Layered Nanochemistry Group

Sodium borohydride (NaBH₄, SBH) is a high-capacity hydrogen-storage particulate material that releases hydrogen via catalytic hydrolysis at lower temperatures. Although the United States Department of Energy (DOE) proposed a no-go recommendation for SBH hydrolysis for onboard system applications mainly due to the high cost of SBH and its regeneration, SBH is still considered to be an attractive candidate because a Japanese company (Nippon Light Metal Company, Ltd.) developed a low-cost production and re-generation method in 2019. On the other hand, the development of efficient and cost-effective catalysts for the dehydrogenation of SBH remains challenging.

We report that a mixed-valent [Fe^II−Fe^III] iron hydroxide, which we term green rust (GR, a family of layered double hydroxide), treated with a CuCl₂ solution, shows a good catalytic activity toward SBH hydrolysis. The GR-based catalyst exhibits turnover frequency of up to 5000 min^–1 for the hydrolysis of SBH that is comparable to or one or two orders of magnitude higher than existing catalysts based on novel and precious metals tested under similar conditions.