Accelerated Nitrate to Ammonia Conversion with Sustainable Catalyst

Atomically ordered ruthenium-gallium sites steer nitrate away from wasteful reactions, boosting ammonia yields while powering a zinc-nitrate battery for hundreds of hours.

Study: Atomically Ordered RuGa Intermetallic Electrocatalyst Enables High-Efficiency Nitrate-to-Ammonia Conversion. Image Credit:  ThamKC/Shutterstock.com

A research team at Tohoku University has engineered an electrocatalyst capable of transforming nitrate, a common pollutant in groundwater and agricultural runoff, into ammonia under considerably milder conditions. The study was published in the journal Advanced Functional Materials.

Ammonia is fundamental to agriculture, supports various industries, and is increasingly recognized as a vital component in future clean-energy systems. However, it requires large volumes of energy and high levels of heat and pressure. 

Our new catalyst has two main benefits: first, it reduces the emissions linked to fertilizer and chemical manufacturing, and second, it enables us to essentially recycle nitrate, which would otherwise pollute our water.

Hao Li, Distinguished Professor, Advanced Institute for Materials Research (WPI-AIMR), Tohoku University

The catalyst is composed of an atomically ordered alloy of ruthenium (Ru) and gallium (Ga), forming a ruthenium-gallium intermetallic compound supported on carbon (RuGa IMC/C).

Its unique structure precisely positions individual ruthenium atoms, surrounded by gallium. Gallium does not directly react but critically shapes the environment in which each ruthenium site functions, thereby guiding nitrate (NO₃^-) toward the specific reaction steps that produce ammonia (NH₃).

The catalyst efficiently converts nitrate even at low concentrations, operating at a very gentle voltage.

It maintains selectivity across a broad concentration range and demonstrated consistent performance in tests, proving that careful atomic design can encourage nitrate conversion under realistic environmental conditions.

Computer simulations conducted by the researchers elucidated the catalyst's high efficacy. The introduction of gallium modifies the electronic characteristics of ruthenium, influencing how nitrogen-containing molecules attach and transform on the surface. This adjustment also suppresses hydrogen formation, a competing reaction that frequently limits ammonia yields.

The catalyst was also tested within a zinc-nitrate battery. The zinc-nitrate system produced consistent power and operated for hundreds of hours, indicating the material's applicability in both chemical production and energy-related systems.

We hope to convert a widespread pollutant into a valuable product and offer guidance for designing future catalysts that take advantage of controlled atomic ordering.

Hao Li, Distinguished Professor, Advanced Institute for Materials Research (WPI-AIMR), Tohoku University

The researchers now plan to expand their theoretical modeling efforts, integrating machine-learning tools to map reaction pathways more effectively. The study aims to accelerate the design of next-generation electrocatalysts for sustainable chemical production.

Journal Reference:

Wu, Z., et al. (2025) Atomically Ordered RuGa Intermetallic Electrocatalyst Enables High-Efficiency Nitrate-to-Ammonia Conversion. Advanced Functional Materials.  DOI: 10.1002/adfm.202524120. https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202524120