**4. Conclusions**

Platinum cones were fabricated by vapor deposition for cathode preparation followed by electrodeposition to PC track-etched membranes with non-penetrating conically shaped pores as templates. Conical pores with a surface diameter and depth of approximately 70–1500 nm and 0.7–11 µm, respectively, were obtained by varying the etching time and etchant concentration, thereby also enabling control of their aspect ratio and cone angle. The obtained platinum cones were found to be approximately the same size and geometry as the template pores, and they had a polycrystalline nanotip with no metal contaminants. In order to demonstrate the electrocatalytic activity, electrochemical measurements were performed for the ethanol oxidation reaction. The electrocatalytic activity of the platinum cones with a diameter of 550 nm, a length of 2.4 <sup>µ</sup>m, and an areal density of 1.0 <sup>×</sup> <sup>10</sup>8/cm<sup>2</sup> was 3.2 times higher than that of the platinum plate. The combination of ion-track etching and electrodeposition is thus an effective method for the fabrication of micro/nanocones with high electrocatalytic performance.

**Author Contributions:** Conceptualization, T.Y.; data curation, Y.S. and M.S.; investigation, Y.S.; methodology, S.-i.S., S.Y. and H.K.; project administration, T.Y.; resources, S.Y. and H.K.; supervision, T.Y.; visualization, Y.S. and S.-i.S.; writing—original draft, Y.S. and T.Y.; writing—review & editing, T.Y. and Y.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
