1706962 (1 of 6)
2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
2D PdAg Alloy Nanodendrites for Enhanced Ethanol
Wenjing Huang, Xiaolin Kang, Cheng Xu, Junhua Zhou, Jun Deng, Yanguang Li,*
and Si Cheng*
X. L. Kang, C. Xu, Prof. S. Cheng
College of Chemistry
Chemical Engineering and Materials Science
Suzhou, Jiangsu 215123, China
W. J. Huang, J. H. Zhou, J. Deng, Prof. Y. G. Li
Institute of Functional Nano and Soft Materials (FUNSOM)
Jiangsu Key Laboratory for Carbon-Based Functional Materials
Suzhou, Jiangsu 215123, China
The ORCID identiﬁcation number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/adma.201706962.
the introduction of the second component
may signiﬁcantly modify the electronic
structure of Pd and consequently weaken
its afﬁnity for poisonous adspecies.
spite of some encouraging progress over
recent years, the improvement in dura-
bility is still unsatisfactory.
On the other hand, nanostructuring
of electrocatalysts represents another
effective strategy to expose surface active
sites and improve their electrochemical
2D metallic nanoden-
drites are a rare class of materials with
high structural anisotropy.
enlarged surface areas and abundant
undercoordinated sites, can provide a
natural framework for the investigations
of defective systems, and may hold unex-
pected promise for catalytic applications.
However, their formation condition is very
stringent and requires the thermodynami-
cally unfavorable and kinetically driven ramiﬁcation within
2D and at the same time suppressed crystal growth along the
normal direction. Particularly important is that the in-plane
growth rate should be sufﬁciently fast that it becomes diffusion
Insufﬁcient in-plane growth rate would instead
result in common 2D nanoplates or nanosheets. The concomi-
tance of expedited in-plane growth and suppressed out-of-plane
growth is difﬁcult to achieve unless with the assistance of
proper structural directing agents (surfactants) under well-reg-
As a result, the preparation of 2D metallic
nanodendrites is highly challenging and seldom reported in lit-
erature as far as we are aware.
In this study, we present the facile preparation of intriguing
2D PdAg alloy nanodendrites (PdAg NDs) in aqueous solution
under ambient conditions. The introduction of octadecyltri-
methylammonium chloride (OTAC) as the structure directing
agent is found to hold the decisive key to the formation of this
highly anisotropic structure. Thanks to the synergistic coupling
between the two alloy components and the advantageous nano-
structure, PdAg nanodendrites enable excellent electrocatalytic
activity and durability for EOR in alkaline solution.
2D PdAg NDs were synthesized from the simultaneous
reduction of H
by ascorbic acid in their
aqueous solution with the presence of OTAC at 20
C (see Exper-
imental Section for details). This reaction was rapid (completed
in minutes), mild (used no hazardous solvents or chemicals),
reproducible, and could be potentially scaled up to gram-scale.
The development of highly active and stable electrocatalysts for ethanol elec-
troxidation is of decisive importance to the successful commercialization of
direct ethanol fuel cells. Despite great efforts invested over the past decade,
their progress has been notably slower than expected. In this work, the facile
solution synthesis of 2D PdAg alloy nanodendrites as a high-performance
electrocatalyst is reported for ethanol electroxidation. The reaction is carried
out via the coreduction of Pd and Ag precursors in aqueous solution with the
presence of octadecyltrimethylammonium chloride as the structural directing
agent. Final products feature small thickness (5–7 nm) and random in-plane
branching with enlarged surface areas and abundant undercoordinated
sites. They exhibit enhanced electrocatalytic activity (large speciﬁc current
2600 mA mg
) and excellent operation stability (as revealed from both the
cycling and chronoamperometric tests) for ethanol electroxidation. Control
experiments show that the improvement comes from the combined elec-
tronic and structural effects.
Direct ethanol fuel cells are promising energy conversion
devices that operate based on the electroxidation of ethanol.
They potentially have large energy and power density, but fall
far short of expectation due to the lack of high-performance
Pd-based materials have been widely
investigated for ethanol oxidation reaction (EOR) in alkaline
solution and yet generally suffer from insufﬁcient activity and
poor durability as the result of their rapid poisoning by carbo-
naceous reaction intermediates and byproducts.
strategy to promote their durability is alloying Pd with other
metals, such as Ag, Co, Cu, Ru, or Sn.
It is suggested that
Adv. Mater. 2018, 30, 1706962