Retracted Article: Synthesis of octahedral, truncated octahedral, and cubic Rh2Ni nanocrystals and their structure–activity relationship for the decomposition of hydrazine in aqueous solution to hydrogen

Abstract

We developed a co-reduction method to synthesize octahedral, truncated octahedral, and cubic Rh₂Ni nanocrystals. The shape/size distribution, structural characteristics, and composition of the Rh₂Ni nanocrystals are investigated, and their possible formation mechanism at high temperatures in margaric acid/1-aminoheptadecane solution in the presence of tetraethylgermanium and borane trimethylamine complexes is proposed. A preliminary probing of the structure–activity dependence of the surface “clean” Rh₂Ni nanocrystals supported on carbon towards hydrazine (N₂H₄) in aqueous solution dehydrogenation revealed that the higher the percentage of {111} facets, the higher is the activity and H₂ selectivity of the nanocrystals. This result was attributed to the {111} facets not only introducing more basic sites, but also weakening the interaction between the produced adspecies (including H₂ and NH_x) and surface metal atoms in comparison with those of {100} facets. Furthermore, the as-prepared Rh₂Ni nanooctahedra exhibited 100% H₂ selectivity and high activity at room temperature for H₂ generation via N₂H₄ decomposition. The activation energy of the Rh₂Ni nanooctahedra was 41.6 ± 1.2 kJ mol⁻¹. The Rh₂Ni nanooctahedra were stable catalysts for the hydrolytic dehydrogenation of N₂H₄, providing 27 723 total turnovers in 30 h. Our work provides a new perspective concerning the possibility of constructing hydrogen-producing systems based on N₂H₄ and surface “clean” Rh₂Ni nanocrystal catalysts with defined shapes supported on carbon that possess a competitive performance in comparison with NaBH₄ and NH₃BH₃ hydrogen-producing systems for fuel cell applications.