Directional Manipulation of Electron Transfer by Energy Level Engineering for Efficient Cathodic Oxygen Reduction.

Abstract

Electron transfer plays an important role in determining the energy conversion efficiency of energy devices. Nitrogen-coordinated single metal sites (M-N₄) materials as electrocatalysts have exhibited great potential in devices. However, there are still great difficulties in how to directionally manipulate electron transfer in M-N₄ catalysts for higher efficiency. Herein, we demonstrated the mechanism of electron transfer being affected by energy level structure based on classical iron phthalocyanine (FePc) molecule/carbon models and proposed an energy level engineering strategy to manipulate electron transfer, preparing high-performance ORR catalysts. Engineering molecular energy level via modulating FePc molecular structure with nitro induces a strong interfacial electronic coupling and efficient charge transfer from carbon to FePc-β-NO₂ molecule. Consequently, the assembled zinc-air battery exhibits ultrahigh performance which is superior to most of M-N₄ catalysts. Energy level engineering provides a universal approach for directionally manipulating electron transfer, bringing a new concept to design efficient and stable M-N₄ electrocatalyst.