Hierarchical C–MoCSx @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–MoCSx @MoS2) is a promising nanoreactor for seawater splitting. X-ray absorption spectroscopy demonstrates that MoC and MoS2 are chemically integrated into the C–MoCSx 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–MoCSx to accelerate the water-splitting reaction. As expected, the obtained C–MoCSx @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.