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.