Critical Role of Screw Dislocation in the Growth of Co(OH)2 Nanowires as Intermediates for Co3O4 Nanowire Growth

In our prior studies, we reported the growth of Co3O4 nanowire arrays via the ammoniaevaporation-induced growth in solution and their promising applications in a Li-ion battery and oxygen evolution. Although we had identified that the growth of Co3O4 nanowire went through the beta-Co(OH)(2) intermediate, the growth mechanism of Co(OH)(2) nanowire was still elusive. The problem seemed to be rooted in its layered brucite crystal structure, which was not previously known to grow one-dimensionally (1D) perpendicular.to the layers. In this paper, we present our recent discovery that axial screw dislocation is responsible for such longitudinal growth. Through bright-field transmission electron microscope (TEm) characterizations, the screw dislocation was directly observed as a dark-contrasted line along Co(OH)(2) nanowires. Emergent spiral growth steps provide active sites For immediate adsorption of incoming molecules, resulting in a fast spiral advance rate along the e-axis or the brucite crystal. This st udy shows a new example oft he screw-dislocation driven growth or ID nanostructu res.