Korean researchers cut hydrogen production voltage to one-eighth with new catalyst

- Hongik University team develops catalyst combining platinum nanoclusters and amorphous oxide layer

- System maintains performance after 140 consecutive hours, with potential to treat industrial wastewater while producing hydrogen

A theoretical model and experimental implementation of a heterostructure catalyst based on a layered platinum selenide (PtSe₂) compound. [Provided by Hongik University]

South Korean researchers have developed a catalyst technology that can reduce the voltage required to produce hydrogen through water electrolysis to roughly one-eighth of what conventional methods demand. The technology is expected to enable simultaneous treatment of industrial wastewater containing the hazardous substance hydrazine and low-power hydrogen production.

The National Research Foundation of Korea announced Thursday that a research team led by Lee Won-gyu, a professor in the Department of Materials Science and Engineering at Hongik University, had developed a new water-electrolysis catalyst capable of low-power hydrogen production by treating a layered platinum selenide compound (PtSe₂) with oxygen plasma.

Hydrogen has drawn attention as a next-generation clean energy source because it emits no carbon during use. However, conventional water electrolysis has a significant drawback: the oxygen evolution reaction at the anode is slow and energy-intensive, requiring a high operating voltage.

To overcome this, the research team replaced the oxygen evolution reaction with a "hydrazine oxidation reaction" (HzOR). Hydrazine is a compound of nitrogen and hydrogen that releases nitrogen, hydrogen ions and electrons during oxidation. Because it can theoretically react at voltages close to 0V, it can dramatically reduce the energy needed for water electrolysis.

The challenge lies in the catalyst. Conventional platinum-based catalysts used for hydrazine oxidation suffer from reaction intermediates that adhere to the surface over time, gradually degrading performance. The high cost of platinum is also a barrier to commercialization.

The team found a solution by irradiating the surface of PtSe₂ — a material in which platinum and selenium are stacked in layers — with oxygen plasma. The plasma treatment produced a heterostructure on the material's surface in which an amorphous oxide layer and platinum nanoclusters coexist.

Lee Won-gyu, professor at Hongik University. [Provided by Hongik University]

In this structure, electrons transfer from the platinum clusters to the amorphous oxide layer, making it easier to break the nitrogen-hydrogen (N-H) bonds in hydrazine. Reaction intermediates on the catalyst surface are also removed more quickly, reducing the performance degradation seen in conventional platinum-based catalysts.

The team also built a "symmetric hydrazine-assisted water electrolysis system" by applying the same catalyst to both the anode and cathode. They succeeded in lowering the operating voltage to about one-eighth that of conventional oxygen-evolution-based water electrolysis. Performance was maintained even after 140 consecutive hours of operation, confirming long-term stability.

The technology has drawn particular attention for its potential to address industrial wastewater treatment and hydrogen production simultaneously. Rather than simply removing hydrazine from wastewater, using it as a reactant for hydrogen production yields two benefits at once: disposal of a hazardous substance and generation of energy.

However, hurdles remain before the technology can be applied in real industrial settings. Researchers must verify that catalyst performance holds up in actual wastewater, where hydrazine concentrations are low and various impurities are present. Safe handling systems for the toxic substance, long-term stability of the catalyst and membrane under high current density, reduced platinum usage, and large-area electrode manufacturing technology are also needed.

"Using oxygen plasma, we implemented a structure that can promote both reactions on a single PtSe₂ surface," Lee said. "Beyond improving the energy efficiency of hydrogen production, the approach could also be applied to a range of electrochemical reactions where catalyst activity declines due to intermediate adsorption."

The findings were published in Advanced Materials, an international journal in the field of materials science.

nbgkoo@heraldcorp.com