Carbon clusters modified Ru-based catalysts for efficient ammonia synthesis under mild conditions

The main difficulty in ammonia (NH3) synthesis under mild conditions is that it is difficult to dissociate and activate N2 molecules (the dissociation energy of N≡N is 945 kJ mol−1), so it is crucial to use appropriate promoters to facilitate the activation of N2. However, traditional elemental promoters can promote the dissociation and activation of N2 while forming strong binding with NH3 on the catalyst surface, thereby inhibiting the desorption of NH3. In this study, the molecular promoter C60 was loaded onto Ru/Pr2O3 to explore its role and reaction mechanism in ammonia synthesis. The research shows that there is a strong interaction between C60 and the Ru metal, exhibiting a significant electron buffer attribute. Specifically, C60 provides electrons to Ru, causing the d-band center to shift towards the Fermi level, promoting the adsorption and activation of N2. While exerting the electron buffering attribute, it also promotes the desorption of NH3. Furthermore, the addition of C60 promotes the activation and migration of H species, which helps avoid competitive adsorption of N2 and H2 on metallic Ru sites and alleviates hydrogen poisoning. Therefore, the Ru/5C60-Pr2O3 catalyst modified with an appropriate amount of C60 promoter exhibits excellent performance in ammonia synthesis. This work investigated the role of the molecular promoter C60 in Ru-based ammonia synthesis catalysts, providing new ideas for the development of efficient ammonia synthesis catalysts.