Hydrogen production via selective dehydrogenation of hydrazine borane and hydrous hydrazine over MoOx-promoted Rh catalyst

Hydrazine borane (N 2 H 4 BH 3 , 15.4 wt%) and hydrous hydrazine (N 2 H 4 ·H 2 O, 8 wt%) are promising chemical hydrogen storage materials that have attracted much attention in recent years due to their high gravimetric hydrogen capacities. The selective and rapid catalytic dehydrogenation of N 2 H 4 BH 3 and N 2 H 4 ·H 2 O is the key to the potential use of the abovementioned materials in hydrogen applications. In this study, a series of Rh-MoO x nanoparticles (NPs) with various metal compositions have been successfully prepared via a simple one-step chemical reduction approach in the absence of a surfactant/support at room temperature . The obtained surfactant/support-free Rh-MoO x NPs exhibit good dispersibility and small particle size. Among all of the as-prepared Rh-MoO x NPs, the optimized Rh-MoO x catalysts with a molar ratio of 1:1 show the highest catalytic properties with 100% H 2 selectivity for hydrogen evolution from aqueous N 2 H 4 BH 3 and N 2 H 4 ·H 2 O solutions at 323 K under alkaline conditions. The turnover frequency (TOF) values of Rh 0.5 (MoO x ) 0.5 NPs are 2000 and 750 h −1 for hydrogen evolution from N 2 H 4 BH 3 and N 2 H 4 ·H 2 O , respectively, which are among the highest values ever reported for Rh-based catalysts. The superior catalytic performances could be attributed to the small particles size, low crystallinity , modified electronic structure, and strong basic sites of Rh NPs induced by the MoO x dopant . The highly rapid and selective Rh-MoO x catalyst may further encourage the deployment and application of N 2 H 4 BH 3 and N 2 H 4 ·H 2 O as safe and convenient sources of hydrogen for fuel cells.