Surfactant-free synthesis of novel copper oxide (CuO) nanowire–cobalt oxide (Co3O4) nanoparticle heterostructures and their morphological control

Structural evolution of cobalt oxide–tungsten oxide nanowire heterostructures for photocatalysis

“…Tungsten was dominantly distributed in these decorating nanostructures while the original Co 3 O 4 nanowire core was chemically intact. This is consistent with the previous observations of the authors and indicates that the post-annealing process involves surface migration and recrystallization of the sputtered tungsten oxide and/or its diffusion and compositing with cobalt oxide [19,34]. Such surface migration and diffusion have been attributed to surface tension, capillary forces, and chemical potential differences between the nanowire and coatings [34].…”

“…Such underlayer formation has been confirmed previously for similar thermal growth of metal oxide nanowires on metal foils (e.g. Cu, Fe) [34,35]. The EDS analysis and elemental imaging for the formation of CoO/Co 3 O 4 film were further detailed in Fig.…”

Controlled assembly of graphene shells encapsulated gold nanoparticles and their integration with carbon nanotubes

“…The latter was a low chemical potential region as compared to curved CNT sidewalls. Similar has been observed for nanowire decoration with nanoparticles [59]. On the other hand, since the Au coating was performed on the mesh network of dispersed CNTs, Au nanoparticles must have resulted directly from the dewetting of the Au coating on the Si substrate (arrows in Figs.…”

“…Decorating nanoparticles onto the surface of high curvature substrates such as nanowires and CNTs is of interest due to their combined properties and ability to minimize nanoparticle aggregation [25,58,59]. However, certain major challenges remain such as uniform decoration of nanoparticles on CNTs without surface or chemical modification of the latter and in a dry processing route [60].…”

“…The latter could be due to two reasons: (a) Surface migration of Au from curved CNT surface to flat Si wafer and (b) dewetting of Au films coated onto the exposed regions of Si wafer that were not covered with CNTs. The first one can be attributed to the fact that Au nanoparticles favored low chemical potential regions (low curvature or flat substrate) than high chemical potential CNT surface [25,59]. These chemical potential effects must be dominant, as many CNTs were decorated with aggregated Au nanoparticles on their flat tip regions ( Fig.…”