South Korean researchers develop robust and cost-effective electrocatalyst to produce hydrogen from seawater

In South Korea, among hydrogen production methods, alkaline water electrolysis is efficient and environmentally friendly; however, its dependence on freshwater limits large-scale implementation. Seawater electrolysis offers a practical alternative by tapping Earth’s abundant water resources, but high chloride concentrations accelerate catalyst corrosion and reduce efficiency, posing significant challenges for sustainable hydrogen generation.

To address this, a research team at Chung-Ang University and at Qingdao University of Science and Technology developed a robust and cost-effective electrocatalyst capable of high-performance hydrogen evolution in saline environments.

They designed a ruthenium (Ru)-based catalyst that overcomes limitations of conventional platinum or Ru catalysts in alkaline and seawater electrolysis. They employed a g-C3N4-mediated pyrolysis strategy to synthesize nitrogen-doped carbon-supported Ru nanoclusters with a crystalline–amorphous heterostructure (a/c-Ru@NC). g-C3N4 serves as a nitrogen source and a scaffold that anchors Ru³⁺ ions through N-coordination sites. During pyrolysis, reductive gases released from g-C3N4 reduce Ru³⁺ in situ, while Ru–N bonding disrupts atomic order in the core, forming an amorphous Ru phase. Surface Ru atoms simultaneously crystallize, producing a stable crystalline–amorphous junction. This architecture ensures ultrafine Ru dispersion, electron-deficient active sites, and compressive lattice strain.

Electrochemical testing demonstrated outstanding HER performance. In 1.0 M KOH, a/c-Ru@NC exhibited an overpotential of just 15 mV at 10 mA cm⁻². Durability was confirmed with stable operation over 250 hours. Crucially, the catalyst exhibited exceptional chloride corrosion resistance with only 8 mV performance degradation and stable operation over 100 hours in simulated seawater, outperforming commercial Pt/C and Ru/C.

The study highlights several advantages. The a/c-Ru@NC synergistically combines abundant active sites with optimized electron transport. The nitrogen-doped carbon support prevents Ru oxidation and agglomeration. The overall design provides exceptional chloride-corrosion resistance. Together, these features enable cost-effective, scalable hydrogen production directly from seawater. This approach reduces reliance on freshwater and fossil fuels while supporting decarbonization across energy-intensive sectors.