2 research outputs found
Potential-Controlled Current Responses from Staircase to Blip in Single Pt Nanoparticle Collisions on a Ni Ultramicroelectrode
Collisions of electrocatalytic platinum
(Pt) single nanoparticles
(NPs) with a less electrocatalytic nickel (Ni) ultramicroelectrode
(UME) surface were detected by amplification of the current by electrocatalysis
of NPs. Two typical types of current responses, a current staircase
or blip (or spike), in single NP collision experiments were observed
at a time with a new system consisting of Pt NP/Ni UME/hydrazine oxidation.
The staircase current response was obtained when the collided NPs
were attached to the electrode and continued to produce electrocatalytic
current. On the other hand, the blip current response was believed
to be obtained when the NP attached but was deactivated. The different
current responses depend on the different electrocatalytic reaction
mechanism, characteristics of the NP, or the electrode material. How
the deactivation of the electrocatalytic process affects on the current
response of NP collision was investigated using the Ni UME. The current
response of a single Pt NP collision is controllable from staircase
to blip by changing the applied potential. The current response of
the Pt NP was observed as a staircase response with 0 V (vs Ag/AgCl)
and as a blip response with 0.1 V (vs Ag/AgCl) applied to the Ni UME
Enhanced Hydrogen-Storage Capacity and Structural Stability of an Organic Clathrate Structure with Fullerene (C<sub>60</sub>) Guests and Lithium Doping
An
effective combination of host and guest molecules in a framework
type of architecture can enhance the structural stability and physical
properties of clathrate compounds. We report here that an organic
clathrate compound consisting of a fullerene (C<sub>60</sub>) guest
and a hydroquinone (HQ) host framework shows enhanced hydrogen-storage
capacity and good structural stability under pressures and temperatures
up to 10 GPa and 438 K, respectively. This combined structure is formed
in the extended β-type HQ clathrate and admits 16 hydrogen molecules
per cage, leading to a volumetric hydrogen uptake of 49.5 g L<sup>–1</sup> at 77 K and 8 MPa, a value enhanced by 130% compared
to that associated with the β-type HQ clathrate. A close examination
according to density functional theory calculations and grand canonical
Monte Carlo simulations confirms the synergistic combination effect
of the guest–host molecules tailored for enhanced hydrogen
storage. Moreover, the model simulations demonstrate that the lithium-doped
HQ clathrates with C<sub>60</sub> guests reveal exceptionally high
hydrogen-storage capacities. These results provide a new playground
for additional fundamental studies of the structure–property
relationships and migration characteristics of small molecules in
nanostructured materials