Durable, High-Performance Water Electrolyzer Operating on Impure Water Feedstock

Hydrogen is an excellent alternative to fossil fuels because it is storable, transportable, and burns cleanly, producing power without polluting the environment. Electrolyzers, which can generate hydrogen from water and electricity, are an ideal way to produce a clean, renewable fuel. Impure water electrolyzers can enable direct coupling of electrolyzers with offshore wind and electrolyzer operation in water stressed areas. Using impure water has a significant effect on the durability and efficiency of traditional electrolyzers through fouling of the catalysts and membranes. We are proposing to develop a low temperature water electrolyzer that can operate with tap water or even brinier water sources. We will develop catalysts and electrodes that will have increased tolerance for salts, particularly chlorides, during electrolyzer operation. This impure water electrolyzer will be ideally suited for integration with renewable energy sources like solar and offshore wind farms, or in water-starved areas. We successfully demonstrated stable operation of our electrolyzer in up to 1000 ppm NaCl salt water without loss of performance compared with tap and pure water operation. We demonstrated over 200h operation in 100 ppm NaCl without any noticeable increase in operating voltage at a constant current densitry. We also showed improved activity and stability for oxygen evolution reaction catalysts synthesized during this project compared with baseline catalysts. In this project, we will build on our previous success demonstrating high activity anion exchange membrane electrolyzers operating with impure water feedstocks. We will further improve the precious group metal-free catalysts and electrodes with high tolerance for salts previously demonstrated by combining their stability and activity. These state-of-the-art catalysts and electrodes will be integrated with our established electrolyzer platform to improve the activity and durability of electrolyzers operating with impure water. Integration of electrolyzers with renewables, enabled by impure water electrolysis, would lead to significant reductions in greenhouse gas emissions for production of hydrogen. By using an alkaline-based device the need for expensive and rare catalysts is reduced or eliminated, reducing the cost of the device. Development of impure water electrolyzers would enable progress in other membrane-based technologies that currently require ultrapure water. The use of seawater or briny water as an electrolyzer feedstock could open the door to utilizing seawater for a variety of other applications in drinking water-starved areas by eliminating costly purification steps.