Small amount but big impact: Trace oxygen interstitially inserted PtCu alloys by microalloying for efficient oxygen reduction catalysis

The introduction of small size non-metal elements (e.g., oxygen) into solid solution alloys may be a promising strategy for fabricating efficient Pt-based catalysts with high activity and stability toward oxygen reduction reaction (ORR). Herein, oxygen interstitially inserted PtCu (O-PtCu) alloys are firstly designed by an oxygen-microalloying strategy, through ultraviolet (UV) irradiation-assisted galvanic replacement in an aqueous solution containing H₂PtCl₆ and Cu₂O nanowires as sacrificial templates. The obtained O-PtCu alloys feature a typical face-centered cubic (FCC) structure with majority Pt, Cu atoms as building bricks and trace interstitial oxygen (1.65 wt.%) existed in the octahedral sites surrounding Cu atoms, leading to a short-range disordered structure. The alloy reaches a recorded half-wave potential of 0.96 V (vs. reversible hydrogen electrode (RHE)) and mass activity of 0.48 A·mg_Pt⁻¹, much higher than those of commercial Pt/C. During the accelerated degradation test (ADT), the mass activity lost only 4.2% after 10k cycles, while the commercial Pt/C lost 66.7% under the same conditions. Compared with pure Pt and undoped PtCu alloy, the remarkably improved performance can be attributed to the lattice distortion and energy band reconstruction caused by the interstitial oxygen atoms in form of Cu–O bonds. Moreover, the stable Cu–O bonds delay the possible place exchange between surface Pt atoms and surface-adsorbed oxygen species, thereby hindering Pt dissolution, providing a new paradigm to address Pt degradation issue. Therefore, the introduction of interstitial oxygen into Pt-based alloys may be a facile and smart strategy for the development of advanced Pt-based alloys electrocatalysts.