Low-cost, durable anode to split seawater for efficient renewable energy storage

Summary: Research in Prof. Hongjie Dai's laboratory have developed a robust anode that directly converts alkaline seawater to hydrogen fuel at large current densities for at least 1000 hours without corrosion or performance decay.

Background/Problem: Generating hydrogen from water is a promising approach for storing intermittent renewable energy (e.g., solar or wind power). However, current technologies for electrolysis to split water into hydrogen and oxygen require purified water. Therefore, grid-scale electrolysis would put heavy strain on vital water resources. Electrodes (particularly anodes) that can sustain seawater splitting without corrosion could address the water scarcity issue.

Solution: This highly active, corrosion-resistant anode has a unique bi-layer structure that results in long-term stability. The anode is 100% selective for the oxygen evolution reaction (OER), without Cl₂ evolution. In addition, it is fabricated from low-cost, abundant materials. These features enable direct electrolysis on seawater (without costly desalination) at current densities and temperatures that are used in industrial water electrolysis.

Results and Related Technology: This anode/oxygen evolution catalyst can be paired with a cathode developed by the Dai lab (Stanford Docket S18-041, a low-cost hydrogen evolution electrocatalyst). Using these technologies together, the inventors have achieved a high electrolysis current density of 400 mA/cm² for stable alkaline seawater splitting without decay for over 1000 hours under an applied voltage of only 1.72V without anode corrosion or activity loss.

Sustained, energy efficient seawater splitting continuously over 1000 hours. Durability test for electrolysis in an alkaline seawater electrolyte (black), an alkaline simulated seawater electrolyte with near saturated salt concentration (blue) and industrial electrolysis conditions (red).