A NiCo-MOF nanosheet array based electrocatalyst for the oxygen evolution reaction

Abstract

Metal organic frameworks (MOFs) are excellent materials for energy storage and conversion. This report describes 2D metal–organic framework nanosheets as an electrocatalyst for the oxygen evolution reaction (OER) under alkaline conditions. An ultrathin nanosheet array of a NiCo-metal–organic framework was grown on nickel foam (NiCo-MOF/NF) by a one-step solvothermal method. The catalytic OER of the NiCO-MOF/NF electrode was analysed by electrochemical methods. The resulting NiCO-MOF/NF exhibited a high current density (50 mA cm⁻²) with an overpotential of 270 mV, a Tafel slope of 35.4 mV dec⁻¹ and a high turnover frequency (TOF) of 0.68 s⁻¹ (η = 0.27 V) towards the OER. The excellent catalytic activity of the MOF towards the OER was due to the two-dimensional nanosheet array of NiCo-MOF with plentiful accessible molecular active sites and excellent mass transport properties. Faster electron transport was also achieved due to the synergetic effect of Co and Ni present on the MOF.