Carbon-Encapsulated Ruthenium Catalyst Enables Low-Energy Hydrogen Production with Simultaneous Wastewater Treatment

A research team from Gyeongsang National University has developed a pulsed-laser-fabricated ruthenium@carbon catalyst that significantly enhances the efficiency of hydrazine-assisted hydrogen production. Published 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, enabling large hydrogen yields at exceptionally low voltages while simultaneously degrading toxic hydrazine.

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 confirmed the fcc-structured metallic Ru core and the enhanced ordering of the carbon shell at higher laser energies. In situ analyses revealed that metallic Ru sites are responsible for hydrogen evolution, whereas surface-generated RuOOH species drive hydrazine oxidation. The complete study is available at https://doi.org/10.1016/j.esci.2025.100408.

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. 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. 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.

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. The findings highlight a promising strategy to combine green energy generation with pollutant removal using a single multifunctional electrocatalyst, potentially transforming how industries approach both energy production and wastewater management.