Metal nanostructures with an ultrathin Pt skin and abundant surface defects are attractive for electrocatalytic applications owing to the increased utilization efficiency of Pt atoms and the presence of highly reactive sites. This paper reports a conformal, layer-by-layer deposition of Pt atoms on defective Rh nanowires for the faithful replication of surface defects (i.e., grain boundaries) on the Rh nanowires. The thickness of the Pt shell can be controlled from one monolayer up to 5.3 atomic layers. This series of Rh@Pt nL (n = 1-5.3) core-sheath nanowires show greatly enhanced activity and durability in catalyzing the ethanol oxidation reaction in an acidic medium. Among others, the Rh @ Pt 3.5L nanowires show the greatest mass activity (809 mA mg −1 Pt ) and specific activity (1.18 mA cm −2 ) after loaded on carbon support, which are 3.7 and 3.4 times those of the commercial Pt/C, respectively. In situ Fourier transform infrared spectroscopy studies indicate an enhanced interaction between the outermost Pt layer and the Rh nanowire can promote CC bond cleavage for complete oxidation of ethanol to CO 2 while depress the dehydrogenation of ethanol to acetic acid. As the Pt shell thickness is increased, the selectivity for the CO 2 pathway decreases while that for acetic acid is increased.
Atomic
edge sites on two-dimensional (2D) nanomaterials display striking
catalytic behavior, whereas edge engineering for 2D metal nanocatalysts
remains an insurmountable challenge. Here we advance a one-pot synthesis
of ultrathin 2D PdPtCu trimetallic nanosheets and nanorings with escalating
low-coordinated edge proportions from 11.74% and 23.11% to 45.85%
as cutting-edge ethanol oxidation reaction (EOR) electrocatalysts.
This in situ edge enrichment hinges on a competitive surface capping
and etching strategy with integrated manipulation of the reaction
kinetics. Electrocatalysis tests demystify an edge-relied EOR performance,
where the edge-richest 9.0 nm-Pd61Pt22Cu17 nanorings attain an exceptional activity (12.42 A mg–1
Pt+Pd, 20.2 times that of commercial Pt/C)
with substantially improved durability. Molecularly mechanistic studies
certify that the unsaturated edge sites on these 2D catalysts prevail,
triggering the C–C bond scission and succeeding CO removal
to facilitate a 12-electron-transferring EOR process. This study introduces
the “metal-edge-driven” concept and enables the “edge
sites on 2D multimetallic nanocatalysts” technique to design
versatile heterocatalysts.
Atomically dispersed oxide‐on‐metal inverse nanocatalysts provide a blueprint to amplify the strong oxide–metal interactions for heterocatalysis but remain a grand challenge in fabrication. Here we report a 2D inverse nanocatalyst, RuOx‐on‐Pd nanosheets, by in situ creating atomically dispersed RuOx/Pd interfaces densely on ultrathin Pd nanosheets via a one‐pot synthesis. The product displays unexpected performance toward the oxygen reduction reaction (ORR) in alkaline medium, which represents 8.0‐ and 22.4‐fold enhancement in mass activity compared to the state‐of‐the‐art Pt/C and Pd/C catalysts, respectively, showcasing an excellent Pt‐alternative cathode electrocatalyst for fuel cells and metal–air batteries. Density functional theory calculations validate that the RuOx/Pd interface can accumulate partial charge from the 2D Pd host and subtly change the adsorption configuration of O2 to facilitate the O−O bond cleavage. Meanwhile, the d‐band center of Pd nanosubstrates is effectively downshifted, realizing weakened oxygen binding strength.
Orderly
assembled supernanosheets (ASNSs), integrating the architectural
features of subunit NSs, 2D subnanometer interlayer spacings, and
multiple electroactive sites, can remarkably expand the functionality
and stability of 2D multimetallic nanomaterials. Here, we report a
versatile template-directed strategy for synthesizing multimetallic
ASNSs. As a proof-of-concept, ternary Pd44Pt30Ir26 ASNSs are elaborately synthesized and applied as
robust bifunctional electrocatalysts toward overall water splitting.
The products are mesocrystalline 2D superstructures derived from lamellar
stacking of ultrathin Pd–Pt–Ir NSs. During electrocatalysis,
the multilayered superstructures can locally concentrate reactants
within the parallel subnanometer interlayer spacings and essentially
intensify the morphological stability. Featured with electronically
modulated Pt–IrO
x
dual active sites,
the products exhibit high efficiency and durable bifunctional electrocatalytic
activity for overall water splitting in 1.0 M KOH, presenting 46 and
92 mV lower overpotential than the state-of-the-art Pt/C and Ir/C
for hydrogen evolution and oxygen evolution reactions, respectively.
Significantly, they can realize stable H2 production at
a large current of 500 mA in an anion exchange membrane electrolyzer.
This work fully proves that the integration of an ordered 2D superstructure
and electronic-modulated multiple reactive sites has broad prospects
for advanced electrocatalysts.
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