Galvanic replacement synthesis of NiPt/graphene as highly efficient catalysts for hydrogen release from hydrazine and hydrazine borane

NiPt nanoparticles (NPs) supported on graphene nanosheets were successfully synthesized via a galvanic replacement approach at room temperature with precursor Ni NPs as a sacrificial template. The as-synthesized NiPt/graphene catalysts were characterized by inductively coupled plasma, X-ray diffraction, transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, X-photoelectron spectroscopy, and BET surface area measurement, and used as catalysts for H-2 production from hydrazine and hydrazine borane. The characterization data showed that NiPt NPs with a small size of around 3.5 nm were dispersed on the graphene nanosheets. The as-synthesized NiPt/graphene exhibited high activity and 100% hydrogen selectivity toward the conversion of hydrazine or hydrazine borane to hydrogen. The turnover frequency (TOF) values of Ni0.58Pt0.42/graphene reached 434 h(-1) at 30 degrees C and 846 h(-1) at 50 degrees C for the decomposition of hydrazine, respectively, which are higher than those of most of the reported catalysts. In particular, a high TOF value of 2303 h(-1) at 50 degrees C was obtained for dehydrogenation of hydrazine borane, which is among the highest for all the catalysts reported to date. The as-synthesized Ni0.58Pt0.42/graphene exhibited satisfactory durability for hydrogen evolution from hydrazine and hydrazine borane. This excellent catalytic performance could be attributed to the strong interaction of NiPt NPs and graphene, the small size and high dispersion of NiPt NPs, and NaOH promotion. The development of high catalytic activity catalysts is a promising step towards the application of hydrazine and hydrazine borane as hydrogen storage material. (C) 2016 Elsevier B.V. All rights reserved.