Spin-mediated promotion of Co catalysts for ammonia synthesis

• 成果类型: Article
• 署名作者: Zhang, Ke; Cao, Ang; Wandall, Lau Halkier; Vernieres, Jerome; Kibsgaard, Jakob; Norskov, Jens K.; Chorkendorff, Ib
• 署名单位: Technical University of Denmark
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-10210
• DOI: 10.1126/science.adn0558
• 发表日期: 2024-03-22
• 页码: 1357-1363
• 关键词: activation; nitrogen; cobalt; oxygen; potassium; electride; lanthanum; oxidation; DYNAMICS; SURFACES

摘要

Over the past two decades, there has been growing interest in developing catalysts to enable Haber-Bosch ammonia synthesis under milder conditions than currently pertain. Rational catalyst design requires theoretical guidance and clear mechanistic understanding. Recently, a spin-mediated promotion mechanism was proposed to activate traditionally unreactive magnetic materials such as cobalt (Co) for ammonia synthesis by introducing hetero metal atoms bound to the active site of the catalyst surface. We combined theory and experiment to validate this promotion mechanism on a lanthanum (La)/Co system. By conducting model catalyst studies on Co single crystals and mass-selected Co nanoparticles at ambient pressure, we identified the active site for ammonia synthesis as the B-5 site of Co steps with La adsorption. The turnover frequency of 0.47 +/- 0.03 per second achieved on the La/Co system at 350degree celsius and 1 bar surpasses those of other model catalysts tested under identical conditions.