One-Dimensional Ni-Based Nanostructures and Their Application as Solid Oxide Fuel Cell Anodes: A DFT Investigation

Abstract

Using density functional theory methods, we investigate the relative stability of three types of 1D Ni nanostructures. The first two are conceived from the growth of either Ih or Oh symmetry 0D nanoparticles of Ni, and the third, a Ni (6,3) nanorod (NR), is a hexagonal close-packed structure (both on the surface and along the axis direction). Our calculations show that 1D Ni NRs as well as Ni double-walled and triple-walled nanotubes, are more stable than comparable-sized Ni 0D nanoparticles. We explore the potential of NRs as a prototype catalyst by calculating the alloying effect of M (M = Mo, Fe, Co, and Cu) on the adsorption of C and S under full coverage of atomic O. The calculated results suggest that Ni-based 1D NRs are highly reactive toward O-binding, an indication that anode oxidation may be achieved at much lower temperatures. By forming a NiM surface alloy, the binding strength of C and S can be reduced. In particular, Fe and Cu seem to be the most promising metal dopants in Ni-based 1D NR systems for suppressing the formation of C and S (whereas Co promotes the binding of C). Also, it is found that the Ni0.75Mo0.25 (6,3) NR model collapses its tubular structure due to strong binding with O.