In situ evolution of surface Co2CrO4 to CoOOH/CrOOH by electrochemical method: Toward boosting electrocatalytic water oxidation

Developing non-noble-metal electrocatalyst with efficient and durable activity is a urgent task for addressing the sluggish reaction kinetics of electrochemical water oxidation. Structural evolution of the electrocatalyst is an important strategy for achieving enhanced performance. Herein, in situ evolution of surface Co2CrO4 to CoOOH/CrOOH (CoOOH/CrOOH-Co2CrO4) by an electrochemical method under alkaline conditions was designed for enhancing the electrocatalytic performance of water oxidation. The experiments demonstrated that the synergy between CoOOH/CrOOH and Co2CrO4 resulted in a marked increase in the number of active sites and improved the rate of charge transfer, which enhanced the activity for water oxidation. At a geometrical current density of 20 mA cm−2, the overpotential of the oxygen evolution reaction was 244 mV and the turnover frequency was 0.536 s−1 in 1.0 M NaOH.