Biopolymer-induced microstructure-controlled fabrication of Ni–Al layered double hydroxide films

Novel three-dimensional nanostructured Ni–Al layered double hydroxide (NiAl-LDH) films on sulfonated silicon substrates have been successfully fabricated using a facile biopolymer-induced approach. The structure and morphology of materials were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), chemical analysis, X-ray photoelectron spectrum (XPS) and high-resolution transmission electron microscopy (HRTEM). The results revealed that unique self-organized NiAl-LDH architectures composed of numerous individual curved nanosheets on substrates could be tuned readily by varying the concentration of initial metal ions with the assistance of sodium alginate. A possible formation mechanism for NiAl-LDH film is proposed, on the basis of the interactions between sodium alginate molecules and NiAl-LDH crystals and between NiAl-LDH crystals and sulfonated substrate. Furthermore, as-formed NiAl-LDH film showed good catalytic activity for the growth of uniform carbon nanofibers with the width of about 200 nm by catalytic chemical vapor deposition of acetylene. The findings in this work are meaningful in understanding the fabrication process of architectures of layered materials on plane substrates and may provide a feasible approach for the control of the microstructure of other functional LDH films.