High-performance electrocatalyst of vanadium-iron bimetal organic(J)framework arrays on nickel foam for overall water splitting

The development of active,low-cost and durable bifunctional electrocatalysts toward both oxygen evolution reaction(OER)and hydro gen evolution react ion(HER)a re important for overall water splitting.Here,well-defined arrays of vanadium-iron bimetal organic frameworks(VFe-MOF)with controllable stoichiometry have been successfully prepared on nickel foam(NF).The as-fabricated VFe-MOF@NF electrode exhibits excellent electrocatalytic activity and durability for OER and HER in alkaline medium.The material’s overpotentials of 10 mA/cm^(2) are 246 mV for OER and 147 mV for HER,respectively.The electrolyzer made from the VFe-MOF@NF electrodes as both the cathode and anode in 1 mol/L KOH needs only a voltage of 1.61 V to reach a current density of 10 mA/cm^(2).The superior performance of VFeMOF@NF can be attributed to the morphological control and electronic regulation of the bimetals,that is,1)the exposure of the active sites at electrocatalyst/electrolyte interfaces due to the array structure;2)the synergistic effect of vanadium and iron metals on electro-catalyzing the overall water splitting.