Engineering PtFe/LiO2 Frontier Orbital Interaction in Li–O2 Batteries

Elucidating the structure–activity relationship between the electronic structure of catalytic active sites and oxygen evolution reaction (OER) activity at the orbital level is critical yet challenging in lithium–oxygen (Li–O 2 ) batteries. Herein, employing frontier molecular orbital theory, we designed a Pt-based catalyst as a model cathode to investigate the influence of frontier orbital interactions between the Pt d z 2 orbital and the 5 σ orbital of LiO 2 on the OER activity. Specifically, compared to the pure Pt catalyst, the d z 2 – d z 2 orbital coupling between low-electronegativity Fe and Pt in PtFe catalyst induces predominant electron transfer from Fe to the d z 2 frontier orbital of Pt. As the Pt content in PtFe alloys increases progressively (from Pt 58 Fe 42 , Pt 67 Fe 33 to Pt 76 Fe 24 ), the electron population of the Pt 5 d z 2 orbital gradually decreases (1.92 for Pt 58 Fe 42 , 1.85 for Pt 67 Fe 33 , and 1.80 for Pt 76 Fe 24 ). This leads to a gradual enhancement in the strength of interactions between the Pt d z 2 orbital and the frontier orbitals of LiO 2 , consequently resulting in a progressive decline in the OER catalytic activity. Establishing the correlating between the electron population in the d z 2 frontier orbital and OER activity provides a descriptor for designing efficient electrocatalysts in Li–O 2 batteries.