Uniform dispersion of ultrafine ruthenium nanoparticles on nano-cube ceria as efficient catalysts for hydrogen production from ammonia-borane hydrolysis

• Published in: Sustainable energy & fuels 2023-01, Vol.7 (3), p.821-831
• Main Authors: Peng, Zhiwei, Wang, Yuhuan, Yin, Chengwang, Qiu, Shujun, Xia, Yongpeng, Zou, Yongjin, Xu, Fen, Sun, Lixian, Chu, Hailiang
• Format: Article
• Language: English
• Subjects: Ammonia; Boranes; Catalysts; Catalytic activity; Cerium oxides; Dehydrogenation; Hydrogen; Hydrogen production; Hydrogen storage materials; Hydrolysis; Metal particles; Nanoparticles; Ruthenium; Ultrafines
• ISSN: 2398-4902; 2398-4902
• DOI: 10.1039/d2se01542k

Ammonia-borane (NH 3 BH 3 , AB) is an valuable chemical hydrogen storage material due to its large hydrogen content of 19.6 wt%, superior stability, and environmental benignity. Highly active catalysts play an indispensable role in hydrogen production from AB hydrolysis. However, it remains a big challenge to achieve that kind of catalyst, i.e. , small uniform size and homogeneous dispersion of metal particles on an oxide support. In this work, nano-cube ceria was successfully synthesized through a hydrothermal method. Two different catalysts, Ru/CeO 2 -NaBH 4 and Ru/CeO 2 -H 2 /Ar, were prepared by loading ultrafine ruthenium nanoparticles on nano-cube ceria through the reduction of Ru 3+ ions by NaBH 4 in solution and H 2 /Ar mixed gas, respectively. The characterization results show that the ruthenium nanoparticles in a very narrow size range of 0.90-2.26 nm are uniformly dispersed on the surface of nano-cube ceria with the existence of Ce 3+ and rich oxygen vacancies, thus providing a strong metal-support interaction. Therefore, even with a small amount of ruthenium (1.6 wt%), Ru/CeO 2 -H 2 /Ar exhibits a relatively low activation energy ( E a ) of 42.98 kJ mol −1 and high catalytic activity with a turnover frequency (TOF) of 176.9 mol H 2 mol Ru −1 min −1 for the catalytic hydrolytic dehydrogenation of AB. Additionally, about 65.8% of catalytic activity is retained after five consecutive tests. This work provides a general strategy to achieve high-performance supported catalysts with ultrafine metal nanoparticles in a uniform distribution. Ultrafine Ru nanoparticles supported on nano-cube ceria with Ce 3+ and oxygen vacancies can provide a strong metal-support interaction, thereby exhibiting superior catalytic performance toward AB hydrolysis.