The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique ...The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique morphologies is crucial for enhancing the stability of PEMFCs.In this study,we synthesized a novel PtCu nano-dendrite(PtCuND)catalyst through a facile,one-step solvothermal process.The sub-nanometer particles and nanopores within this catalyst facilitate enhanced mass transport.In PEM single-cell tests,the PtCuND catalyst displays high activity and robust stability,achieving a mass activity of 0.65 A mgPt^(–1).Notably,after accelerated durability tests,the mass activity and the voltage at 0.8 A cm^(–2)of PtCuND exhibits only minimal decreases of 18.5%and 9 mV,respectively.The combined experimental results and theoretical calculations conclusively illustrate the optimized adsorption of oxygen species and the impact of compressive strain on the catalyst surface.The enhanced durability can be attributed to the maintained nano-dendritic morphology and the strengthened interaction within the Pt-Cu bonds.This work not only enhances the stability of PEMFCs but also provides a robust foundation for the future scaling up of catalyst production,paving the way for widespread application in sustainable energy systems.展开更多
The application of direct ethanol fuel cell(DEFC)has been bottlenecked by the sluggish ethanol oxidation reaction(EOR).Efficient electrocatalysts for the C-C bond cleavage are essential to promote EOR with high effici...The application of direct ethanol fuel cell(DEFC)has been bottlenecked by the sluggish ethanol oxidation reaction(EOR).Efficient electrocatalysts for the C-C bond cleavage are essential to promote EOR with high efficiency and C1 selectivity.Here,we prepared Rh-Cu alloy nano-dendrites(RhCu NDs)with abundant surface steps through controlled co-reduction,which exhibited significantly enhanced activity and C1 selectivity(0.47 m A cm_((ECSA))^(-2),472.4 mA mg_(Rh)^(-1),and 38.9%)than Rh NDs(0.32 mA cm((ECSA))-2,322.1 mA mgRh-1,and 21.4%)and commercially available Rh/C(0.18 mA cm_((ECSA))^(-2),265.4 mA mg_(Rh)^(-1),and 14.9%).Theoretical calculations and CO-stripping experiments revealed that alloying with Cu could modulate the surface electronic structures of Rh to resist CO-poisoning while strengthening ethanol adsorption.In situ Fourier transform infrared spectroscopy(FTIR)indicated that the surface steps on RhCu NDs further promoted the C-C bond cleavage to increase the C1 selectivity.Therefore,optimizing the surface geometric and electronic structures of nanocrystals by rational composition and morphology control can provide a promising strategy for developing practical DEFC devices.展开更多
In this study, hierarchical copper nano-dendrites （CuNDs） are fabricated via the electrodeposition method. The electrochemical behaviors of the as-obtained hierarchical CuNDs in 0.1 M NaOH aqueous solution are subse...In this study, hierarchical copper nano-dendrites （CuNDs） are fabricated via the electrodeposition method. The electrochemical behaviors of the as-obtained hierarchical CuNDs in 0.1 M NaOH aqueous solution are subsequently studied. The CuNDs experience a non-equilibritrm oxidation process when subjected to cyclic voltammetry （CV） measurements. The first oxidation peak O1 in CV is attributed to the formation of an epitaxial Cu20 layer over the surface of the hierarchical CuNDs. However, the second oxidation peak 02 in CV appears unusually broad across a wide potential range. In this region, the reaction process starts with the nucleation and growth of Cu（OH）2 nanoneedles, followed by the oxidation of Cu20. Upon the increase of potential Cu20 is gradually transformed to CuO and Cu（OH）2, forming a dual-layer structure with high productivity of Cu（OH）2 nanoneedles.展开更多
Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples w...Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM)and energy dispersive spectrometer(EDS),respectively.The results showed that molar ratio of the ethanol/distilled water is an important factor for formation of the different dendrite structures.There are different morphologies between tree-like SnO_(2) nanowhiskers and bunch of SnO_(2) nanorods.However,they are growing along the [112].展开更多
文摘The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique morphologies is crucial for enhancing the stability of PEMFCs.In this study,we synthesized a novel PtCu nano-dendrite(PtCuND)catalyst through a facile,one-step solvothermal process.The sub-nanometer particles and nanopores within this catalyst facilitate enhanced mass transport.In PEM single-cell tests,the PtCuND catalyst displays high activity and robust stability,achieving a mass activity of 0.65 A mgPt^(–1).Notably,after accelerated durability tests,the mass activity and the voltage at 0.8 A cm^(–2)of PtCuND exhibits only minimal decreases of 18.5%and 9 mV,respectively.The combined experimental results and theoretical calculations conclusively illustrate the optimized adsorption of oxygen species and the impact of compressive strain on the catalyst surface.The enhanced durability can be attributed to the maintained nano-dendritic morphology and the strengthened interaction within the Pt-Cu bonds.This work not only enhances the stability of PEMFCs but also provides a robust foundation for the future scaling up of catalyst production,paving the way for widespread application in sustainable energy systems.
