Stabilizing the Fe Species of Nickel-Iron Double Hydroxide via Chelating Asymmetric Aldehyde-Containing THB Ligand for Long-Lasting Water Oxidation

Nickel-iron layered double hydroxides (NiFe LDHs) are considered as promising substitutes for precious metals in oxygen evolution reaction (OER). However, most of the reported NiFe LDHs suffer from poor long-term stability because of the Fe loss during OER resulting in severe inactivation. Herein, a dynamically stable chelating interface through in situ transformation of asymmetric aldehyde-ligand (THB, 1,3,5-Tris(3'-hydroxy-4'-formylphenyl)-benzene) modified NiFe LDHs to anchor Fe and significantly enhance the OER stability is reported. The fabricated asymmetric aldehyde-containing ligand THB is capable of stimulating much more interfacial charge transfer from NiFe LDHs to the oxygen group of THB and accelerating the formation of highly valent active Fe species leading to the strong combination between Fe and ligand and the reduced activation energy barrier of the intermediate, respectively. The optimized aldehyde-ligand-chelated NiFe LDHs (NiFe LDH/THB) shows enhanced OER performance featuring an overpotential of 224 mV at 100 mA cm^-2 and robust stability for over 3860 h at 100 mA cm^-2 in a water splitting device maintaining a cell voltage of only 1.68 V, which paves a new avenue to improve the water electrolysis performance of non-noble metal catalysts.