Monometallic Rh nanocatalysts supported on CeO2 microcuboids for highly efficient dehydrogenation of hydrous hydrazine

Abstract

The development of efficient catalysts for hydrogen production from hydrous hydrazine (N₂H₄·H₂O) poses a significant challenge in the field of renewable energy. In this study, a series of monometallic rhodium nanocatalysts supported on shape-controlled CeO₂ were successfully prepared via a one-step wet chemical reduction method. Among the CeO₂ supports with different morphologies, the Rh catalyst supported on CeO₂ microcuboids (Rh/CeO₂-MC) exhibited the most outstanding catalytic activity for the N₂H₄·H₂O dehydrogenation reaction. Under alkaline conditions at 323 K, the Rh/CeO₂-MC catalyst with 5 wt% Rh loading showed the highest activity, achieving 100% hydrogen selectivity—the first reported for a supported monometallic Rh catalyst—along with a turnover frequency (TOF) of 320 h⁻¹, which significantly surpasses that of most previously reported monometallic catalysts. The enhanced catalytic performance can be attributed to two main factors. First, the alkaline reaction environment plays a key role in promoting the dehydrogenation process. Second, the CeO₂-MC support possesses a series of structural advantages, including a high specific surface area (87.29 m² g⁻¹), abundant oxygen vacancies, and strong metal–support interactions. These features effectively regulate the size and dispersion of Rh nanoparticles (NPs) and optimize interfacial charge transfer, thereby significantly improving the catalyst's activity and selectivity. Based on the above support-engineering strategy, this study achieved efficient and complete dehydrogenation of both hydrous hydrazine and hydrazine borane (N₂H₄BH₃) in a monometallic system, providing a new approach for the design of high-performance dehydrogenation catalysts.