Highly Active Ni- and Co-Based Bimetallic Catalysts for Hydrogen Production From Ammonia-Borane

• Main Authors: Shinya Furukawa, Genki Nishimura, Tomoaki Takayama, Takayuki Komatsu
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2019-03-01
• Series: Frontiers in Chemistry
• Subjects: hydrogen production; ammonia borane; hydrolysis; alloy; catalyst
• Online Access: https://www.frontiersin.org/article/10.3389/fchem.2019.00138/full

Ammonia-borane is one of the most promising candidates for hydrogen carriers. A series of Ni- and Co-based bimetallic catalysts supported on SiO2 (Ni–M/SiO2 and Co–M/SiO2; M = Ga, Ge, Sn, Zn) was prepared and tested as catalysts for hydrogen production from ammonia-borane (AB) in water or methanol. Ni–Zn/SiO2 and Co–Ge/SiO2 exhibited catalytic activities much higher than those of monometallic Ni/SiO2 and Co/SiO2, respectively. Ni–Zn/SiO2 showed a high catalytic activity when water was used as a solvent, where the reaction was completed within 6 min at room temperature with a specific reaction rate of 4.3 ml min−1 mmol-cat−1 mM-AB−1. To the best of our knowledge, this is the highest value among those reported using 3d metal-based catalysts. Co–Ge/SiO2 afforded a five-fold higher reaction rate than that of the corresponding monometallic Co/SiO2. XRD, TEM, and HAADF-STEM-EDS analyses revealed that Ni0.75Zn0.25 and Co0.8Ge0.2 solid-solution alloys were formed with high phase purities. An XPS study showed that Co atoms in Co0.8Ge0.2 were electron-enriched due to electron transfer from Ge to Co, which may be the origin of the improved catalytic activity.