Fast fabrication of ultrathin CoMn LDH nanoarray as flexible electrode for water oxidation

Abstract

Electrochemical water splitting is an efficient way for large-scale production of clean hydrogen fuel. However, high overpotential is required to catalyzing oxygen evolution reaction (OER). Here we fabricate self-supported CoMn-LDH nanosheets with a thickness of approximately 1.9 nm on carbon fiber cloth through electrodeposition method within 50 s. The self-supported, binder-free anodes exhibit excellent OER performance with an overpotential of 258 mV at 10 mA cm−2 in 0.1 M KOH solution, remarkably lower than those of Co and Mn single counterparts, and the-state-of-the-art IrO2 catalyst. Furthermore, self-supported, binder-free anodes exhibit robust stability for OER with a negligible current loss even at a high current density (>370 mA cm−2) over 15 h. Flexible and bendable measurements indicate no obvious degradation in the OER performance of the anode even as being bended to 180°. Moreover, the water electrolysis with the CoMn-LDH/CFC as anode and Pt/C/CFC as cathode only needs a cell voltage of 1.54 V to deliver the current density of 10 mA cm−2 in 0.1 M KOH solution. Our experimental results demonstrate that the electron interaction between Mn and Co, increased electrochemical active area and decreased charge-transfer resistance contribute to the enhancement of the optimized anode in OER performance.