Nitrogen-based fertilizers are essential for modern agriculture, and compounds like ammonia and urea are also widely used in industry. However, their conventional production and use pose major environmental challenges. The industrial synthesis of ammonia through the Haber-Bosch process consumes vast amounts of energy, while excessive fertilizer runoff contaminates soil and water. Moreover, nitrous oxide, a byproduct of nitrogen compound production, is a potent greenhouse gas with nearly 300 times the global warming potential of carbon dioxide. "Pulsed electrolysis could offer a sustainable alternative," says Dr. Dandan Gao, a chemist at Johannes Gutenberg University Mainz (JGU). "This emerging method uses excess nitrogen from air and water as the starting material, enabling the energy-efficient production of valuable compounds such as ammonia and urea." In a recently published Minireview in Angewandte Chemie, Gao, colleagues from JGU, and collaborators from the Harbin Institute of Technology in Shenzhen, China, summarize the latest progress in this promising field and outline key directions for future research. "By providing a clear overview of what has been achieved so far and what remains to be explored, we aim to accelerate advances toward sustainable nitrogen conversion," Gao explains. "Ultimately, we want to help turn waste nitrogen in the environment into useful products."

Traditionally, ammonia is produced through the Haber-Bosch process, which requires high temperatures (400 to 500 degrees Celsius) and pressures, making it highly energy-intensive. In contrast, pulsed electrolysis enables ammonia and even urea formation at room temperature using electricity, ideally sourced from solar or wind power. In this process, two electrodes are immersed in nitrate- or nitrite-containing water. When an electrical voltage is applied, these nitrogen compounds are reduced to ammonia. Unlike conventional electrolysis, pulsed electrolysis varies the voltage and current, which not only enhances reaction efficiency but can also align naturally with intermittent renewable energy sources.

Comparison of results from all available studies

"Because a comprehensive overview of this topic was still missing, we analyzed all available studies on pulsed electrolysis and compared their findings," says Gao. "Our goal is to highlight the potential of this environmentally relevant technology and provide a roadmap for future work." In the long run, Gao envisions that pulsed electrolysis could help redefine the nitrogen cycle, making fertilizer production cleaner, more efficient, and better aligned with a renewable energy future.