Interface-engineered hybrid electrocatalysts of Ti@holey-TiN/layered-double-hydroxides for efficient seawater electrolysis

Interface structures have received significant attention because of their profound influence on the catalytic activities of nanostructured materials. Although energy-functional hybrid materials have been researched, there are no reports on using Ti@holey TiN foam as a hybridization matrix for high-performance electrocatalysts in seawater. In addition, the impact of a defective buffer layer on interfacial electronic coupling and electrocatalytic activity needs to be systematically investigated. In this study, we develop an interface engineering route to explore high-performance hybrid electrocatalysts for seawater electrolysis by introducing holey TiN nanoplates as buffer layers on the surface of a Ti foam. Hierarchical hybrid electrocatalysts of Ti@holey-TiN/Ni-Fe-layered double hydroxide (LDH) are synthesized by the sequential oxidation-nitridation of a Ti foam, followed by the deposition of LDH. The obtained Ti@holey-TiN/LDH nanohybrids display an outstanding performance as an oxygen evolution electrocatalyst with small overpotentials of 240 and 250 mV at 100 mA cm⁻² in an aqueous 1 M KOH solution and simulated alkaline seawater electrolyte, respectively. In situ spectroscopic analysis confirms the merits of holey TiN buffer layers in reinforcing interfacial electronic coupling with deposited LDH species and immobilizing the stoichiometric LDH phase, resulting in an increase in reaction kinetics of the LDH phase during the oxygen evolution reaction. The benefits of the hierarchical porous hybrid structure on the catalytic activity of seawater electrocatalysis can be ascribed to the enhanced electrical connection between the LDH and Ti substrate, provision of many electrochemically active sites, promotion of charge/mass transfer kinetics, and improved hydroxide adsorption selectivity.