Electrochemical growth mechanism of nanoporous platinum layers

Sarmiza-Elena Stanca,Jan Dellith,Gabriel Zieger,Andreas Ihring,Heidemarie Schmidt,Markus Rettenmayr,Andreas Undisz,Oliver Vogt

doi:10.1038/s42004-021-00535-w

Abstract

Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics. Pore size distribution and localization determine its properties by a large extent. However, the pore formation mechanism during the growth of the material remains unclear. In this work we elucidate the mechanism underlying electrochemical growth of nanoporous platinum layers and its control by ionic concentration and current density during electrolysis. The electrode kinetics and reduction steps of PtCl4 on platinum electrodes are investigated by cyclic voltammetry and impedance measurements. Cyclic voltammograms show three reduction steps: two steps relate to the platinum cation reduction, and one step relates to the hydrogen reduction. Hydrogen is not involved in the reduction of PtCl4, however it enables the formation of nanopores in the layers. These findings contribute to the understanding of electrochemical growth of nanoporous platinum layers in isopropanol with thickness of 100 nm to 500 nm.

Highlights

Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics
We study the electrochemistry of platinum layers in aqueous and non-aqueous media and reveal the mechanism underlying the observed formation of micro- and nano-sized porous platinum layers on the electrodes (Fig. 1) with different surface structures
Highresolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energydispersive X-ray (EDX) diagrams recorded at different stages of the electrodeposition provide information on the layer morphology and crystallinity (Figs. 1–5)

Summary

Introduction

Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics. Hydrogen is not involved in the reduction of PtCl4, it enables the formation of nanopores in the layers These findings contribute to the understanding of electrochemical growth of nanoporous platinum layers in isopropanol with thickness of 100 nm to 500 nm. We study the electrochemistry of platinum layers in aqueous and non-aqueous media and reveal the mechanism underlying the observed formation of micro- and nano-sized porous platinum layers on the electrodes (Fig. 1) with different surface structures. We used two complementary methods, staircase and linear sweep cyclic voltammetry (CV)[8,9,10,11] and electrochemical impedance spectroscopy (EIS)[12–15], to study electrochemistry of nanoporous platinum from aqueous and from non-aqueous solutions of PtCl4 without and with additives. Presented results further elucidate the mechanism underlying electrochemical growth of nanoporous platinum layers

Methods

Discussion

Conclusion