Yale researchers have developed a promising new method to electrochemically convert nitrate—a common and harmful water pollutant—into ammonia. This innovation offers two major benefits: purifying contaminated water and generating a valuable product that can be used for fertilizers and carbon-free fuels.

Nitrate, while essential for plant growth, is a prevalent contaminant in wastewater and can significantly harm water quality when overly abundant. Converting nitrate into ammonia is not a new idea, but doing so efficiently and affordably has remained a major challenge. Scientists have long struggled to achieve both high selectivity—minimizing unwanted byproducts—and high activity, which refers to the speed of conversion.

Traditional approaches have focused on expensive, complex materials to boost these conversion rates. Advanced electrocatalysts can enhance performance, but they come with high costs, especially when applied on a large scale for wastewater treatment. According to Yale Professor Lea Winter, the use of costly and intricate nanostructures significantly raises the economic barrier.

To address this, Professor Winter and her team introduced a two-part solution that marks a major advancement.

The first component is an ionophore—essentially a molecular magnet—that captures nitrite, an intermediate byproduct that typically escapes before it can be fully converted. By holding nitrite in place, the system ensures it is completely transformed into ammonia, greatly increasing the overall yield. This mechanism dramatically boosts the system’s ammonia selectivity.

The second innovation is an electrified membrane that acts as a high-speed electrochemical conversion platform. The membrane operates so rapidly that it typically produces large amounts of nitrite. However, when paired with the ionophore, the system maintains both exceptional speed and selectivity.

Together, these innovations enable the conversion of nitrate into ammonia in just six seconds—a process that normally takes hours—with a remarkable 92 percent conversion efficiency. The team also demonstrated the system’s durability by successfully treating real samples of lake water and wastewater, where it remained stable for hours, proving its real-world applicability.

This breakthrough represents a significant step forward in sustainable chemistry, offering a dual solution to two global challenges: water pollution and the demand for eco-friendly ammonia production.

By Impact Lab