N-doped carbon (N–C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, however, the role of different functional moieties is still controversial. We have synthesized a set of N–C catalysts, with identical morphologies (∼27 nm pore size). By systematically changing the precursors, we have varied the amount and chemical nature of N-functions on the catalyst surface. The CO₂ reduction (CO₂R) properties of these catalysts were tested in both electrochemical (EC) and thermal catalytic (TC) experiments (i.e., CO₂ + H₂ reaction). CO was the major CO₂R product in all cases, while CH₄ appeared as a minor product. Importantly, the CO₂R activity changed with the chemical composition, and the activity trend was similar in the EC and TC scenarios. The activity was correlated with the amount of different N-functions, and a correlation was found for the −NO_x species. Interestingly, the amount of this species decreased radically during EC CO₂R, which was coupled with the performance decrease. The observations were rationalized by the adsorption/desorption properties of the samples, while theoretical insights indicated a similarity between the EC and TC paths.

中文翻译：

---

通过热催化和电催化对 N 掺杂碳催化剂的 CO2 转化：C-NOx 部分的作用

N掺杂碳（N-C）材料在不同的电化学和催化应用中越来越受欢迎。然而，由于这些材料的结构和化学计量多样性，不同功能部分的作用仍然存在争议。我们合成了一组具有相同形态（~27 nm 孔径）的 N-C 催化剂。通过系统地改变前体，我们改变了催化剂表面 N 官能团的数量和化学性质。在电化学（EC）和热催化（TC）实验（即CO ₂ + H ₂反应）中测试了这些催化剂的CO ₂还原（CO _{2 R）性能。}在所有情况下， CO 是主要的 CO ₂ R 产物，而 CH ₄作为次要产品出现。重要的是，CO ₂ R 活性随着化学成分的变化而变化，并且在 EC 和 TC 情景中的活性趋势相似。该活性与不同 N 功能的量相关，并且发现了与 -NO _x物种相关的相关性。有趣的是，该物种的数量在 EC CO ₂ R 期间急剧下降，同时伴随着性能下降。通过样品的吸附/解吸特性使观察结果合理化，而理论见解表明 EC 和 TC 路径之间存在相似性。