Ultrathin two-dimensional cobalt-organic framework nanosheets for high-performance electrocatalytic oxygen evolution

Ultrathin two-dimensional cobalt-organic framework (Co-MOF) nanosheets [Co2(OH)2BDC, BDC = 1,4-benzenedicarboxylate] with good catalytic activity for the oxygen evolution reaction were synthesized by a simple surfactant-assisted hydrothermal method. The resulting material shows a low overpotential of 263 mV at 10 mA cm−2 and a Tafel slope of 74 mV dec−1 in 1.0 M KOH. The morphology and properties of the material before and after electrocatalysis did not change significantly over a long period of time and it maintained electrochemical stability for 12 000 s. The unsaturated CoII active center on the surface of the ultrathin two-dimensional cobalt-organic framework nanosheets enhances their oxygen evolution reaction performance. These results are significantly superior to most of the previously reported transition metal-organic framework or metal oxide electrocatalysts. We believe that the ultrathin two-dimensional metal-organic framework nanosheets synthesized by this simple process will be widely used in future energy conversion devices. © The Royal Society of Chemistry.