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Abstract: Au–Cu bimetallic nanoparticles supported on SBA-15 have been reported to be much more active in CO oxidation than the corresponding monometallic counterparts in our previous work. In this work, in situ techniques including XRD, EPR, XANES, and FT-IR were employed to reveal the structural changes of the Au–Cu bimetallic particles during different pretreatment and reaction conditions, and to clarify the essence of the synergistic effect between gold and copper. The results showed that gold remained as Au0 in any treatment conditions, while copper was very sensitive to the treatment temperature and atmosphere. The freshly reduced catalyst was a mixture of Au3Cu1 intermetallic phase and Cu2O amorphous phase. In CO oxidation, the Au3Cu1 intermetallic phase was segregated into a gold core decorated with tiny CuO x patches, and CO adsorbed on Au0 reacted with active oxygen provided by the neighboring CuO x , thus enhancing greatly the activity for CO oxidation. [Copyright &y& Elsevier]

Abstract: Hydrous hydrazine, such as hydrazine monohydrate (N2H4·H2O), is a promising hydrogen carrier material due to its high content of hydrogen (8.0wt%). The decomposition of hydrous hydrazine to H2 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 (NiPt x /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 H2 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 H2 and NH x ) 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 H2 selectivity on NiPt x /Al2O3 catalysts. [Copyright &y& Elsevier]