Ru Single Atom and Nanoparticle Tandem Catalyst Unlocking High-Efficiency Ammonia Synthesis under Mild Conditions
Yanliang Zhou, Bo Yang, Lu Wang, Kailin Su, Ben Liu, Hongpeng Fang, Kexin Yue, Xiuyun Wang, Haifeng Qi, Lirong Zheng, Wei Li, Lilong Jiang
Abstract
The development of highly efficient catalysts that enable Haber–Bosch ammonia (NH 3 ) synthesis under mild conditions remains critically challenging since the competitive activation of coadsorbates, particularly excessive N 2 or H 2 binding at active sites, is a trade-off and detrimental to NH 3 synthesis. Herein, we design a novel Ru tandem catalyst that combines Ru single atom (Ru 1 ) with nanoparticle sites (Ru NP ) on CeO 2 nanoislands, leveraging cascade hydrogen catalysis between functionally distinct Ru sites to realize highly efficient NH 3 synthesis under mild conditions. Our studies reveal that Ru NP sites suffer from hydrogen poisoning, whereas Ru 1 sites exclusively adsorb N 2 . The hydrogen spillover from Ru NP to Ru 1 sites reduces hydrogen coverage on Ru NP sites to effectively decrease the N 2 dissociation barrier and also greatly facilitates N 2 hydrogenation at Ru 1 sites for NH 3 synthesis, thus overcoming the trade-off in the dynamic N 2 /H 2 activation equilibrium. As a result, the Ru single atom and nanoparticle tandem catalyst achieves a remarkable NH 3 synthesis rate of 59.0 mmol g cat –1 h –1 with 600 h long-term operational stability at 400 °C and 1 MPa, possessing an exceptionally high specific rate among reported Ru-based catalysts. This catalyst structure design paves a new path for NH 3 synthesis under mild conditions.