Lithium Electrochemical Tuning Engineering in an Aqueous System of LiCoO2 for Enhanced Oxygen Evolution Activity

Abstract

LiCoO2 is a promising catalyst for oxygen evolution reaction (OER), yet its OER activity is still unsatisfactory. Here, the delithiated LiCoO2 nanoparticles (NLCO-x cycle) are prepared via a new lithium electrochemical tuning in an aqueous two-electrode system for promoting OER in alkaline solutions. As a result, quantitative deintercalation of Li+ can be achieved through an aqueous two-electrode system and the OER performance of NLCO-5 cycle is significantly improved over that of pristine LiCoO2, with a low overpotential of 365 mV at 10 mA cm−2, a small Tafel slope of 55 mV dec−1, and low charge transfer resistance. Performance improvement results from electrochemical delithiation tuning the electronic structure of LiCoO2. The Li+ deintercalation process is accompanied by the partial oxidation of Co3+ to Co4+ and the increase of oxygen vacancies, which is associated with the enhanced intrinsic activity of the catalyst. This work paves a simple avenue for reasonable design of effective oxygen electrocatalysts by electrochemical tuning in aqueous systems.