We investigated the electrochemical CO₂ reduction reaction (CO₂RR) properties of boron- and nitrogen-codoped diamond (BNDD) electrodes. The BNDD electrodes exhibited higher CO₂RR performance than boron-doped diamond (BDD) electrodes, indicating that the nitrogen doping can promote CO₂RR reactivity. In particular, the faradaic efficiencies of the CO₂RR 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 CO₂^•– as an initial intermediate of CO₂RR; 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 CO₂RR 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 CO₂RR, particularly at low overpotentials.

中文翻译：

---

用于提高电化学 CO2 还原反应活性的硼和氮共掺杂金刚石电极

我们研究了硼和氮共掺杂金刚石 (BNDD) 电极的电化学 CO ₂还原反应 (CO _{2 RR) 特性。}BNDD 电极表现出比掺硼金刚石 (BDD) 电极更高的 CO _{2 RR 性能，表明氮掺杂可以促进 CO 2} RR 反应性。特别是，CO ₂ RR 产品的法拉第效率，在本研究中以相对较低的负电位（−2.0 V vs Ag/AgCl）获得，使用具有高氮掺杂水平的 BNDD 电极明显更高。在这种潜力下，应该很难生成 CO ₂ ^{•–作为 CO} ₂的初始中间体回复；因此，氮掺杂通过另一条反应途径促进了中间体的生成。线性扫描伏安法表明，氮掺杂可以通过质子还原促进电极表面吸附氢原子的产生。因此，我们得出结论，氮掺杂通过氢原子在电极表面的吸附促进了CO ₂ RR的初始步骤。此外，使用各种电解质溶液的电解证实，掺杂剂对 BNDD 电极表面的影响对于 CO ₂ RR 非常重要，特别是在低过电势下。