Atomically Thin Defect-Rich Fe-Mn-O Hybrid Nanosheets as High Efficient Electrocatalyst for Water Oxidation

Engineering non-noble metal-based electrocatalysts with superior water oxidation performance is highly desirable for the production of renewable chemical fuels. Here, an atomically thin low-crystallinity Fe-Mn-O hybrid nanosheet grown on carbon cloth (Fe-Mn-O NS/CC) is successfully synthetized as an efficient oxygen evolution reaction (OER) catalyst. The synthesis strategy involves a facile reflux reaction and subsequent low-temperature calcination process, and the morphology and composition of hybrid nanosheets can be tailored conveniently. The defect-rich Fe-Mn-O ultrathin nanosheet with uniform element distribution enables exposure of more catalytic active sites; moreover, the atomic-scale synergistic action of Mn and Fe oxide contributes to an enhanced intrinsic catalytic activity. Therefore, the optimized Fe-Mn-O hybrid nanosheets, with lateral sizes of about 100-600 nm and approximate to 1.4 nm in thickness, enable a low onset potential of 1.46 V, low overpotential of 273 mV for current density of 10 mA cm(-2), a small Tafel slope of 63.9 mV dec(-1), and superior durability, which are superior to that of individual MnO2 and FeOOH electrode, and even outperforming most reported MnO2-based electrocatalysts.