Ultrasmall (<2 nm) Au@Pt Nanostructures: Tuning the Surface Electronic States for Electrocatalysis

Abstract

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.

Mesostructured cellular foam silica supported Au–Pt nanoalloy: Enrichment of d-state electrons for promoting the catalytic synergy

“…The upward shift of the s, p, d, f energy level revealed that more electrons in the corresponding energy level move close to the Fermi level. The high availability of electrons near the Fermi level is usually considered to enhance surface phenomena in heterogeneous catalysis [37]. The upward shift of energy level is in good accordance with the XPS and XANES results, indicating that more electrons are available on the surface of Au-Pt alloy NPs.…”

“…Moreover, the high availability of electrons near the Fermi level can enhance surface phenomena in heterogeneous catalysis [37]. Thus, the catalytic synergy on Au-Pt alloy NPs may be closely related to the available electrons near the Fermi level.…”

Reversing the charge transfer between platinum and sulfur-doped carbon support for electrocatalytic hydrogen evolution

“…Charge transfer, as a typical SMSI that occurs at the interface between metal nanoparticle and support, can introduce electronic modification on metal particles and directly influence their adsorption behavior during catalytic process, which will eventually change their catalytic reactivity and selectivity 4,5,12–15 . The importance of charge transfer and electronic perturbations on reactivity was manifested recently by Rodriguez and coworkers, in which Pt nanoparticles contacting with ceria support showed enhanced ability to dissociate O–H bonds in water and finally achieved the best catalytic activity at the greatest electronic perturbation 4 .…”

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible‐Light Illumination

“…Size decrease and shape control are effective ways to synthetically control the exposed catalytic Pt sites to give a high activity . Numerous Pt nanocrystals (NCs) with various shapes have been reported, and the size even decreases to single‐atom in electrocatalysis . Moreover, alloying Pt with other metals, such as Ni, Ag, Cu, Co, Pd, and Rh, is another effective strategy .…”