Turning seawater into green gold: innovative catalyst enables continuous hydrogen production and high-purity mineral recovery

As the global demand for sustainable energy rises, direct seawater electrolysis (DSE) has emerged as a vital technology for producing green hydrogen without the need for energy-intensive freshwater purification. However, a major hurdle has been "scaling"—the buildup of mineral deposits like magnesium hydroxide on the cathode, which quickly degrades performance.

In a news & highlight article published in the journal ENGINEERING Energy, researchers from Shandong University have highlighted a recent breakthrough of "charge-engineering" strategy reported in Nature Communications (DOI: 10.1038/s41467-025-66473-6) for natural seawater electrolysis. By modifying platinum (Pt) catalysts with halide ions, the teams of Professor Zhiyi Lu from Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences and Professor Xinlong Tian from Hainan University created a cathode that not only prevents scaling but also enables the recovery of high-purity magnesium hydroxide [Mg(OH)₂], a valuable byproduct for pharmaceutical and industrial use.

The Challenge of Cathode Scaling

While much research has focused on protecting anodes from seawater corrosion, the cathode faces its own set of problems. During the hydrogen evolution reaction (HER), the area near the cathode becomes highly alkaline. This causes magnesium (Mg²⁺) and calcium (Ca²⁺) ions in the seawater to form solid precipitates that coat the electrode, blocking active sites and increasing maintenance costs.

"Cathode fouling has received comparatively little attention in direct seawater electrolysis, yet it is a critical barrier to long-term stability," notes Professor Tianyi Kou, the corresponding author of this news & highlight article.

A "Repulsive" Solution to Mineral Buildup

The research teams of Professor Zhiyi Lu and Professor Xinlong Tian developed a novel strategy to anchor halide ligands—specifically fluoride, chloride, bromide, or iodide—onto the surface of Pt catalysts. The iodide-modified platinum (Pt-I) proved particularly effective.

The innovation works through two primary mechanisms:

• Electronic Modulation: The halide ligands adjust the electronic structure of the platinum, weakening the bond between the surface and hydrogen atoms (*H), which accelerates the hydrogen production process.
• Like-Charge Repulsion: The modified surface is electron-rich and carries a negative charge. This creates a "like-charge repulsion" that pushes negatively charged hydroxyl ions (OH⁻) away from the electrode surface and into the bulk liquid.

By shifting the high-pH region away from the electrode, the minerals form as pure particles in the liquid rather than a crust on the catalyst.

High Stability and Commercial Value

The results of the Pt-I electrode are significant. In long-term stability tests conducted at 100 mA cm⁻² in natural seawater, the cathode operated for 5,000 hours with almost no decay in performance. Furthermore, the system precisely controlled the local pH to stay below the threshold for calcium precipitation, resulting in Mg(OH)₂ with a purity exceeding 99%.

In a full-scale electrolyzer test, the system continuously recovered high-purity Mg(OH)₂ at a rate of 5.54 g h⁻¹ while maintaining stable hydrogen evolution. This byproduct can be sold to offset the operating costs of hydrogen production.

Future Outlook

While this strategy successfully addresses cathodic scaling, further system-level engineering probably needs to manage biological fouling and reduce the costs of anti-scaling catalysts for large-scale deployment. Nevertheless, this approach marks a major step toward making direct seawater electrolysis a commercially viable reality.

JOURNAL: ENGINEERING Energy 

DOI: 10.1007/s11708-026-1057-1 

Article Link: https://link.springer.com/article/10.1007/s11708-026-1057-1

Cite this article: Wang H, Kou T. Charge-engineered Pt for sustained hydrogen generation and high-purity Mg(OH)₂ co-production in direct seawater electrolysis. ENGINEERING Energy, 2026, 20(2): 10571. https://doi.org/10.1007/s11708-026-1057-1