Operando Identification of Hydrangea-like and Amorphous Cobalt Oxyhydroxide Supported by Thin-Layer Copper for Oxygen Evolution Reaction
Hsueh-Yu Chen, Yu‐Chung Chang, Jyh‐Fu Lee, Chih‐Wen Pao, Hsin‐Chih Huang, Chen‐Hao Wang
Abstract
This work demonstrates the unique three-dimensional (3D) layered hydrangea-like structure of amorphous CoOOH, which is deposited on thin-layer copper and nickel foam (CoOOH/Cu/Ni foam), showing the high activity of the oxygen evolution reaction (OER) at an overpotential of 260 mV with a current density of 10 mA cm–2. The CoOOH/Cu/Ni foam durability test shows almost no decay after 1000 cycles. The cell using the CoOOH/Cu/Ni foam for water electrolysis demonstrates a very stable current density of about 110 mA cm–2 at the cell potential of 1.8 V during 100 h of operation. The operando XAS analysis is carried out to understand the OER mechanism of the CoOOH/Cu/Ni foam. The hydrangea-like and amorphous CoOOH of the CoOOH/Cu/Ni foam shows the potential-dependent deprotonation reaction during the OER, forming a highly active phase. The thin-layer Cu of the CoOOH/Cu/Ni foam increases the conductivity and adsorbs oxygen intermediates after the initial reaction at onset potential to positively affect the OER.