution reaction(OER)in alkaline media.Among the series,the sample prepared at 400 A for 10 s exhibits the best OER performance,needing a low overpotential of+308 mV to reach the current density of 10 mA cm^(−2),along with excellent stability,and even outperforms commercial RuO_(2) at high overpotentials.This is ascribed to the charge transfer between the carbon scaffold and metal nanoparticles.Operando X-ray absorption spectroscopy measurements show that the electrochemically produced CoOOH species is responsible for the high electrocatalytic performance.The results highlight the unique potential of MIH in the development of effective nanocomposite catalysts for electrochemical energy technologies.
基金support from Deutsche Forschungsgemeinschaft under Germany s excellence strategy-EXC 2089/1-390776260Germany’s excellence cluster“e-conversion”,DFG project BA 5795/4-1funding from the TUM IGSSE project 11.01 are gratefully acknowledged.We also acknowledge DESY(Hamburg,Germany),a member of the Helmholtz Association HGF,for the provision of experimental facilities.Parts of this research were carried out at PETRA III using beamline P02.1.We acknowledge CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110) and CEITEC Nano Research Infrastructure for TEM measurements.
文摘In this work,we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes(in the range from-2 to-10 nm).Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures,such as disks or wires.Without using any surfactants,the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential,frequency and electrolyte composition.For instance,application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles;whereas higher frequencies lead to predominantly spherical nanoparticles.On the other hand,the amplitude of the,sinusoidal signal was found to affect the particle size;the lower the amplitude of the applied AC signal,the smaller the resulting particle size.Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is-2 times higher than the state-of-the-art commercial Pt/C catalyst(0.42 A/mg)from Tanaka.In addition to this,we discussed the mechanistic insights about the nanoparticle formation pathways.
