RuCo Nanoalloy Catalysts Obtained From In‐Situ Reconstruction of High‐Entropy Oxides for Green Ammonia Synthesis
Xiuyun Wang, Jiahao Yu, Kailin Su, Yangyu Zhang, Yiheng Zhuan, Yanliang Zhou, Haifeng Qi, Lirong Zheng, Junjie Wang, Lilong Jiang, Hideo HosonoABSTRACT
Optimizing promoters is crucial for designing efficient catalysts for ammonia (NH 3 ) synthesis under mild conditions. However, this endeavor is often hampered by a fundamental trade‐off: weak metal‐promoter interactions (MPI) lead to promoter segregation, while excessively strong ones block active sites, both diminishing the efficiency of promotion. In this work, we report a high‐entropy oxide (HEO) nanoparticle catalyst integrated with active metals (Ru/Co) and promoters (La/Ce/Sm) for efficient NH 3 synthesis via an in situ reconstruction strategy. Our investigation reveals that the HEO undergoes in situ reconstruction to form RuCo nanoalloys anchored on rare‐earth oxide nanoislands, which simultaneously realizes the exposure of active sites and strong metal‐promoter interaction. This entropy reduction process facilitates the formation of surface oxygen vacancy sites with low work function electrons, facilitating electron transfer to the metal alloys to drive N 2 dissociation. Furthermore, alloying Ru with Co metal lowers the d‐band center to promote NH 3 desorption. Consequently, the optimized RuCo‐HEO catalyst delivers a remarkable NH 3 synthesis rate of 58.2 mmol g − 1 h − 1 (2.41% concentration) at 400°C and 1 MPa, approaching the thermodynamic equilibrium value (2.44%). This work provides an in situ reconstruction strategy to engineer active sites exposure and promoter effect for efficient green NH 3 synthesis.