Characteristics of low-pressure-plasma-processed NiRu-MOFs/nickel foam for hydrogen evolution reaction

Abstract NiRu bimetallic metal–organic frameworks (NiRu-MOFs) are grown by a simple hydrothermal method on nickel foam (NF) as an the electrocatalyst for the hydrogen evolution reaction. Low-pressure plasmas of pure Ar, 95 %Ar + 5 %H2, and 95 % Ar + 5% O2 are used for the post-treatment of the NiRu-MOFs. NiRu-MOFs-AO with post-plasma treatment with 95 %Ar + 5 %O2 show the lowest overpotential of 123.3 mV at a current density of 10 mA/cm2 and a Tafel slope of 72.0 mV dec-1 in 1 M KOH electrolyte. Electrochemical impedance spectroscopy results indicate that post-plasma treatment can further reduce the charge transfer resistance. Moreover, the electric double-layer capacitance (Cdl) is calculated based on the cyclic voltammetry results, and the electrocatalyst subjected to 95 %Ar + 5 %O2 post-plasma treatment shows a 2Cdl value of 3.69 mF/cm2, suggesting a larger electrochemically active surface area after oxygen-containing-plasma treatment.