The
design of Pt-based alloy nanocatalysts with sufficient accessible
surface areas and abundant active sites is important for their application
in direct methanol fuel cells (DMFCs) and direct ethanol fuel cells
(DEFCs). Here, we report a simple one-pot method for the preparation
of PtCuNi hexapod nanocrystals. The conversion mechanism of the nanoparticles
from rhombic dodecahedra to hexapods was investigated by time evolution
experiments. Electrochemical tests demonstrated that the PtCuNi nanohexapods
exhibited greatly elevated catalytic performance for methanol oxidation
reaction (MOR) and ethanol oxidation reaction (EOR) under acidic conditions.
Specifically, the PtCuNi nanohexapods have mass activities of 1.73
and 2.31 A mgPt
–1 for MOR and EOR, which
are 2.9 and 2.3 times higher than those of the commercial Pt/C catalyst,
respectively. Moreover, the PtCuNi nanohexapods also exhibit enhanced
electrocatalytic stability compared to Pt/C. This work provides an
effective strategy for the rational construction of nanocrystals with
desired morphologies and structures in the application of catalysis,
energy, sensors, and other fields.
Pt-based nanocrystals with a three-dimensional (3D) branched
structure
represent a class of the most efficient catalysts for the methanol
oxidation reaction because of their large accessible surfaces and
high atomic utilization. Herein, nanoscale PtCuMn hexapods (HPDs)
have been synthesized by a facile one-pot solvent method. Strikingly,
the as-synthesized HPDs each contain a rhombic dodecahedral host and
six nanopods protruding from its ⟨100⟩ vertices. Evolution
experiments demonstrate that four stages are responsible for formation
of the HPDs: the preferential formation of Cu-enriched nuclei, the
galvanic substitution reaction between Cu-enriched nuclei and a Pt
precursor, the selective growth of Pt, and the deposition of Pt, Cu,
and Mn. Moreover, the morphology of the HPDs can be tuned by adjusting
the dosage of cetyltrimethylammonium bromide because of its ability
to affect the size of the preformed Cu-enriched nuclei and the rate
of the galvanic substitution reaction during the synthesis. For methanol
electrocatalysis, the PtCuMn HPDs exhibit substantially enhanced electrocatalytic
activity and durability in comparison with the commercial Pt/C catalyst.
It is expected that this work may provide an idea for the facile synthesis
of Pt-based catalysts with high efficiency and stability.
Herein, we report a two-step strategy for the preparation of vertex-type-selectively reinforced PtCu@PtCu-Ni double-layered nanoframes (DNFs). In the first step, PtCuNi heterogeneous nanocrystals (HNCs) were synthesized by a facile one-pot solvent method. The PtCuNi HNC is composed of a Cu-enriched concave rhombic dodecahedral core, a double-layered nanoframe consisting of an inner vertexselectively-reinforced rhombic dodecahedral PtCu nanoframe and an outer concave rhombic dodecahedral PtCuNi nanoframe, and a Ni-enriched shell. In the second step, PtCu@Pt-CuNi DNFs were prepared by selectively removing the leachable components via acid treatment. Strikingly, the inner rhombic dodecahedral nanoframe contained six nanopods sticking out from its h100i vertices rather than h111i ones, and the outer concave rhombic dodecahedral nanoframe is formed by interconnecting the adjacent vertices of the inner nanoframe. The electrocatalytic test for methanol oxidation reaction showed that the as-prepared PtCu@PtCuNi DNFs exhibited enhanced electrocatalytic activity and improved stability compared to the commercial Pt/C catalyst.
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