Ultrathin CoFe-Borate Layer Coated CoFe-Layered Double Hydroxide Nanosheets Array: A Non-Noble-Metal 3D Catalyst Electrode for Efficient and Durable Water Oxidation in Potassium Borate

It is highly desired to develop earth-abundant catalyst materials for efficient and durable water oxidation under benign conditions. In this Letter, we report on the development of ultrathin CoFe-borate layer coated CoFe-layered double hydroxide (LDH) nanosheets array supported on Ti mesh (CoFe-Bi@CoFe-LDH NA/TM) as a high-active 3D catalyst electrode at near-neutral pH for the oxygen evolution reaction (OER). In 0.1 M K2B4O7 solution (K-Bi, bulk pH: 9.2), such CoFe-Bi@CoFe-LDH NA/TM displays superior catalytic activity with small overpotential of 418 mV for 10 mA cm(-2). In addition, such catalyst electrode also exhibits superior long-period electrochemical activity and durability for OER and a relatively high turnover frequency (TOF) of 0.482 mol O-2 s(-1) achieved at overpotential of 600 mV.