Structural and Electrocatalytic Properties of Platinum and Platinum-Carbon Layers Obtained by Magnetron-Ion Sputtering

Olga Alekseeva,Vladimir Fateev,Boris Shapir,Artem Mikhalev,Elena Lutikova,Mikhail Presnyakov,Sergey Grigoriev,Vladimir Porembsky

doi:10.3390/catal8120665

Abstract

This article is devoted to further development of magnetron sputtering technology for catalysts and catalysts layer production for fuel cells and other electrochemical devices. Platinum-carbon films with Pt content up to 95–97 wt % were deposited using different sputtering regimes—DC (direct current) sputtering with and without application of a pulse negative bias voltage to the titanium substrate and also bipolar pulse sputtering with frequency of 10 kHz and 100 kHz. Composite platinum carbon targets were used for sputtering. Characteristics of platinum-carbon films were compared with those of platinum films deposited using the same regimes. The main methods of investigation were scanning transmission electron microscopy (STEM) with energy dispersive X-ray spectroscopy; potentiostatic and potentiodynamic methods. The catalytic activity of platinum-carbon films increased with platinum content and at a platinum concentration of 95–97 wt % became higher than that of platinum films sputtered in the same regimes. It was proposed that carbon atoms deposited on the substrate limited the mobility of the deposited platinum species and inhibited Pt cluster growth. Platinum-carbon films produced by pulsed DC magnetron sputtering with pulsed frequency 100 kHz consisted of narrow Pt columns with dome nanotops forming a well-developed surface. The porosity and specific surface of these columnar nanopillar films were higher compared with those of pure platinum films deposited under the same conditions. Moreover, the platinum-carbon films deposited using a bipolar pulse regime with a frequency of 100 kHz had the highest specific surface, porosity (30%) and catalytic activity in hydrogen and oxygen evolution due to a high ion current density and reduced pulse duration which inhibited the growth of large platinum globules.

Highlights

Reduction of precious metal loading is the important requirement for catalysts and catalyst layers production technology
A substantial difference in the structures and properties of the films obtained by DC sputtering without and with negative bias voltage applied to the titanium substrate is the denser structure of the latter ones
Parameters of the films obtained by pulse sputtering with 10 kHz frequency have intermediate values with respect to parameters of the films obtained by DC sputtering without and with negative bias voltage applied to the titanium substrate

Summary

Introduction

Reduction of precious metal loading is the important requirement for catalysts and catalyst layers production technology. Various methods resulting in significant surface area development and formation of active sites in the surface layer, and not in the entire volume of the carrier are used for this purpose [1,2,3,4,5,6]. Magnetron sputtering is a very efficient and environmentally friendly method which allows the controlled deposition of small amounts of metals, alloys, oxides, etc. On different substrates (including dispersed carriers) [4,5,6,7]. We used DC magnetron sputtering for the production of different active catalysts: surface. Powders and granules of different composition, carbon fibers, and fabrics were used as carriers

Methods

Results

Discussion

Conclusion