For
the first time, synthesis of Pd–Ir aerogel is reported
in this manuscript. The Pd–Ir aerogel is synthesized using
the controlled assembly of nanoparticles (NPs) (Ir and Pd) during
the facile, surfactant-free, fast, and one-step gelation process in
an aqueous environment followed by CO
2
supercritical drying.
In this process, no chemical reagents are employed to induce the gelation,
and change of temperature is employed to create anisotropic electrostatic
repulsions between NPs. In addition, the kinetics and the type of
product are controlled by the change of temperature. The Pd–Ir
aerogel shows a three-dimensional (3D) architecture with a very high
porosity and an ultralow density (0.016 g cm
–3
).
The Pd–Ir aerogel is applied as an advanced 3D electrocatalyst
for the ethanol oxidation reaction (EOR) and offers a remarkable electrocatalytic
efficiency (5416.1 mA mg
Pd
–1
) in a basic
environment. The exceptional electrocatalytic activity and stability
of the resultant aerogel are attributed to two crucial reasons: (1)
unique structure of Pd–Ir aerogel and (2) synergistic effect
of Ir element. Micro- and mesopore characteristics provide a large
surface area, while macrospore characteristic guarantees accessibility
to active sites. Furthermore, the self-supporting character of the
Pd–Ir aerogel may hinder the degradation of durability observed
in carbon-based electrocatalysts due to corrosion of carbonaceous
support. Moreover, the Ir element as a co-metal in the structure of
Pd–Ir aerogel acts as a very efficient promotor in the EOR
and can change the electronic structure of Pd, which facilitates the
electrooxidation of EtOH in alkaline media.
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