Herein, a facile seed-assisted strategy for preparing Cu nanoparticles (NPs) with polyvinyl pyrrolidone (PVP) capping is presented. Compared to the Cu NPs with deficient PVP protection, the Cu NPs capped with a sufficient amount of PVP remain almost completely as Cu⁰ species. In contrast, the Cu NPs that are considered PVP deficient form an oxide structure in which the inner layer is face-centered cubic Cu and the outer layer is, at least in part, made up of Cu₂O species. Furthermore, to eliminate CO₂ molecule diffusion and simultaneously obtain significant current density (200 mA cm⁻²) for industrial applications, a flow cell configuration is used for carbon dioxide electro reduction reaction (CO₂RR) testing in 0.5 m potassium hydroxide solution. The Cu NPs with zero valence deliver Faradaic efficiencies (FEs) for the CO₂ reduction to CH₄ of over 70%, with a current density exceeding 200 mA cm⁻², outstripping the performances of the majority of the reported CO₂ electrocatalysts. Interestingly, the distribution of products catalyzed by the Cu NPs with +1 valence includes multicarbon products (C₂₊) such as C₂H₄, C₂H₅OH, CH₃COOH, and C₃H₇OH with combined FEs of >80%, with current densities of up to 300 mA cm⁻². The above results unambiguously establish that surface oxidation of Cu species plays a crucial role in the CO₂RR.

中文翻译：

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操纵 Cu 纳米颗粒表面氧化状态调节 CO2 电还原中对 CH4 或 C2+ 产物的催化选择性

在此，提出了一种用聚乙烯吡咯烷酮 (PVP) 封端制备铜纳米粒子 (NPs) 的简便种子辅助策略。与缺乏 PVP 保护的 Cu NPs 相比，用足够量的 PVP 覆盖的 Cu NPs 几乎完全保持为 Cu ⁰物种。相反，被认为缺乏 PVP 的 Cu NPs 形成氧化物结构，其中内层是面心立方 Cu，外层至少部分由 Cu ₂ O 物质组成。此外，为了消除 CO ₂分子扩散并同时为工业应用获得显着的电流密度 (200 mA cm ^-2 )，流动池配置用于二氧化碳电还原反应 (CO ₂RR) 在 0.5 m 氢氧化钾溶液中测试 。具有零价态的 Cu NP 将 CO ₂还原为 CH ₄的法拉第效率 (FE)超过 70%，电流密度超过 200 mA cm ^-2，超过了大多数报道的 CO ₂电催化剂的性能。有趣的是，由具有+ 1 价的 Cu NPs 催化的产物的分布包括多碳产物 (C ₂₊ )，例如 C ₂ H ₄、C ₂ H ₅ OH、CH ₃ COOH 和 C ₃ H ₇ OH 与组合的 FEs> 80%，电流密度高达 300 mA cm ^-2。上述结果明确表明，Cu 物质的表面氧化在 CO ₂ RR 中起着至关重要的作用。