High-Temperature Oxidation of Heavy Boron-Doped Diamond Electrodes: Microstructural and Electrochemical Performance Modification.

Jacek Ryl,Kazimierz Darowicki,Mateusz Ficek,Artur Zielinski,Robert Bogdanowicz,Mateusz Cieslik,Bartlomiej Dec

doi:10.3390/ma13040964

Jacek Ryl, Kazimierz Darowicki + Show 5 more

Open Access

https://doi.org/10.3390/ma13040964

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Journal: Materials	Publication Date: Feb 21, 2020
Citations: 14	License type: CC BY 4.0

Affiliation: Gdańsk University of Technology

Abstract

In this work, we reveal in detail the effects of high-temperature treatment in air at 600 °C on the microstructure as well as the physico-chemical and electrochemical properties of boron-doped diamond (BDD) electrodes. The thermal treatment of freshly grown BDD electrodes was applied, resulting in permanent structural modifications of surface depending on the exposure time. High temperature affects material corrosion, inducing crystal defects. The oxidized BDD surfaces were studied by means of cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM), revealing a significant decrease in the electrode activity and local heterogeneity of areas owing to various standard rate constants. This effect was correlated with a resultant increase of surface resistance heterogeneity by scanning spreading resistance microscopy (SSRM). The X-ray photoelectron spectroscopy (XPS) confirmed the rate and heterogeneity of the oxidation process, revealing hydroxyl species to be dominant on the electrode surface. Morphological tests using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that prolonged durations of high-temperature treatment lead not only to surface oxidation but also to irreversible structural defects in the form of etch pits. Our results show that even subsequent electrode rehydrogenation in plasma is not sufficient to reverse this surface oxidation in terms of electrochemical and physico-chemical properties, and the nature of high-temperature corrosion of BDD electrodes should be considered irreversible.

Highlights

Boron-doped diamond (BDD) surfaces are widely studied due to their unique electrochemical and physico-chemical properties [1]
The relatively high thermal conductivity coefficient (~700 W/mK) of boron-doped diamond (BDD) allows for its use as a heat spreader, replacing the commonly used metal spreaders such as copper, copper/refractory, or copper laminate in high power RF/microwave devices resulting in higher isolation of the ground plane at below 1.5 GHz [9,10]
In light of the above presented discussion, the aim of this work was to present the effect of high-temperature treatment in air at 600 ◦ C on the utility properties of boron-doped diamond electrodes, in particular for electrochemical applications

Summary

Introduction

Boron-doped diamond (BDD) surfaces are widely studied due to their unique electrochemical and physico-chemical properties [1]. The electrically conductive nanocrystalline boron-doped diamond (BDD) layers can be applied as a protective coating of Si photoelectrodes in sun-driven photoelectrochemical cells in aqueous electrolyte solutions [6]. Wastewater treatment with advanced oxidation processes at BDD usually strongly depends on the potentials and current densities. The relatively high thermal conductivity coefficient (~700 W/mK) of BDD allows for its use as a heat spreader, replacing the commonly used metal spreaders such as copper, copper/refractory, or copper laminate in high power RF/microwave devices resulting in higher isolation of the ground plane at below 1.5 GHz [9,10]

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