Hierarchical C–MoCS_x @MoS₂ nanoreactor as a chainmail catalyst for seawater splitting

Hierarchical structures with a complex interior and a functional exterior are highly advantageous for energy-related electrocatalysis. Herein, a carbon-supported molybdenum carbide/sulfide heterostructure interior is covered with a defect-rich MoS₂ nanosheet exterior. The resulting hierarchical structure (C–MoCS_x @MoS₂) is a promising nanoreactor for seawater splitting. X-ray absorption spectroscopy demonstrates that MoC and MoS₂ are chemically integrated into the C–MoCS_x core, providing abundant C–Mo–S sites for hydrogen evolution. Experimental studies and theoretical calculations show that the defect-rich MoS₂ exterior exhibits a high capability for repelling salt deposition, allowing the penetration of low-saline water into the inner C–MoCS_x to accelerate the water-splitting reaction. As expected, the obtained C–MoCS_x @MoS₂ is remarkably active and exceptionally stable in natural seawater. This work opens new avenues for developing effective electrocatalysts for seawater splitting and other energy-related applications.