Amorphous NiFe-layered double hydroxides nanosheets for oxygen evolution reaction

Abstract

The exposed active sites of NiFe layered double hydroxide (NiFe-LDH) for oxygen evolution reaction (OER) are limited by the compact packing of its two-dimensional lamella. In this work, amorphous NiFe-LDH (A-NiFe-LDH) with abundant active sites are synthesized by using Ni(II) nitrilotriacetate complex anion ([NTANi]−) as morphological control agent, which can expose more active sites of NiFe-LDH by controlling crystalline phase and grain size of NiFe-LDH. Structural characterization demonstrates that [NTANi]− is adsorbed on the surface of A-NiFe-LDH and confirms A-NiFe-LDH is amorphous. The electrocatalytic activity of A-NiFe-LDH for OER is much higher than that of both RuO2 and pristine NiFe-LDH. A-NiFe-LDH has low OER overpotential of 241 mV at 10 mV cm−2 and a small Tafel slope of 55 mV dec−1. The high electrocatalytic activity of A-NiFe-LDH could be attributed to its amorphous structure.