Hierarchical NiFe Layered Double Hydroxide Hollow Microspheres with Highly-Efficient Behavior toward Oxygen Evolution Reaction.

The exploitation of highly efficiency and low-cost electrocatalysts toward oxygen evolution reaction (OER) is a meaningful route in renewable energy technologies including solar fuel and water splitting. Herein, NiFe-layered double hydroxide (NiFe-LDH) hollow microsphere (HMS) was designed and synthesized via a one-step in situ growth method by using SiO2 as a sacrificial template. Benefiting from the unique architecture, NiFe-LDH HMS shows highly efficient OER electrocatalytic activity with a preferable current density (71.69 mA cm-2 at η = 300 mV) and a small onset overpotential (239 mV at 10 mA cm-2), which outperforms the 20 wt % commercial Ir/C catalyst. Moreover, it exhibits a remarkably low Tafel slope (53 mV dec-1) as well as a satisfactory long-time stability. Electrochemical studies reveal that this hierarchical structure facilitates a full exposure of active sites and facile ion transport kinetics, accounting for the excellent performance. It is expected that the NiFe-LDH microsphere material can serve as a promising non-noble-metal-based electrocatalyst toward water oxidation reaction.