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. In this work, we reveal by combining theoretical and experimental results that the activity enhancement in intermetallic structures for oxygen reduction reaction (ORR) originates from the intensified ligand effect. We prepared well-defined model nanocatalysts via confined nanospace-directed synthesis using mesoporous silica templates, which allows precise control over the size and shape of nanostructures. Importantly, this method can transform disordered alloy nanostructures into intermetallic analogues without agglomeration, enabling decoupling of an atomic ordering effect in catalysis. The prepared ordered intermetallic Pt3Co nanowires (O-PtCo NWs) can benefit from the intensified ligand effect, Pt-skin layer, and aggregation-tolerant contiguous structure, which lead to their superior ORR activity and durability to disordered alloy Pt3Co nanowires (D-PtCo NWs) and Pt/C catalysts. The multifunctionality of O-PtCo NWs is demonstrated with their higher activity and durability in alkaline hydrogen evolution reaction and acidic methanol oxidation reaction than D-PtCo NWs and Pt/C catalysts. Furthermore, the O-PtCo NWs-based cathode in proton exchange membrane fuel cell (PEMFC) shows much better durability than a Pt/C-based PEMFC.