Surface morphology-assisted electrochemical conversion of carbon dioxide to formic acid via nanocrystalline boron-doped diamond electrodes

Due to its unmatched corrosion stability and overall versatility, boron-doped diamond (BDD) has superb potential as an electrode material for the production of valuable chemicals via electrochemical reduction of carbon dioxide (CO2). To advance its practical application, it is necessary to explore ways to achieve cost-effective fabrication of BDD electrodes, which can enable significant selectivity for product formation during CO2 electroreduction. Here, BDD electrodes of nanocrystalline form were fabricated employing two distinct chemical vapor deposition (CVD) techniques, which allow for substantial upscaling of electrode dimensions to match industrial/wafer-size standards. Thin (<400 nm) nanocrystalline BDD layers were fabricated at various synthesis temperatures to investigate its effect on the electrical, structural, and electrochemical characteristics. Furthermore, modification of the BDD layer crystallinity and morphology has been performed to significantly alter the overall electrode structure and sp(3)/sp(2)-carbon phase-composition. Finally, when employed as cathodes in electrochemical CO2 reduction, nanocrystalline BDD electrodes of modified structure demonstrated enhanced values of faradaic efficiency (FE) towards production of formic acid (HCOOH), surpassing FEHCOOH values observed for microcrystalline form of BDD cathodes. Reported findings present a basis for further development of BDD cathodes, including their design, structure, and composition, which leverages the advantages of scalable and cost-effective synthesis of BDD electrodes.

Automated summary

This study investigates the potential application of nanocrystalline boron-doped diamond (BDD) electrodes in electrochemical reduction of carbon dioxide (CO2). The BDD electrodes were fabricated using two different chemical vapor deposition (CVD) techniques and their electrical, structural, and electrochemical characteristics were studied. Modification of the BDD layer crystallinity and morphology significantly altered the overall electrode structure and improved the selectivity of product formation during CO2 electroreduction. The nanocrystalline BDD electrodes with modified structure demonstrated higher faradaic efficiency towards the production of formic acid (HCOOH) compared to microcrystalline BDD cathodes. The findings provide a basis for further development of BDD electrodes with scalable and cost-effective synthesis.