La(OH)3 nanosheet-supported CoPt nanoparticles: a highly efficient and magnetically recyclable catalyst for hydrogen production from hydrazine in aqueous solution

Abstract

Hydrous hydrazine (N₂H₄·H₂O) is considered to be a promising chemical hydrogen storage carrier due to its high hydrogen content (8.0 wt%), production of only N₂ in addition to H₂, and facile recharging as a stable liquid. In this work, for the first time, CoPt NPs supported on La(OH)₃ are used as a highly effective catalyst for selective decomposition of N₂H₄. Surprisingly, the La(OH)₃ nanosheet-supported CoPt NPs exhibit superior catalytic performance, releasing 3 equiv. (H₂ + N₂) with turnover frequency (TOF) values of up to 734.2 h⁻¹ at 303 K and 2400 h⁻¹ at 323 K; these are higher than those of most reported catalysts for the dehydrogenation of N₂H₄. Especially, CoPt/La(OH)₃ can be easily separated from the reaction solution using a magnet due to its super-paramagnetic nature, and it can maintain its high activity and 100% selectivity even after five cycles. The high performance of CoPt/La(OH)₃ can be attributed to the electronic interaction between Co and Pt, strong basic sites on the surface of La(OH)₃ and a synergistic cooperative effect between the ultrafine CoPt NPs and the La(OH)₃ support. The development of a high performance Co-based catalyst may promote the effective application of hydrous hydrazine as a promising hydrogen storage material.