Hydrous hydrazine, such as hydrazine monohydrate (N2H4 center dot H2O), is a promising hydrogen carrier material due to its high content of hydrogen (8.0 wt%). The decomposition of hydrous hydrazine to H-2 with a high selectivity and a high activity under mild conditions is the key to its potential usage as a hydrogen carrier material. Platinum-modified Ni/Al2O3 catalysts (NiPtx/Al2O3) were prepared starting from Ni-Al hydrotalcite and tested in the decomposition of hydrous hydrazine. Compared with Ni/Al2O3, the TOF was enhanced sevenfold over NiPt0.057/Al2O3; meanwhile, the selectivity to H-2 was increased to 98%. Characterization results by means of HAADF-STEM, XRD, and EXAFS revealed the presence of surface Pt-Ni alloy in this Pt-promoted catalyst. The formation of Pt-Ni alloy could significantly weaken the interaction between adspecies produced (including H-2 and NHx) and surface Ni atoms, which is confirmed by microcalorimetry and TPD results. The weakening effect could account for the greatly enhanced reaction rate, as well as H-2 selectivity on NiPtx/Al2O3 catalysts. (c) 2012 Elsevier Inc. All rights reserved.