Researchers develop high-efficiency catalyst for hydrogen production from seawater

A joint research team from Gachon University, Ajou University and Kwangwoon University has developed an iron phosphide-carbon nanotube (FeP@CNT)-based bifunctional electrocatalyst capable of producing hydrogen from seawater at high efficiency while effectively suppressing chloride-induced corrosion, the universities announced Thursday.

The team was led by Kim Dae-geon and Ahn Yong-nam, professors in Gachon University's Department of Chemical Engineering, Life Sciences and Battery Engineering, along with Park Sung-jun of Ajou University and Lee Ki-won of Kwangwoon University.

The findings were published in Chemical Engineering Journal, an international peer-reviewed journal in environmental and chemical engineering with an impact factor of 12.5 and a ranking in the top 4 percent of its field.

The study's key achievements include the development of a highly durable electrolysis catalyst that works directly with seawater, a demonstration of low-driving-voltage green hydrogen production using solar cells, and long-term stability — sustaining hydrogen production for more than 1,000 hours under high-current conditions.

Green hydrogen production through water electrolysis has drawn attention as a core technology for the carbon-neutral era, as it can extract hydrogen by splitting water using renewable energy. However, using freshwater for large-scale hydrogen production places new pressure on water resources, making seawater electrolysis — which draws on the ocean's abundant supply — an attractive alternative. Seawater contains a wide range of ions, making the reaction environment considerably more demanding than conventional water electrolysis.

Chloride ions, present in large quantities in seawater, can adsorb onto electrode surfaces, corroding the catalyst or triggering side reactions that interfere with oxygen evolution. Achieving practical seawater electrolysis has therefore required a catalyst structure that simultaneously delivers high catalytic activity, the ability to block chloride ions and sustained performance over extended periods.

To address this challenge, the research team used metal-organic frameworks (MOFs) as a starting material to design the FeP@CNT heterostructure catalyst, in which iron phosphide (FeP) nanoparticles and carbon nanotubes (CNTs) are tightly integrated. Through a process called "PhosPy" — which carries out phosphorization and pyrolysis simultaneously — the team induced the formation of iron-based catalytic components alongside the in-situ growth of CNTs, resulting in a structure where active catalyst particles are stably anchored within a highly conductive carbon network.

Using density functional theory (DFT) calculations, the team found that a specific crystal face of Fe3P — one phase among several iron phosphide states — exhibits strong properties not only for hydrogen adsorption but also for water molecule adsorption, the first step in water electrolysis.

The iron phosphide provides active sites that promote the water-splitting reaction, while the surrounding carbon network serves both as a fast electron-transport pathway and as an interfacial environment that selectively restricts chloride ions from reaching the catalyst surface.

As a result, the catalyst achieves low overpotential characteristics that allow it to run on low-voltage power sources such as solar cells or small batteries. The team demonstrated continuous seawater electrolysis for more than 1,000 hours by applying the catalyst to both the anode and cathode. Even under high-current conditions simulating real hydrogen production, performance degradation was minimal, confirming that the catalyst's structure and active sites remained stable after extended operation.

The team also confirmed sustained gas generation in outdoor experiments using solar and small power sources, suggesting the potential to scale the technology into a seawater hydrogen production system linked to renewable energy. The research was supported by the National Research Foundation of Korea.