Design and Synthesis of Bimetallic Electrocatalyst with Multilayered Pt-Skin Surfaces

Abstract

Advancement in heterogeneous catalysis relies on the capability of altering material structures at the nanoscale, and that is particularly important for the development of highly active electrocatalysts with uncompromised durability. Here, we report the design and synthesis of a Pt-bimetallic catalyst with multilayered Pt-skin surface, which shows superior electrocatalytic performance for the oxygen reduction reaction (ORR). This novel structure was first established on thin film extended surfaces with tailored composition profiles and then implemented in nanocatalysts by organic solution synthesis. Electrochemical studies for the ORR demonstrated that after prolonged exposure to reaction conditions, the Pt-bimetallic catalyst with multilayered Pt-skin surface exhibited an improvement factor of more than 1 order of magnitude in activity versus conventional Pt catalysts. The substantially enhanced catalytic activity and durability indicate great potential for improving the material properties by fine-tuning of the nanoscale architecture.

Understanding the electrocatalysis of oxygen reduction on platinum and its alloys

“…25 Although some of these studies reported promising mass activitites, 173 they were not amongst the highest reported in the literature. 168,169,175 Presumably this was due to the large particle sizes tested. Moreover, we anticipate that the well defined morphologies could be challenging to stabilise over long time periods.…”

Balance of Nanostructure and Bimetallic Interactions in Pt Model Fuel Cell Catalysts: In Situ XAS and DFT Study

“…For transition metal catalysts, the effect of bimetallic interactions can be rationalized with a shift of the d-band center [1][2][3] that is induced by the lattice expansion or compression (strain effect) 4 and by orbital interactions between the two different metals (ligand effect). [4][5][6] The d-band shift corresponds to a change of the d occupancy and therefore directly affects the metal-adsorbate bond strength via the population of antibonding states. 3,4 Due to linear relationships between the d-band shift and adsorption strength of various intermediates, the ORR activity can be simply modeled by considering only one intermediate, e.g.…”

Oxygen Reduction Reaction Measurements on Platinum Electrocatalysts Utilizing Rotating Disk Electrode Technique

“…[78][79][80] A common factor in a majority of the TF-RDE studies for Pt/C catalysts encountered in the literature is the incorporation of Nafion ionomer either mixed in with the catalyst ink formulation or applied as a cap over the dried catalyst film on RDE disk. 6,[13][14][15]17,[48][49][50][51]61,62,69,[81][82][83][84] However, the ORR activity values that are measured with added Nafion represent a complex, poorly defined, and variable electrochemical interface that can be represented as "Pt/C | discontinuous Nafion film soaked in 0.1 M HClO 4 , free 0.1 M HClO 4 ". We use this notation to describe two parallel interfaces, Pt/C in contact with HClO 4 soaked Nafion and Pt/C directly in contact with free HClO 4 as shown in Fig.…”