Surface-selenization formed NiFe MOF@NiSex heterogeneous arrays for enhanced oxygen evolution and methanol electrooxidation

Abstract

Designing reasonable electrocatalysts for oxygen evolution reaction (OER) is a vital issue for water splitting to hydrogen. We report a surface-selenization of NiFe MOF-74 formed NiFe MOF@NiSe_x arrays through the simple solvothermal method. The NiFe MOF@NiSe_x heterostructures greatly enhance the charge transfer and cooperativity of active sites and result in strong adsorption capacity for OH^– to strongly boost the OER and MOR process. The optimized electrode shows the highly efficient catalytic activity for OER with a low onset potential of 1.31 V vs. RHE and small Tafel slopes of 38.3 mV dec⁻¹ in alkaline media. And it shows the extremely low overpotential of 229 and 329 mV at 100 and 500 mA cm⁻². Moreover, its current density can reach more than 500 mA cm⁻² at the potentials of 1.645 V vs. RHE at 0.8 M methanol/1 M KOH electrolyte, and it shows very good long-term stability at large current density. This heterogeneous arrays electrocatalysts may play a positive role in energy conversion and storage process.