Pt-Based Core–Shell Catalyst Architectures for Oxygen Fuel Cell Electrodes

Abstract

Pt-based core–shell nanoparticles have emerged as a promising generation of highly active electrocatalysts to accelerate the sluggish kinetics of oxygen reduction reaction (ORR) in fuel cell systems. Their electronic and structural properties can be easily tailored by modifying the Pt shell thickness, core composition, diameter, and shape; this results in significant improvements of activity and durability over state-of-the-art pure Pt catalysts. Prompted by the relevance of efficient and robust ORR catalysts for electrochemical energy conversion, this Perspective reviews several concepts and selected recent developments in the exploration of the structure and composition of core–shell nanoparticles. Addressing current achievements and challenges in the preparation as well as microscopic and spectroscopic characterization of core–shell nanocatalysts, a concise account of our understanding is provided on how the surface and subsurface structure of multimetallic core–shell nanoparticles affect their reactivity. Finally, perspectives for the large-scale implementation of core–shell catalysts in polymer exchange membrane fuel cells are discussed.

Pt Sub-Monolayer on Au: System Stability and Insights into Platinum Electrochemical Dissolution

“…One of the suggested mitigation strategies is the utilization of Pt@M (Pt -shell, M -core) core/shell ORR catalysts with M usually Pd, Au, Ir, and other noble metals or first-row transition metals, aiming at improved activity and stability while reducing Pt content at the same time. 7,8 Due to enhanced Pt mass-and surface-area-normalized activity, [9][10][11][12][13] typical loadings of Pt in such catalysts can be significantly lower than those traditionally employed in commercial Pt/C-based catalysts. At the same time catalysts are supposed to have superior stability based on accelerated degradation tests, typically performed under rather mild conditions in half-cell rotating disc electrode investigations.…”

Noble Metal-Based Nanocomposites for Fuel Cells

“…The catalytic properties of Pt based core-shell NCs have close relationship with the Pt shell thickness. The charge transfer between core and shell components changes the band structure of shell, thus influencing the catalytic performance [60]. The electronic and geometric properties of the top surface layer are affected by the core, and the influence decreases with the increased thickness of shell.…”

Synthesis of Metastable Au-Fe Alloy Using Ordered Nanoporous Silica as a Hard Template

“…The wet chemistry synthesized alloy nanomaterials are prone to phase segregation especially when the constituent metals are much different in reduction potentials: one of the metal precursors with a low reduction potential readily forms a core, on which the other metal precursor with a high reduction potential precipitates to develop core-shell structures [6]. Post-annealing of such as-prepared alloy nanomaterials can improve the compositional uniformity because of promoted atomic interdiffusion but often lead to uncontrollable broadening in the particle/pore-size distribution due to particle agglomeration [7,8].…”