Pt-Based Intermetallic Nanostructures: Activity Origin and Multifunctionality for Efficient Electrocatalysis

Abstract

Pt-based intermetallic nanostructures have demonstrated superior electrocatalytic performances compared to random alloy structures. However, the origin of their enhanced catalytic properties remains elusive. Furthermore, a robust synthetic strategy for well-defined intermetallic nanostructures represents a challenge. Here, we reveal that the activity enhancement in intermetallic structures for oxygen reduction reaction (ORR) originates from the intensified ligand effect by combining theoretical and experimental results. We prepared well-defined model nanocatalysts via confined nanospace-directed synthesis using mesoporous silica templates, which allows precise control over the size and shape nanostructures. Importantly, this method can transform disordered alloy nanostructures into intermetallic analogs without agglomeration, enabling that the influence of the atomic ordering effect to be decoupled from other structural factors, such as size, shape, ECSA, composition, and crystal structure. The prepared ordered intermetallic Pt3Co nanowires (O-Pt3Co NWs) showed superior ORR activity and durability to disordered alloy Pt3Co nanowires (D-Pt3Co NWs), intermetallic Pt3Co nanoparticles supported on carbon, and Pt/C catalysts. The multifunctionality of O-Pt3Co NWs was demonstrated with their highly enhanced catalytic activity and durability in alkaline hydrogen evolution reaction and acidic methanol oxidation reaction, compared to D-Pt3Co NWs and Pt/C catalysts. Furthermore, the O-Pt3Co NWs-based cathode in proton exchange membrane fuel cell (PEMFC) showed much better performance than a Pt/C-based PEMFC in practical PEMFC driving conditions.