Fabrication of Size- and Shape-Controlled Platinum Cones by Ion-Track Etching and Electrodeposition Techniques for Electrocatalytic Applications

Yuma Sato,Hiroshi Koshikawa,Shin-Ichi Sawada,Masaki Sugimoto,Shunya Yamamoto,Tetsuya Yamaki

doi:10.3390/qubs5030021

Abstract

The micro/nanocone structures of noble metals play a critical role as heterogeneous electrocatalysts that provide excellent activity. We successfully fabricated platinum cones by electrodeposition using non-penetrated porous membranes as templates. This method involved the preparation of template membranes by the swift-heavy-ion irradiation of commercially available polycarbonate films and subsequent chemical etching in an aqueous NaOH solution. The surface diameter, depth, aspect ratio and cone angle of the resulting conical pores were controlled in the ranges of approximately 70–1500 nm, 0.7–11 μm, 4–12 and 5–13°, respectively, by varying the etching conditions, which finally produced size- and shape-controlled platinum cones with nanotips. In order to demonstrate the electrocatalytic activity, electrochemical measurements were performed for the ethanol oxidation reaction. The oxidation activity was found to be up to 3.2 times higher for the platinum cone arrays than for the platinum plate. Ion-track etching combined with electrodeposition has the potential to be an effective method for the fabrication of micro/nanocones with high electrocatalytic performance.

Highlights

Micro/nano-sized wire and cone structures of platinum directly integrated with a conducting substrate have several advantages for electrocatalytic performance [1,2,3]
The size and shape of the template pores were controlled by the etching time and etchant concentration, thereby enabling the preparation of platinum cones with different base diameters and lengths
We demonstrated the fabrication of platinum cones by ion-track etching and electrodeposition techniques and found them to be a promising alternative for ethanol oxidation electrocatalysts

Summary

Introduction

Micro/nano-sized wire and cone structures of platinum directly integrated with a conducting substrate have several advantages for electrocatalytic performance [1,2,3]. Electroless deposition does not require conducting substrates; the surface must be pretreated with Sn2+ , Ag, or Pd via a sensitization and activation processes [4] These metal ions and atoms are left as contaminants on the surface of the cones and affect their electrocatalytic performance [5,6] On the other hand, electrodeposition requires no pretreatment steps and enables the fabrication of metal-contaminant-free platinum cones. The size and shape of the template pores were controlled by the etching time and etchant concentration, thereby enabling the preparation of platinum cones with different base diameters and lengths We demonstrated their higher electrocatalytic activity by the electro-oxidation of ethanol

Experimental

20 PC mAfilms andwere

Results and Discussion

Conclusions