Seawater-to-Hydrogen Technology by Researchers of China

Seawater-to-Hydrogen Technology by Researchers of China

Here’s an article posted in Spectrum

According to the article,

• Researchers in China have developed a device that can directly split seawater to produce hydrogen fuel, offering a sustainable and practical route to making hydrogen.
• This technology is a significant step towards using renewable electricity to produce hydrogen, which is considered the cleanest route to hydrogen fuel production.

The process described involves using a novel electrolysis system to split seawater into hydrogen and oxygen, offering a sustainable and practical method for hydrogen production.

1. Electrolysis of Seawater: Seawater electrolysis involves passing an electric current through seawater, which contains dissolved ions such as sodium, chloride, magnesium, and calcium. Traditional electrolyzers utilize two catalyst-coated electrodes, typically made of materials like platinum or nickel, to facilitate the electrolysis process. However, impurities present in seawater can cause side reactions and corrosion, reducing efficiency and device lifespan.
2. Challenges with Seawater Electrolysis: Chloride ions in seawater react at the anode to produce chlorine gas, a highly reactive and corrosive substance. This leads to degradation of the catalysts and electrodes, impacting device performance. Additionally, other ions like magnesium and calcium form by-products that can block membranes, further reducing efficiency.
3. Innovative Design: Researchers from Nanjing Tech University and Shenzhen University developed a unique electrolysis system to address these challenges. Their device features two electrodes immersed in a concentrated potassium hydroxide (KOH) electrolyte solution, separated from seawater by porous membranes. The membranes prevent impurities from reaching the electrodes, minimizing side reactions and corrosion.
4. Water Vapor Generation: When electricity is passed through the electrodes, water in the electrolyte solution is split into hydrogen and oxygen. The concentration of the electrolyte increases, creating a pressure difference that causes seawater to evaporate. Water vapor passes through the membranes into the electrolyte, where it condenses back into liquid water, replenishing the supply for electrolysis.
5. Continuous Operation: This design ensures a constant flow of clean water to the electrodes, maintaining efficient electrolysis without the need for additional energy to pump water into the system. The use of a fluorine-rich membrane with low cost and antifouling properties further enhances the system’s practicality and cost-effectiveness.
6. Performance Testing: The researchers constructed a demonstration device with 11 electrolysis cells and tested it using real seawater from Shenzhen Bay. The system operated successfully for over 130 days without failure, producing 386 liters of hydrogen per hour.
7. Future Improvements: The researchers aim to enhance the system’s efficiency by exploring alternative electrolytes and electrode/catalyst materials. They also suggest potential applications beyond hydrogen production, such as recovering valuable resources like lithium from water and cleaning industrial wastewater.

Interestingly, we have some other posts related to this content:

Hydrogen Production from Seawater: New System by Researchers: Innovative system converts seawater into hydrogen fuel, providing a sustainable energy source and enhancing understanding of seawater ion movement. Double-Membrane Electrolysis: A New Method for Producing Hydrogen Directly from Seawater – A new method called double-membrane electrolysis enables the extraction of hydrogen directly from seawater, operating without creating toxic by-products like bleach and chlorine.