Improvement on hydrogen generation properties of Zr(BH₄)₄·8NH₃

Abstract

Hydrolysis of Zr(BH4)4·8NH3 in deionized water can generate high purity hydrogen at room temperature. However, the sluggish hydrolysis kinetics of Zr(BH4)4·8NH3 hinders its practical use. To improve its hydrogen generation properties, the effects of magnetic stirring, changing hydrolysis solution and tuning the ammonia coordination number on the hydrolysis properties of Zr(BH4)4·8NH3 were investigated. Results show that both changing hydrolysis solution and tuning the ammonia coordination number can enhance the hydrolysis kinetics. The hydrolysis kinetics properties of Zr(BH4)4·8NH3 were significantly improved in MgCl2 and CoCl2 solutions. The Zr(BH4)4·xNH3 (x ≤ 8) samples were synthesized by a ball-milling method with different ammonization time (10, 60 and 180 min). Both the hydrolysis kinetics and hydrogen yield of Zr(BH4)4·xNH3 (x ≤ 8) were enhanced as the ammonia coordination number (x) decreased. Thus, tuning ammonia coordination number is an effective way to control the hydrolysis properties of Zr(BH4)4·xNH3 (x ≤ 8).