Abstract
Precise control of the morphology, composition and structure of metal nanostructures not only effectively improves their catalytic activity and durability but also enhances their range of applications. In this work, bimetallic Au@Rh core–shell nanodendrites are synthesized by a facile one-pot hydrothermal method. Physical characterizations show that the dendritic Rh consists of two-dimensional (2D) ultrathin Rh nanoplates with a thickness of approximately 1.2 nm. For the first time, Au@Rh core–shell nanostructures are used as a catalyst for the hydrogen generation reaction from aqueous hydrazine solution (N2H4=N2+2H2, HGR-N2H4). Bimetallic Au@Rh core–shell nanodendrites exhibit improved catalytic activity and durability for the HGR-N2H4 compared with commercial Rh nanocrystals, which can be attributed to the atomically ultrathin structure of 2D Rh nanoplates and the interconnected structure of nanodendrites, respectively. Under light irradiation, bimetallic Au@Rh core–shell nanodendrites show light-enhanced catalytic activity for the HGR-N2H4, originating from the distinctive localized surface plasmon resonance of Au icosahedron cores.
Highlights
Bimetallic noble metal nanostructures have been used in a variety of important industrial applications, especially in heterogeneous catalysis.[1,2,3,4,5,6] The physical and chemical properties of bimetallic noble metal nanostructures depend on their chemical compositions and are related to their morphologies.[4,5,6,7,8,9] In general, bimetallic nanostructures display remarkably improved catalytic activity and selectivity compared with the corresponding monometallic nanocrystals due to the strong ensemble and ligand effects between the different components (that is, geometrical and electronic effects).[4,5,6,7,9] noble metal nanodendrites with branched arms are attracting tremendous attention for the catalytic applications due to their large surface area, unusual interconnected and porous structure and abundance of low-coordination atoms at steps and corners.[10,11] bimetallic noble metal nanodendrites have a broad variety of applications, ranging from organic synthesis to energy conversion.[12,13]Among various bimetallic nanostructures, Au-based core–shell-type noble metal nanostructures have been widely employed in various important heterogeneous catalytic reactions, especially in lightenhanced catalytic reactions, originating from the high mass activity of noble metal shells and the distinctive localized surface plasmon resonance (LSPR) of Au nanocrystal cores.[14,15,16,17] In most bimetallic core–shell nanodendrites, the metal shells consist of spherical nanocrystals.[5,18,19] Recently, the atomically thick noble metal nanoplates, an emerging star nanomaterial for the catalysis, have attracted more attention compared with the traditional zerodimensional noble metal nanocrystals, owing to the extremely high meal atom utilization and superior catalytic activity.[20,21,22,23,24,25,26] Obviously, bimetallic core–shell nanodendrites with atomically ultrathin nanoplate shells are expected to possess greatly improved catalytic activity
We demonstrated that bimetallic Au@Rh core–shell nanodendrites with a well-defined octahedral Au core and a dendritic Rh shell could be achieved by a facile one-pot hydrothermal method, using polyallylamine hydrochloride (Supplementary Scheme S1A) as a surfactant and diethylene glycol (Supplementary Scheme S1B) as a reductant
X-ray photoelectron spectroscopic (XPS) analysis shows that the Au/Rh atomic ratio is 8.4:91.6 (Supplementary Figure S2), which is much lower than the value obtained by energy-dispersive X-ray (EDX) analysis (Au/Rh = 66:34)
Summary
Bimetallic noble metal nanostructures have been used in a variety of important industrial applications, especially in heterogeneous catalysis.[1,2,3,4,5,6] The physical and chemical properties of bimetallic noble metal nanostructures depend on their chemical compositions and are related to their morphologies.[4,5,6,7,8,9] In general, bimetallic nanostructures display remarkably improved catalytic activity and selectivity compared with the corresponding monometallic nanocrystals due to the strong ensemble and ligand effects between the different components (that is, geometrical and electronic effects).[4,5,6,7,9] noble metal nanodendrites with branched arms are attracting tremendous attention for the catalytic applications due to their large surface area, unusual interconnected and porous structure and abundance of low-coordination atoms at steps and corners.[10,11] bimetallic noble metal nanodendrites have a broad variety of applications, ranging from organic synthesis to energy conversion.[12,13]Among various bimetallic nanostructures, Au-based core–shell-type noble metal nanostructures have been widely employed in various important heterogeneous catalytic reactions, especially in lightenhanced catalytic reactions, originating from the high mass activity of noble metal shells and the distinctive localized surface plasmon resonance (LSPR) of Au nanocrystal cores.[14,15,16,17] In most bimetallic core–shell nanodendrites, the metal shells consist of spherical nanocrystals.[5,18,19] Recently, the atomically thick noble metal nanoplates, an emerging star nanomaterial for the catalysis, have attracted more attention compared with the traditional zerodimensional noble metal nanocrystals, owing to the extremely high meal atom utilization and superior catalytic activity.[20,21,22,23,24,25,26] Obviously, bimetallic core–shell nanodendrites with atomically ultrathin nanoplate shells are expected to possess greatly improved catalytic activity. Bimetallic AuRh nanodendrites consisting of Au icosahedron cores and atomically ultrathin Rh nanoplate shells: synthesis and light-enhanced catalytic activity
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