Boron- and Nitrogen-Codoped Diamond Electrodes for the Improved Reactivity of Electrochemical CO<sub>2</sub> Reduction Reaction
Yudai Miyake, Takeshi Kondo, Atsushi Otake, Yasuaki Einaga, T Tojo, Makoto Yuasa
Abstract
High Resolution Image Download MS PowerPoint Slide We investigated the electrochemical CO 2 reduction reaction (CO 2 RR) properties of boron- and nitrogen-codoped diamond (BNDD) electrodes. The BNDD electrodes exhibited higher CO 2 RR performance than boron-doped diamond (BDD) electrodes, indicating that the nitrogen doping can promote CO 2 RR reactivity. In particular, the faradaic efficiencies of the CO 2 RR products, obtained at a relatively low negative potential (−2.0 V vs Ag/AgCl) in this study, were significantly higher using BNDD electrodes with high nitrogen-doping levels. At this potential, it should be difficult to generate CO 2 •– as an initial intermediate of CO 2 RR; therefore, nitrogen doping promoted the generation of the intermediate through another reaction pathway. Linear sweep voltammetry revealed that nitrogen doping could promote the generation of adsorbed hydrogen atoms on the electrode surface by proton reduction. Thus, we concluded that nitrogen doping promoted the initial step of CO 2 RR through the adsorption of hydrogen atoms on the electrode surface. In addition, electrolysis using various electrolyte solutions confirmed that the influence of dopants on the BNDD electrode surface was significant for CO 2 RR, particularly at low overpotentials.