Research on preparation and OER properties of vanadium doped cobalt iron layered double hydroxide

Exploiting environmentally friendly and relatively low-toxicity oxygen evolution reaction (OER) electrocatalysts is currently one of the biggest difficulties in water splitting. In this work, cobalt iron layered double hydroxide (CoFe LDH) and vanadium-doped cobalt iron layered double hydroxide (V-CoFe LDH) nanosheets are in situ grown on nickel foam (NF) by electrodeposition as an effective OER catalyst. When CoFe LDH and V-CoFe LDH samples are used as electrocatalysts, they both exhibit excellent OER performance. In an alkaline media, when the current density is 100 mA·cm⁻², the overpotentials of CoFe LDH and V-CoFe LDH are small overpotentials of 396 mV and 356 mV, respectively. Tafel slopes of CoFe LDH and V-CoFe LDH are 224 mV·dec⁻¹ and 210 mV·dec⁻¹, respectively. The electrochemical activity specific surface area of V-CoFe LDH electrocatalysts is higher than CoFe LDH electrocatalysts. Moreover, the V-CoFe LDH electrocatalyst has better wetting properties for the electrolyte. These all indicate that the introduction of V helps to enhance the OER performance of the material. Density functional theory calculations and experimental results have shown that the doping of V not only optimizes the electronic structure of the material, enhances conductivity, but also reduces adsorption energy and enhances the contact between the catalyst and electrolyte. This work demonstrates that V-CoFe LDH is a highly promising OER electrocatalyst.