Quenching modification of NiFe layered double hydroxides as efficient and highly stable electrocatalysts for the oxygen evolution reaction

Nickel- and iron-containing layered double hydroxides (NiFe-LDHs) are prospective electrocatalysts for the oxygen evolution reaction (OER), but they suffer from poor electrical conductivity and inaccessible active sites. Herein, we employ a facile and efficient quenching strategy to modify the morphology and surface characteristics of NiFe-LDHs by rapid cooling in a series of salt solutions. After quenching in a SnCl4 solution, the modified NiFe-LDHs exhibit a low overpotential of 204 mV at a current density of 10 mA center dot cm(-2) and Tafel slope of 58.0 mV center dot dec(-1) in a 1.0 M KOH solution. The improvement in the oxygen-evolution performance is ascribed to the morphology transformation from agglomerated NiFe-LDHs flowers into dispersed two-dimensional NiFe-LDHs nanosheets, which offers more active sites for the OER. Metal atoms are also introduced to the surface of NiFe-LDHs nanosheets during quenching, thereby changing the chemical coordination environment between Ni and Fe and improving their conductivity. Considering the diversity of LDHs and salt solutions, this quenching strategy may provide a sophisticated approach to preparing stable non-noble-metal electrocatalysts for the OER.