Abstract:
In the present investigation, we have reported the surface-microstructure, chemical composition and structural characteristics of the conventionally solidified Al65Cu15Co20 and Al65Cu20Co15 decagonal quasicrystals before and after chemical leaching treatment. The surface of the polycrystalline Al–Cu–Co decagonal phase was leached with 2.5 mol of Na2CO3 solution for the duration of 0.5 h, 2 h and 8 h. The leached surface was characterized by x-ray diffraction, scanning and transmission electron microscopy techniques. The energy dispersive x-ray analysis was employed to determine the chemical composition of the leached surface. After leaching treatment, the crystallographic structure of the leached surface was found to change from the quasicrystalline phase to the crystalline phases of Cu, Co and their oxides. The formation of the skeletal structure observed at the surface was attributed to the removal of Al atoms from the lattice points of the concerned decagonal quasilattice. This skeletal structure was found to contain porosities coexisting with finely distributed nano-particles of Cu, Co and Cu2O with sizes ranging from 10 to 28 nm. The 8 h leached surface containing these skeletal features has demonstrated excellent catalytic activity for steam reforming of methanol and it has led to hydrogen production at the rate of ~200 ml/g min at the reaction temperature of 580 K. © 2020 Hydrogen Energy Publications LLC
