Oct 2023
Abstract
Ammonia synthesis is one of the most important catalytic processes in the chemical industry. While Fe and Ru are efficient for N≡N bond cleavage, low cost and earth abundant elements such as Ni and Co exhibit much poorer activity due to their weak nitrogen adsorption energy. Here, we report that Ni, Co-loaded rare-earth nitride works as stable and highly efficient catalyst for ammonia synthesis along with a new mechanism. A high density of nitride vacancies is formed with low formation energy, which enables N2 activation at the vacancy sites. Consequently, the reaction rate and turnover frequency (TOF) of the nitride catalysts are quite high at 400 °C and under ambient pressure, and even comparable to those of Ru-based catalysts. Kinetic analysis and isotope experiments combined with density functional theory (DFT) calculations indicate that the nitrogen vacancies generated play a dominant role in the reaction mechanism, and contribute to both the adsorption and activation of N2 molecules. These results indicate the potential role of vacancy sites in the reaction cycles, and provide a new catalyst design concept for earth-abundant catalysts in ammonia synthesis.
Bio
Dr. Tian-Nan Ye received his PhD degree from Shanghai Jiao Tong University. After that, he joined the Materials Research Center for Element Strategy and worked as a specially appointed assistant professor. During this period, he also received JSPS postdoctoral fellowship and became a JSPS Fellow Researcher at Tokyo Institute of Technology. He is currently an associate professor at the Frontiers Science Center for Transformative Molecules of Shanghai Jiao Tong University. He has received several awards including ACS Catalysis Award for Early Career Researcher (2018), Excellent Overseas Young Investigator Award from National Natural Science Foundation of China (2021). His research interests involve the development of inorganic functional materials and their applications in the catalysis and energy fields.