Carbon-Shelled Ruthenium Spheres Power a Greener Route to Hydrogen and Wastewater Purification
Newswise — Hydrogen is expected to play a central role in future carbon-neutral energy systems, but conventional water electrolysis is hindered by the slow and energy-intensive oxygen evolution reaction. Replacing this step with hydrazine oxidation significantly reduces the voltage needed for hydrogen production, while converting hydrazine—an industrial pollutant—into harmless nitrogen. Yet hydrazine-assisted hydrogen systems depend on catalysts capable of driving both hydrogen evolution and hydrazine oxidation efficiently and stably. Achieving such performance requires precise control of catalyst composition, interface structure, and active-site distribution. Due to these challenges, it is necessary to conduct in-depth studies on high-performance bifunctional catalysts that can operate under low energy input.
A research team from Gyeongsang National University reports a pulsed-laser-fabricated ruthenium@carbon catalyst that significantly enhances the efficiency of hydrazine-assisted hydrogen production. Published (DOI: 10.1016/j.esci.2025.100408) in eScience on September, 2025, the study demonstrates how the optimized Ru@C-200 catalyst achieves ultralow overpotentials for both hydrogen evolution and hydrazine oxidation. The researchers further integrate the catalyst into a zinc–hydrazine battery and a hybrid hydrazine-splitting electrolyzer, enabling continuous self-powered hydrogen generation while simultaneously degrading hydrazine. Their work highlights a promising approach to coupling clean fuel generation with waste treatment.
The researchers synthesized the ruthenium@carbon material using a pulsed-laser ablation-in-liquid strategy that produced uniform Ru nanospheres encapsulated within graphitic carbon shells. Among all samples, Ru@C-200 displayed the most favorable balance of conductivity, structural stability, and electronically coupled metal–carbon interfaces. This optimized design enabled a low overpotential of 48 mV for hydrogen evolution and only 8 mV for hydrazine oxidation at 10 mA cm⁻², far outperforming conventional electrocatalysts.
Comprehensive characterization—including Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman Spectroscopy (Raman), X-ray Photoelectron Spectroscopy (XPS), and Extended X-ray Absorption Fine Structure (EXAFS)—confirmed the fcc-structured metallic Ru core and the enhanced ordering of the carbon shell at higher laser energies. In situ Raman and -ray Absorption Near-Edge Structure (XANES) analyses revealed that metallic Ru sites are responsible for hydrogen evolution, whereas surface-generated RuOOH species drive hydrazine oxidation.
When tested in a hydrazine-splitting electrolyzer, a Ru@C-200‖Ru@C-200 pair required only 0.11 V to achieve 10 mA cm⁻² and maintained stability for over 100 hours. The team further demonstrated a rechargeable Zn–hydrazine battery capable of powering hydrogen production independently. The battery achieved 90% energy efficiency and remained stable across 600 charge–discharge cycles. These results underscore how engineered Ru–C interfaces simultaneously improve activity, selectivity, and durability for both anodic and cathodic reactions.
According to the research team, the Ru@C-200 catalyst stands out for its rare combination of low energy consumption, long-term durability, and bifunctional catalytic capability. The expert emphasized that strong electronic coupling between the ruthenium core and carbon shell plays a pivotal role in accelerating charge transfer and efficiently activating hydrazine and hydrogen-related intermediates. They noted that this interface-engineered design demonstrates how a single multifunctional catalyst can address the dual needs of lowering hydrogen production costs and eliminating hazardous hydrazine pollutants, offering new possibilities for integrated clean-energy technologies.
The Ru@C-based catalytic system provides a compelling route for hydrogen production at voltages dramatically lower than those required for traditional electrolysis, offering substantial energy savings. Its ability to completely oxidize hydrazine while generating hydrogen positions it as a practical solution for industries that manage hydrazine-rich wastewater. The successful coupling with a rechargeable Zn–hydrazine battery illustrates a self-powered model in which hydrogen production, waste treatment, and energy storage occur simultaneously. This approach may accelerate the adoption of safer, more efficient hydrogen infrastructures and inspire new hydrazine-assisted technologies tailored for clean energy conversion and environmental remediation.
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Carbon-Shelled Ruthenium Spheres Power a Greener Route to Hydrogen and Wastewater Purification, source
