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.

具有复杂内部和功能外部的分层结构对于与能量相关的电催化非常有利。在此，碳负载的碳化钼/硫化钼异质结构内部被富含缺陷的MoS ₂纳米片外部覆盖。由此产生的分层结构（C-MoCS _x @MoS ₂）是一种很有前途的用于海水分解的纳米反应器。X 射线吸收光谱表明 MoC 和 MoS ₂化学结合到 C-MoCS _x核心中，为析氢提供了丰富的 C-Mo-S 位点。实验研究和理论计算表明，富含缺陷的 MoS ₂外部表现出很高的排斥盐沉积的能力，允许低盐水渗透到内部 C-MoCS _x以加速水分解反应。正如预期的那样，所获得的 C-MoCS _x @MoS ₂在天然海水中非常活跃且异常稳定。这项工作为开发用于海水分解和其他能源相关应用的有效电催化剂开辟了新途径。