Composition controllable fabrication of ultrathin 2D CoMn layered double hydroxides for highly efficient electrocatalytic oxygen evolution

Oxygen evolution reaction (OER) is an important half-cell reaction of water splitting. The OER involves a multiple proton-coupled electron transfer process, which leads to the sluggish kinetic reaction. Searching for highly efficient route to synthesize electrocatalysts for OER is significant for developing sustainable energy systems. Herein, the 2D ultrathin cobalt-manganese layered double hydroxides (CoMn-LDHs) nanosheets with a typical hydrotalcite structure are prepared by a specific reduction–oxidation method. Particularly, the Co8Mn2-LDH electrocatalyst exhibits the highest activity along with a large surface area of 276.9 m2/g among different Co/Mn ratios of the CoMn-LDHs. The as-prepared Co8Mn2-LDH shows an overpotential as low as 307 mV at the 10 mA/cm2 current density and a small Tafel slope of 86 mV/dec. The Co8Mn2-LDH still maintains a satisfactory durability after a long-term continuous measurement. Such excellent electrocatalytic performance may be attributed to the huge surface area and the unique layered structure, which will do favor to the charge transport between the interface of solution and catalyst. Therefore, the reduction–oxidation method provides a highly efficient route to synthesize LDHs for OER.