Surface-Engineered Ru–Graphene Mesosponge Catalysts for pH-Universal and Seawater Hydrogen Evolution

Efficient green hydrogen production from diverse water sources demands excellent catalysts that combine high activity, durability, and pH universality. Herein, we present a surface-engineered graphene mesosponge (GMS) uniformly decorated with ruthenium (Ru) nanoclusters as a robust electrocatalyst for the hydrogen evolution reaction (HER). The hierarchical GMS structure offers exceptional conductivity and mesoporosity, enabling nanoscale Ru dispersion and strong interfacial coupling. The obtained synergy of Ru50/GMS (optimized Ru deposition) delivers outstanding HER performance across pH range conditions, which provides overpotentials of ∼0.13 V and ∼0.061 V in acidic and alkaline electrolytes, respectively, close to those of the Pt electrode. Interestingly, Ru50/GMS achieves 10 mA cm–2 at only ∼0.39 V in neutral seawater, demonstrating robust operation under harsh, chloride-rich conditions. This performance is nearly 3-fold higher than that of pristine GMS, while sustaining accelerated kinetics and enhanced charge buffering. This is due to electronic modulation at the Ru–graphene interface via topological defects, which substantially optimized hydrogen adsorption and desorption, underpinning rapid reaction pathways. Furthermore, long-term operations confirm structural integrity and negligible catalyst degradation after 5000 cycles and 24 h at ultrahigh current density (−208 ± 10 mA cm–2), highlighting catalyst resilience for practical conditions. Therefore, this work demonstrates a scalable strategy for designing Ru-based catalysts on porous graphene supports, offering a compelling route for efficient, seawater-compatible green hydrogen production.