Enhanced Multifunctional Electrocatalytic Activity of Pt-Co Nanoalloy-Decorated Graphene Oxide Sheets through Strong Metal–Support Interaction

Abstract

Presently, minimizing the usage and boosting the electrocatalytic efficiency of the otherwise costly platinum group-based materials appear to be the only practical option for commercial utilization of electrochemical energy conversion devices. To this end, exploring the suitability of multifunctional catalyst materials could be a promising strategy. In this regard, combining the different functionalities like hybrids of inorganic and organic materials could be a potential approach. However, a comprehensive mechanistic understanding about the role of composition to the catalytically active sites in multifunctional electrocatalysts is crucial for the design of suitably active and durable electrocatalysts for these devices. To address this, we attempted to explore and understand the combined effect of alloying and graphene oxide (GO) support interactions over the electrocatalytic activity of Pt-Co/rGO electrocatalysts. For this, Pt-Co/rGO nanoalloys with varying Pt:Co ratios were prepared via simple hydrothermal treatment and tested for three important fuel cell reactions viz. oxygen reduction, methanol oxidation, and hydrogen evolution reactions. Among the so-crafted and electrocatalytically explored Pt:Co compositions viz. 1:1, 1:3, and 3:1 (with and without GO), the GO composite with a Pt:Co molar ratio of 1:1, i.e., Pt1Co1/rGO demonstrated the best electrocatalytic activity and durability for long-term electrolysis. The significantly enhanced multifunctional catalytic activity and stability of the crafted catalysts are attributed to the synergism between Pt-Co nanoalloys and rGO support that modifies the d-band electronic structure of Pt via ‘strong metal–support interaction’ and to the lattice strain induced by nanoalloying of Pt with Co.