Dual active sites for ammonia synthesis at ambient pressure

Abstract

Numerous theoretical calculations indicate the synergistic role of bimetals to efficiently activate nitrogen molecules and facilitate ammonia formation through dissociative routes. Here, we experimentally demonstrated the use of dual active sites comprised of Fe with Ru, Co, and Ni. The findings reveal that Ru/Fe and Co/Fe catalysts are stable and effective to form ammonia at ambient pressure and in the temperature range (400–550 °C) with an activation energy of 45.73 kJ∙mol−1 and 46.38 kJ∙mol−1, respectively. In addition to extensive characterizations, an in-depth kinetic study unveils that the inclusion of Ru or Co to the Fe can shift the rate-determining steps to NHx formation. The co-catalysts are negatively charged because of electron-donating Fe sites, which helps to favor N2 dissociation on the bimetallic catalysts.