In situ construction of CoFe-LDH by regulating the Co/Fe molar ratio for promoting oxygen evolution reaction

Corrosion technology is a simple method to synthesize oxygen evolution reaction (OER) electrocatalysts. Among many OER catalysts, transition metal layered double hydroxides (LDH) have attracted much attention due to their high activity and good stability. Here, an effective CoFe-LDH grown in-situ on Fe Foam (FF) has been prepared by corrosion technique with the assistance of NH4F. CFL-200 (CoFe-LDH synthesized with 200 mM NH4F) exhibits an excellent OER activity with an overpotential of 266 mV at 50 mA cm−2 and a Tafel slope of 35 mV dec−1. It also shows good stability over 100 h at 50 mA cm−2. The outstanding performance of CFL-200 can be attributed to the formation of nanosheet structure and the appropriate Co/Fe molar ratio which can be adjusted indirectly by NH4F. Combined with the corrosion method, this work provides a simple and efficient method to synthesize CoFe-LDH and modify its Co/Fe molar ratio to improve the activity.