Nickel-palladium nanoparticle catalyzed hydrogen generation from hydrous hydrazine for chemical hydrogen storage

In this study, we report Ni-Pd bimetallic nanoparticle catalysts (nanocatalyst) (Ni1-xPdx) synthesized by alloying Ni and Pd with varying Pd contents, which exhibit appreciably high H2 selectivity (>80% at x = 0.40) from the decomposition of hydrous hydrazine at mild reaction condition with Ni0.60Pd0.40 nanocatalyst, whereas the corresponding monometallic counterparts are either inactive (Pd nanoparticles) or poorly active (Ni nanoparticles exhibit 33% H2 selectivity). In addition to powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) analysis and electron microscopy (TEM/SEM), the structural and electronic characteristics of Ni-Pd nanocatalysts were investigated and established using extended X-ray absorption fine structure (EXAFS) analysis. Unlike the high activity of Ni-Pd nanocatalysts, Pd-M (M = Fe, Co and Cu) bimetallic nanocatalysts exhibit poor catalytic activity. These results imply that alloy composition of Ni-Pd nanocatalysts is critical, where the co-existence of both the metals on the catalyst active surface and the formation of inter-metallic Ni-Pd bond results in high catalytic performance for the decomposition of hydrous hydrazine to hydrogen.

Graphical abstractBimetallic nickel-palladium nanocatalysts Ni1-xPdx, synthesized by alloying Ni and Pd with varying Pd content, exhibit appreciably high catalytic performance for hydrogen generation from hydrazine (>80% at x = 0.40) due to the presence of active Ni-Pd alloy phase, which is well characterized by XPS, EXAFS and electron microscopy.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Bimetallic alloy nanoparticle catalysts (nanocatalyst) for hydrogen generation from hydrous hydrazine decomposition. ► At moderately elevated reaction temperature of 323 K, Ni1-xPdx bimetallic nanocatalysts exhibits high catalytic performance. ► Alloying Ni with Pd (x = 0.40) exhibits >80% selectivity for hydrogen from hydrous hydrazine decomposition at 323 K. ► Pd nanoparticles exhibits no activity for hydrous hydrazine decomposition at 323 K.