posted on 2019-01-29, 00:00authored byLucas D. Germano, Valeria S. Marangoni, Naga V. V. Mogili, Leandro Seixas, Camila M. Maroneze
The
ability to tune the electronic properties of nanomaterials has played
a major role in the development of sustainable energy technologies.
Metallic nanocatalysts are at the forefront of these advances. Their
unique properties become even more interesting when we can control
the distribution of the electronic states in the nanostructure. Here,
we provide a comprehensive evaluation of the electronic surface states
in ultrasmall metallic nanostructures by combining experimental and
theoretical methods. The developed strategy allows the controlled
synthesis of bimetallic nanostructures in the core–shell configuration,
dispensing of the use of any surfactant or stabilizing agents, which
usually inactivate important surface phenomena. The synthesized ultrasmall
Au@Pt nanoarchitecture (∼1.8 nm) presents an enhanced performance
catalyzing the hydrogen evolution reaction. First-principles calculations
of projected and space-resolved local density of states of Au55@Pt92 (core–shell), Au55Pt92 (alloy), and Pt147 nanoparticles show a prominent
increase in the surface electronic states for the core–shell
bimetallic nanomaterial. It arises from a more-effective charge transfer
from gold to the surface platinum atoms in the core–shell configuration.
In pure Pt147 or Au55Pt92 alloy nanoparticles,
a great part of the electronic states near the Fermi level is buried
in the core atoms, disabling these states for catalytic applications.
The proposed experimental–theoretical approach may be useful
for the design of other systems composed of metallic nanoparticles
supported on distinct substrates, such as two-dimensional materials
and porous matrices. These nanomaterials find several applications
not only in heterogeneous catalysis but also in sensing and optoelectronic
devices.