CeOx-modified RhNi nanoparticles grown on rGO as highly efficient catalysts for complete hydrogen generation from hydrazine borane and hydrazine

Abstract

CeO_x-modified RhNi nanoparticles (NPs) grown on reduced graphene oxide (rGO) (RhNi@CeO_x/rGO) have been facilely prepared and successfully used as highly efficient catalysts for the rapid and complete hydrogen generation from aqueous solution of hydrazine borane (N₂H₄BH₃) and hydrazine (N₂H₄), respectively. It was found that the CeO_x-doped RhNi NPs with a size of around 3.5 nm were highly dispersed on rGO nanosheets. Among all the catalysts investigated, the optimized catalyst Rh_0.8Ni_0.2@CeO_x/rGO with a CeO_x content of 13.9 mol% exhibited the highest catalytic performance. The total turnover frequency (TOF) of Rh_0.8Ni_0.2@CeO_x/rGO for hydrogen generation from N₂H₄BH₃ reached 666.7 h⁻¹ (mol_H2 mol_(Rh+Ni)⁻¹ h⁻¹) at 323 K, which was among the highest of all the catalysts reported to date for this reaction, 10-fold higher than that of the benchmark catalyst Rh_0.8Ni_0.2, and 3-fold higher than that of Rh_0.8Ni_0.2 with a CeO_x dopant (Rh_0.8Ni_0.2@CeO_x) and a rGO support (Rh_0.8Ni_0.2/rGO). Even at room temperature, Rh_0.8Ni_0.2@CeO_x/rGO can achieve a complete hydrogen generation from N₂H₄BH₃ and N₂H₄ with a TOF value of 111.2 and 36.4 h⁻¹. This excellent catalytic performance might be attributed to the synergistic structural and electronic effects of the RhNi NPs, CeO_x dopant, and rGO support. Moreover, this general method can be easily extended to facile synthesis of other metal/rGO systems with the doping of rare-earth oxides for more applications.