Electron Tomography Analysis on the Structure and Chemical Composition of Nanoporous Metal Surfaces
Nanoporous metals have a porous structure with bicontinuous nanoscale voids and liga-ments.Thus,nanoporous metals differ from their bulk counterparts in mechanical,physical,and chemical characteristics due to their unique ligament structure and high surface-to-volume ratio.The surface struc-ture and chemistry of nanoporous metals play critical roles in their applications in catalysis,sensing,and other fields.The surfaces of nanoporous metals contain a substantial number of low-coordination sites,which are vital for improving their catalytic performance.Moreover,the addition of platinum to nanopo-rous gold has a massive impact on its catalytic and mechanical characteristics.High-resolution transmis-sion electron microscopy(TEM)and high-resolution scanning transmission electron microscopy(STEM)are commonly used to study the atomic structure of crystals.However,since these techniques only pro-vides two-dimensional projection images,it is usually hard or even impossible to directly and quantitative-ly resolve the three-dimensional(3D)structure of nanocrystals,especially their surface crystallography and coordination information.Compared to traditional TEM and STEM imaging technologies,electron to-mography with atomic resolution provides a powerful means to resolve 3D atomic-resolution information of materials.In this work,the surface structure and chemical composition of nanoporous gold and nano-porous gold-platinum were analyzed using STEM,electron tomography,and three-dimensional recon-struction of energy dispersive spectroscopy(EDS)results.The atomic structure of the ligament surface was examined using electron tomography with atomic resolution.It was observed that,surface defects can be separated into two categories:kinks and steps on the{111}terrace,and dents and pits.Surface dents and pits introduce a greater number of low-coordination sites than kinks and steps.Furthermore,the segregation of Pt on the ligament surface was discovered by combining the atomic-resolution elec-tron tomography with the 3D reconstruction of EDS results.
electron tomographyenergy dispersive spectroscopynanoporous matalsurface seg-regation
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维普
