CoNiFe alloy nanoparticles encapsulated into nitrogen-doped carbon nanotubes toward superior electrocatalytic overall water splitting in alkaline freshwater/seawater under large-current density.

This article focuses on the development and characterization of a bifunctional electrocatalyst, CoNiFe@NCNTs, composed of cobalt (Co), nickel (Ni), and iron (Fe) layered double hydroxide nanoflowers coated with nitrogen-doped carbon nanotubes (NCNTs), designed for efficient and durable overall water splitting. Synthesized via a corrosive approach followed by chemical vapor deposition using melamine, CoNiFe@NCNTs demonstrate enhanced electrocatalytic activity and stability for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline freshwater and seawater electrolytes, achieving low overpotentials and high current densities. The protective NCNT layer improves corrosion resistance and electron transfer, enabling stable operation at industrially relevant current densities, while the synergistic effects among the metal species optimize reaction kinetics. The catalyst's performance in seawater splitting addresses challenges related to chloride-induced corrosion, showing potential for sustainable hydrogen production from abundant seawater resources. This work contributes a promising, cost-effective alternative to precious metal catalysts for large-scale green hydrogen generation.