NiFeLDH/Mo4/3B2−xTz/NF composite electrodes to enhance oxygen evolution performance

Abstract

A NiFeLDH/Mo_4/3B_2−xT_z/NF (nickel foam) composite electrode was prepared by electrodepositing a layer of NiFe-layered hydroxides (NiFeLDHs) on Mo_4/3B_2−xT_z/NF, which was obtained by soaking NF in two-dimensional Mo_4/3B_2−xT_z suspensions. The electrode enhances the electrocatalytic oxygen evolution reaction with overpotentials of 200 and 255 mV at current densities of 10 and 100 mA cm⁻², respectively, in 1.0 M KOH solution, while displaying excellent electrochemical stability. It is superior to commercial RuO₂ with overpotentials of 280 and 320 mV at current densities of 10 and 100 mA cm⁻², respectively. Density functional theory calculation shows that the electronic density of the composite materials increased after NiFeLDH was loaded on Mo_4/3B_2−xT_z and that the free energy change of the final velocity step of NiFeLDH/Mo_4/3B_2−xT_z/NF is clearly lower than that of Mo_4/3B_2−xT_z/NF for the oxygen evolution reaction; therefore, the activity of the former is higher than that of the latter, and this performance enhancement is attributed to the synergistic effect of Mo_4/3B_2−xT_z and NiFeLDH.