Exploring the mechanism of the excellent catalytic activity of NiFe-layered double hydroxides in oxygen evolution reactions by modifying the iron content

Abstract

Layered double hydroxides are very promising catalysts for water splitting, in particular NiFe-layered double hydroxide, which has attracted significant attention due to its excellent catalytic activity in oxygen evolution reactions using alkaline electrolytes. In this work, samples with different molar ratios of Ni to Fe are prepared by a typical hydrothermal method to study the effect of iron on the catalytic properties of NiFe-layered double hydroxide. All the NiFe-layered double hydroxides exhibit much better oxygen evolution reaction activity than NiOOH, while increasing the iron content slightly affects the activity, which implies that only Fe ions at some specific site contribute to the oxygen evolution reaction activity. The NiFe-layered double hydroxide with a 4:1 molar ratio of Ni to Fe shows the best oxygen evolution reaction catalytic performance, and requires only an overpotential of 176 mV to afford a current of 10 mA cm−2 in 1.0 M KOH, and exhibits a much lower Tafel slope (51 mV dec−1). This work also studies the effect of iron on the electronic structure of nickel and reveals the mechanism behind the excellent oxygen evolution reaction catalytic properties of NiFe-layered double hydroxide.