Bimetallic alloys in action: dynamic atomistic motifs for electrochemistry and catalysis

Abstract

Bimetallic alloys show great promise for applications in a wide range of technologies related to electrochemistry and heterogeneous catalysis. The alloyed nature of these materials supports the existence of surface phenomena and structural motifs not present in single-component materials. These novel features result in electrochemical and catalytic behaviors, requiring entirely new categories of explanations. In this perspective concrete examples are used to illustrate several of these chemical and structural features, which are unique to multi-component metal surfaces. The influence of the surface's structure and surroundings (e.g. adsorbates) on each other provides a common thread, with the emergence of dynamic surfaces as its terminus. In considering three model systems (PtRu, PtNi and AuPd), we discuss not only a selection of surface phenomena relevant to each, but also the implications of these alloy-related behaviors for the electrochemical and catalytic properties of each surface.

Revealing the nature of active sites in electrocatalysis

“…In particular, density functional theory (DFT) has provided deep insight into heterogeneous catalysis as a whole. 7 In situ experimental and computational studies concur that catalytic activities are dictated by the nature of the active sites, which strongly depends on the materials' composition [13][14][15][16][17][18][19][20][21][22] and surface structure, [23][24][25][26] and the electrolyte composition. [27][28][29][30][31] In this perspective, we analyze several fundamental issues related to the elucidation of the electrocatalysts' active centers and factors that modify their catalytic efficiency.…”

Disentangling Catalytic Activity at Terrace and Step Sites on Selectively Ru-Modified Well-Ordered Pt Surfaces Probed by CO Electro-oxidation

“…14 Besides electronic effects, it is well known that the attachment of foreign atoms to a substrate can also induce changes in the catalytic properties of the substrate, once different equilibrium positions are attained due to strains in lattice constant provoked by these foreign atoms, [16][17][18] in which both electronic and strain effects are expected to operate simultaneously. 19 The combined action of bifunctional mechanism and electronic effect has been proposed to explain the role of Pt-Ru during CO electro-oxidation, 13 but the bifunctional mechanism is still the predominant model to explain the behavior of such systems. 1,11,12,[20][21][22] The bifunctional mechanism requires that during CO electro-oxidation the limiting step reaction at low overpotentials is a bimolecular collision between neighboring Pt κ -(CO) and an activated Ru γ -(H2O) species at a threshold potential via a LangmuirHinshelwood mechanism, being the formation of the last species promoted on Ru domains.…”

Electrochemical Scanning Probe Microscopies in Electrocatalysis

“…There are a number of examples in heterogeneous catalysis and electrocatalysis, where the ensemble effects are important . For the ensemble effects, a true alloy surface is required containing atoms of more than one element.…”