It is extremely challenging to controllably synthesize rare earth‐containing nanoalloys due to the ultralow standard reduction potential of rare earth metals. Here, a surface‐confined strategy to prepare ultrafine Pt‐rare earth nanoalloys on a series of N‐functionalized supports is reported. It proves that by surface N‐metal coordination, the metal cations of precursors are atomically dispersed on support, which greatly favors uniform nucleation and growth of particles upon reduction. Moreover, the moderate metal transfer barrier from N ensures particle growth in a confined region to form ultrafine nanoalloys. Using this method, ultrafine PtLa, PtY, and PtDy nanoalloys are prepared on N‐functionalized supports such as carbon, zeolite, and Al2O3. Notably, the PtLa nanoalloys on N‐functionalized zeolite show superior activity and durability for propane oxidation. The strategy is expected to provide guidelines for preparing highly efficient rare earth‐containing nanoalloys for catalysis applications.
Due to the surface inhomogeneity of the solid supports, direct growth of uniform bimetallic nanoparticles (NPs) with controllable structure and size thereon is particularly challenging. Herein, a surface-confinement strategy is reported to directly prepare ultrafine bimetallic PtM NPs (MFe, Cu, and Co) with structure of core-shell or intermetallic compounds on an N functionalized carbon support (NC). It is found that the N species of NC support can atomically disperse metal cations of precursors, which largely renders uniform nucleation and growth of bimetallic NPs and fine structure modulation of them. In another regard, metal transfer is confined to a narrow region on NC via N-mediation, hence greatly favoring localized particle growth and formation of ultrafine bimetallic NPs. Remarkably, the ultrafine 3.1 ± 0.7 nm intermetallic Pt 3 Fe NPs on NC displayed excellent catalytic activity and durability toward electrochemical hydrogen evolution reaction.
Mesoporous support-encapsulated fine-size metal nanoclusters
hold
great potential for catalytic applications by virtue of their high
reactivity and fast mass transport kinetics but suffer greatly from
particle aggregation and/or sintering, especially under high reaction
temperatures. Here, we report an inner surface-confinement strategy
to stabilize a variety of ultrafine metal nanoclusters (M = Pt, Pd,
Ni, and Ag) inside mesoporous silica supports. The strategy is based
on the selective N functionalization of the inner surface of mesopores,
which not only assures the direct growth of ultrafine metal nanoclusters
therein but also endows the active metal nanoclusters with excellent
thermal stability via N-metal coordination. Remarkably, the mesopore-encapsulated
N-coordinated Pt nanoclusters are particularly selective for making
α,β-unsaturated alcohol, benefiting from their energetically
favored reaction pathway for end-on binding α,β-unsaturated
aldehyde reactants and heterolytic dissociation of hydrogen. The synthetic
methodology is expected to provide new guidelines to improve the thermal
stability of mesopore-encapsulated metal nanoclusters for superb catalysis.
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