Producing hydrogen from seawater is an appealing idea: this resource accounts for about 97% of all water on the planet. But salt creates problems. Chloride ions (dissolved salt) destroy metal catalysts - substances that speed up a reaction - and interfere with the desired oxygen evolution reaction. Toxic chlorine and byproducts may form instead of oxygen.
Researchers from the University of Sharjah (UAE) and their colleagues described in the journal Chemical Communications a new catalyst made of three components: nickel hydroxide, cerium oxide and phosphate. All are widespread in nature and relatively inexpensive. Unlike platinum or iridium, which are often used in the best catalysts, nickel and phosphate are available, and cerium is moderately abundant.
According to co-author Dr. Tanveer Ul Haq, an associate professor of chemistry at the University of Sharjah, the new catalyst requires less energy, is more selective for the desired reaction and corrodes significantly less than analogues without cerium oxide or phosphate. In a stress test it ran continuously under high load for about 80 hours in simulated seawater without breaking down or losing efficiency. However, the authors acknowledge that this is not yet enough time for a commercial installation.
The material forms small, densely packed pyramid-shaped nanostructures. This provides a larger active surface area than conventional nickel hydroxide, meaning more sites for the reaction. Ul Haq stresses that the study does not create a ready commercial product but takes a serious step toward making "green" hydrogen cheaper. If catalysts can operate reliably on untreated seawater, the cost of expensive purification or desalination would be eliminated. This is especially important for coastal industries, island states and regions that have an ocean but little fresh water.
Hydrogen is considered important for reducing emissions in sectors that are hard to electrify directly - steelmaking, shipping and freight transport. However, most hydrogen today is produced using fossil fuels or requires clean water. The new method, according to the authors, does not depend on fossil fuels and can run on renewable electricity.
The study's limitation is obvious: 80 hours of stable operation is only an early signal that the corrosion protection strategy works under realistic saline conditions, not just in theory. There is still a considerable way to go before industrial adoption.