Boosting Electrocatalytic Performance of NiFe Layered Double Hydroxides by Exposing High Active Edge Plane (012) for Oxygen Evolution Reaction
The instinct activity of NiFe layer double hydroxides (LDHs) for oxygen evolution reaction (OER) suffers from its predominately exposed basal plane (003), which was thought to be poor-activity. Herein, we construct a hierarchal structure of NiFe LDHs nanosheet-arrays-on-microplates (NiFe NSAs-MPs), to excavate the electrocatalytic activity of NiFe LDHs for OER by exposing high active plane, such as edge plane (012). It is surprising that the NiFe NSAs-MPs shows the activity of 100 mA/cm2 at the overpotential (η) of 250 mV, which is 5 times higher than that of (003) plane-dominated NiFe LDHs microsheet arrays (NiFe MSAs) at the same η, representing the excellent electrocatalytic activity for OER in alkaline media. Besides, we analyze OER activities of basal plane (003) and edge planes (012) and (110) of NiFe LDHs by density functional theory with on-site Coulomb interactions (DFT+U), and the calculation results indicate that the edge plane (012) exhibits the best catalytic performance among the various crystal planes because of the oxygen-coordination of Fe site, which is responsible for high catalytic activity of NiFe NSAs-MPs.