Nickel–Iron\nLayered Double Hydroxides/Nickel\nSulfide Heterostructured Electrocatalysts on Surface-Modified Ti Foam\nfor the Oxygen Evolution Reaction

Electrochemical approaches for generating hydrogen from\nwater splitting\ncan be more promising if the challenges in the anodic oxygen evolution\nreaction (OER) can be harnessed. The interface heterostructure materials\noffer strong electronic coupling and appropriate charge transport\nat the interface regions, promoting accessible active sites to prompt\nkinetics and optimize the adsorption–desorption of active species.\nHerein, we have designed an efficient multi-interface-engineered Ni<sub>3</sub>Fe<sub>1</sub> LDH/Ni<sub>3</sub>S<sub>2</sub>/TW heterostructure\non in situ generated titanate web layers from the titanium foam. The\nsynergistic effects of the multi-interface heterostructure caused\nthe exposure of rich interfacial electronic coupling, fast reaction\nkinetics, and enhanced accessible site activity and site populations.\nThe as-prepared electrocatalyst demonstrates outstanding OER activity,\ndemanding a low overpotential of 220 mV at a high current density\nof 100 mA cm<sup>–2</sup>. Similarly, the designed Ni<sub>3</sub>Fe<sub>1</sub> LDH/Ni<sub>3</sub>S<sub>2</sub>/TW electrocatalyst\nexhibits a low Tafel slope of 43.2 mV dec<sup>–1</sup> and\nexcellent stability for 100 h of operation, suggesting rapid kinetics\nand good structural stability. Also, the electrocatalyst shows a low\noverpotential of 260 mV at 100 mA cm<sup>–2</sup> for HER activity.\nMoreover, the integrated electrocatalyst exhibits an incredible OER\nactivity in simulated seawater with an overpotential of 370 mV at\n100 mA cm<sup>–2</sup> and stability for 100 h of operation,\nindicating good OER selectivity. This work might benefit further fabricating\neffective and stable self-sustained electrocatalysts for water splitting\nin large-scale applications.