NiFe layered double hydroxides synthesized based on solvent properties as anode catalysts for enhanced oxygen evolution reaction

Abstract

NiFe layered double hydroxides (LDH) with their high specific surface areas have been used as alternatives to noble metal catalysts for the oxygen evolution reaction (OER) in anion exchange membrane water electrolysis. However, for bulk LDH structures, relatively narrow interplanar distances can lead to the slow diffusion of OH− and the induction a local acidic atmosphere, resulting in catalyst corrosion. In this study, we synthesize solvent (water and ethanol) ratio-adjusted NiFe LDH anode catalysts to enhanced the OER. Results show that the catalyst prepared at a 5:5 ratio of water and ethanol (WE 55) delivers a low overpotential of 310 mV at 50 mA cm−2, Tafel slope of 40.5 mV dec−1, and 100 h-stability in a half-cell test, and a high current density of 744.2 mA cm−2 at 1.8 V and 70 °C in a single-cell test. WE 55 exhibits a manipulated oxygen vacancy and a substantially high specific surface area of ∼ 164.5 m2 g−1, leading to improved charge transfer and mass transport rates.