Hollow PtCo alloy nanostructures for efficient oxygen reduction electrocatalysis in polymer electrolyte membrane fuel cells

Abstract

Achieving an efficient oxygen reduction reaction (ORR) is of prime importance for fuel cell commercialization. Herein, a hollow nanostructure of PtCo alloy with an average particle size of only ∼5 nm was prepared through a simplistic ambient oxygen-involved surface engineering strategy. The electrochemical evaluation of the catalyst confirmed an initial mass activity (MA) of 0.56 and 0.48 A mg_Pt⁻¹ at 0.9 V based on the rotating disk electrode and membrane electrode assembly test, respectively, thus successfully breaking the previous perceptions of a very huge gap between the half- and full-cell MA. After 30 000 cycles of the accelerated stress test, the catalyst demonstrated durable cathodic reaction in fuel cells, satisfying the stability standards of the US Department of Energy. We discovered that efficient ORR electrocatalysis originates from optimized surface strain and favorable coordination environments of the designed catalyst.