Breaking the Local Symmetry of LiCoO2 via Atomic Doping for Efficient Oxygen Evolution.

Abstract

The obstacle for efficient electrochemical water splitting lies in the kinetically sluggish oxygen evolution reaction. Despite the various efforts that have been made to understand and tune the active sites for oxygen evolution reaction, an insight into the configurations of active sites from the electronic perspective is still lacking. Here, we report an atomic doping strategy to break the Oh symmetry of the CoO6 octahedron in LiCoO2. The specific activity of the La-doped LiCoO2 was 3.14 mA cm-2 at the overpotential of 0.35 V, which was 8.3 times higher than that of pristine LiCoO2. The overpotential with a value of 330 mV at 10 mA cm-2 was the lowest among the LiCoO2-based OER electrocatalysts ever reported. Mechanistic studies revealed that the superior activity originated from the asymmetric octahedral coordination of Co, resulting in the enhanced electronic conductivity and Co-O hybridization for the accelerated oxygen evolution kinetics. This work opens a door to enhance the catalytic performance through the manipulation of local symmetry.