Synthesis and Characterization of Nanocrystalline Boron-Doped Diamond Electrodes: Towards Electrochemical Reduction of CO2

Abstract

The continuous increase of atmospheric carbon dioxide (CO2) concentration along with pollution of waters by organic wastes have led the scientific community to investigate novel strategies to address these worldwide environmental problem. Electrochemical methods are a promising approach to convert CO2 into a variety of useful chemicals and to remove contaminants from wastewater [1,2]. Nevertheless, it is necessary to develop inexpensive and chemically robust electrodes with long life-time in harsh electrochemical conditions for these processes to be efficient and economically viable.Boron-doped diamond (BDD) has been recently shown to be a promising material for electrochemical reduction of CO2 into formic acid and formaldehyde [3]. In contrast to thick microcrystalline BDD films, thin nanocrystalline BDD layers (thickness of 100 - 500 nm) provide a higher degree of flexibility in material properties, e.g. due to a variable diamond/non-diamond content, and allows efficient bottom-up nanostructuring, e.g. BDD growth on porous templates [4].In this work, we investigate nanocrystalline boron-doped diamond and composite BDD/SiC electrodes synthesized via microwave plasma enhanced chemical vapor deposition (MW PE CVD) method at different deposition temperatures (250 - 750°C) towards electrochemical reduction of CO2 in water-based electrolytes [5]. Fabricated electrodes were characterized by a variety of techniques, including Raman spectroscopy, scanning electron microscopy imaging and electrical conductivity measurements. Electrochemical properties of nanocrystalline BDD electrodes of various thickness, boron content and electrical conductivity were studied.This work has been supported by the Grant Agency of the Czech Republic (GACR) contract 19-09784Y.[1] I. Sirés et al., Environ Sci Pollut Res (2014) 21: 8336.[2] A. Goeppert et al., Chem. Soc. Rev. (2014), 43, 7995-8048.[3] K. Nakata et al., Angew. Chem. Int. Ed. (2014), 53, 871 –874.[4] V Petrák et al., Carbon (2017), 114, 457.[5] A. Taylor et al., J. Alloys. Compd., (2019) 800, 327-333