Developing an eco-friendly ammonia catalyst

A DGIST research team led by Professor Sangaraju Shanmugam, Department of Energy Engineering, developed a catalyst that converts nitric oxide (NO) to ammonia (NH₃). This electrochemical technology offers high Faradaic efficiency and low overpotential and produces NH₃ in an eco-friendly manner.

NH₃ is an important chemical raw material in the fertilizer, textile, and pharmaceutical industries, and it is considered a carbon-free hydrogen carrier with a high energy density. Typically, NH₃ is produced using the Haber–Bosch process; however, this process is responsible for approximately 1–2% of global CO₂ emissions.

The electrochemical conversion of NO to NH₃, an alternative to the Haber–Bosch process, has received considerable attention. This eco-friendly method consumes the air pollutant NO gas to produce NH₃. Therefore, this promising approach can replace conventional methods without affecting the environment or emitting CO₂.

However, owing to the corrosive nature of NO gas, the morphology of the metal-nanoparticle electrocatalyst degrades during electrosynthesis. Therefore, it is necessary to obtain a catalyst material with high stability that facilitates long-term electrochemical NH₃ synthesis.

Professor Shanmugam's research team developed a core-shell nickel nanoparticle coated with nitrogen-doped carbon nanostructured electrocatalysts via a simple co-precipitation method for stable NH₃ production. This catalyst is stable and efficient and offers a high Faradaic efficiency of 72.3% at a low overpotential (550 mV) in a 100% NO-saturated electrolyte.

Additionally, a solar-to-NH₃ efficiency of 1.7% and Faradaic efficiency of more than 50% were achieved using a solar-energy-assisted full-cell PV-NORR electrolyzer.

Professor Shanmugam says that "this research has developed an energy-efficient and eco-friendly technology to synthesize NH₃ with zero carbon footprint, and we hope to commercialize this technology to contribute to environmental conservation and sustainability."

The findings of this research were published in Advanced Science.