基金the financial support from the National Natural Science Foundation of China(Nos.21971012,21922502,21971017)the National Key Research and Development Program of China(No.2020YFB1506300)+1 种基金the Beijing Municipal Natural Science Foundation(No.JQ20007)the Beijing Institute of Technology Research Fund Program。
文摘The application of direct ethanol fuel cell(DEFC)has been bottlenecked by the sluggish ethanol oxidation reaction(EOR).Efficient electrocatalysts for the C-C bond cleavage are essential to promote EOR with high efficiency and C1 selectivity.Here,we prepared Rh-Cu alloy nano-dendrites(RhCu NDs)with abundant surface steps through controlled co-reduction,which exhibited significantly enhanced activity and C1 selectivity(0.47 m A cm_((ECSA))^(-2),472.4 mA mg_(Rh)^(-1),and 38.9%)than Rh NDs(0.32 mA cm((ECSA))-2,322.1 mA mgRh-1,and 21.4%)and commercially available Rh/C(0.18 mA cm_((ECSA))^(-2),265.4 mA mg_(Rh)^(-1),and 14.9%).Theoretical calculations and CO-stripping experiments revealed that alloying with Cu could modulate the surface electronic structures of Rh to resist CO-poisoning while strengthening ethanol adsorption.In situ Fourier transform infrared spectroscopy(FTIR)indicated that the surface steps on RhCu NDs further promoted the C-C bond cleavage to increase the C1 selectivity.Therefore,optimizing the surface geometric and electronic structures of nanocrystals by rational composition and morphology control can provide a promising strategy for developing practical DEFC devices.
文摘In this study, hierarchical copper nano-dendrites （CuNDs） are fabricated via the electrodeposition method. The electrochemical behaviors of the as-obtained hierarchical CuNDs in 0.1 M NaOH aqueous solution are subsequently studied. The CuNDs experience a non-equilibritrm oxidation process when subjected to cyclic voltammetry （CV） measurements. The first oxidation peak O1 in CV is attributed to the formation of an epitaxial Cu20 layer over the surface of the hierarchical CuNDs. However, the second oxidation peak 02 in CV appears unusually broad across a wide potential range. In this region, the reaction process starts with the nucleation and growth of Cu（OH）2 nanoneedles, followed by the oxidation of Cu20. Upon the increase of potential Cu20 is gradually transformed to CuO and Cu（OH）2, forming a dual-layer structure with high productivity of Cu（OH）2 nanoneedles.
基金supported by grants from the Program of Science and Technology Bureau of Qingdao(NO.08-1-3-14-JCH).
文摘Tree-like SnO_(2) nanodendrites in large amounts have been prepared through two-step reactions.The nanoparticles used as the precursors have taken aggrega-tion forming tree-like or string of nanodendrtie.The samples were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),high-resolution transmission electron microscopy(HRTEM)and energy dispersive spectrometer(EDS),respectively.The results showed that molar ratio of the ethanol/distilled water is an important factor for formation of the different dendrite structures.There are different morphologies between tree-like SnO_(2) nanowhiskers and bunch of SnO_(2) nanorods.However,they are growing along the [112].
