Synchronous interlayer and surface engineering of NiFe layered double hydroxides by functional ligands for boosting oxygen evolution reaction

NiFe layered double hydroxides (LDHs) are among the most advanced electrocatalysts for oxygen evolution reaction (OER), but their catalytic activity and long-term working stability still need to be highly boosted for practical applications. Herein, an innovative strategy that combines anion intercalation/deintercalation and surface coordination is developed, which simultaneously realizes the modification of the interlay and surface properties of the NiFe LDHs by ethylenediaminetetraacetate (EDTA) and trisodium citrate (TSC). The intercalation/deintercalation of the anions engineers the interlay structure, while the surface metal-ligand coordination tunes the surface properties. Both the EDTA- and TSC-engineered NiFe LDHs exhibit highly enhanced catalytic performance, showing an overpotential of 204 and 233 mV, respectively at 10 mA cm-2 in 1.0 M KOH. The remarkable catalytic performance of the EDTA-engineered NiFe LDHs is due to the combined effect of the intercalation/deintercalation and the surface metal-EDTA coordination, while the surface TSC coordination only shows limited promoting effect on catalytic activity. In addition, the EDTA-engineered NiFe LDHs demonstrate good working stability at 100 mA cm-2.