Recent Progress on Catalysts for Hydrogen Evolution from Decomposition of Hydrous Hydrazine

Hydrogen with remarkable energy density has attracted much attention as the green, sustainable chemical energy carrier and a substitute for traditional fossil fuels. The discovery of safe and efficient hydrogen storage materials for the transition to a hydrogen energy society is one of the biggest challenges for hydrogen energy applications today. Hydrous hydrazine (N2H4H2O), with its high hydrogen content (w8.0%) and the advantage of CO-free hydrogen production, has significant advantages in hydrogen storage and release and is considered as a promising liquid-phase chemical hydrogen storage material. The development of efficient and highly selective catalysts is the key to release hydrogen from the decomposition of hydrous hydrazine. In the past decade, a lot of catalysts have been developed to improve the kinetic properties for hydrogen generation. In this review, we focus on the recent progress on catalyst design, synthesis and catalytic performance of the catalyst in hydrogen production from the selective decomposition of hydrous hydrazine. Ir, Rh and Ni monometallic catalysts were found to be very active toward the dehydrogenation of hydrazine. Among all the catalysts investigated, supported Pt-Ni, Rh-Ni and Pt-Co catalysts showed the highest activity. The mechanism of hydrazine decomposition was briefly analyzed. The cleavage of the N-H bond of N2H4 will facilitate the formation of H2 and N2, while N-N bond cleavage will result in the formation of NH3 and N2. In addition, we reviewed and discussed the strategies for promoting H2 selectivity and activity of catalysts, such as the addition of strong base and/or alkaline carrier, formation of metal alloys, reduction of metal crystallinity and particle size, as well as the enhancement of the interaction between metal and support. The progress of this research may provide guidance for obtaining more active catalysts toward hydrogen production from nitrogen-based hydrides.