Electrodeposition of cobalt films with an oriented fir tree-like morphology with adjustable wetting properties using a self-assembled gold nanoparticle modified HOPG electrode

Different cobalt (Co) particle morphologies assembled in various structures were obtained by combining an electrochemical deposition process and a self-assembled gold nanoparticle (Au NP) modified highly oriented pyrolytic graphite (HOPG) electrode. Well oriented Co fir trees were formed perpendicular to the Au NP modified electrode surface, whereas a Co nanosheet flower structure grows on bare HOPG. The growth mechanisms behind the formation of such morphologies and assembled structures were discussed in terms of diffusion limited aggregation and a NP mediated growth process. The wettability of prepared cobalt films was investigated and correlated with their surface structure. Adjustability of the observed wetting properties was achieved through the tuning of electrodeposition time.