We explored the size-dependent activity and selectivity of Zn nanoparticles (NPs) for the electrochemical CO2 reduction reaction (CO2RR). Zn NPs ranging from 3 to 5 nm showed high activity and selectivity (∼70%) for CO production, whereas those above 5 nm exhibited bulk-like catalytic properties. In addition, a drastic increase in hydrogen production was observed for the Zn NPs below 3 nm, which is associated with the enhanced content of low-coordinated sites on small NPs. The presence of residual cationic Zn species in the catalysts was also revealed during CO2RR via operando X-ray absorption fine-structure spectroscopy measurements. Such species are expected to play a role in the selectivity trends obtained. Our findings can serve as guidance for the development of highly active and CO-selective Zn-based catalysts for CO2RR.

中文翻译：

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CO2电还原过程中尺寸控制的Zn纳米颗粒的结构和氧化态的操作演化

我们探索了 Zn 纳米粒子 (NPs) 对电化学 CO2 还原反应 (CO2RR) 的尺寸依赖性活性和选择性。3 到 5 nm 的 Zn NPs 显示出高活性和选择性 (~70%) 的 CO 生产，而 5 nm 以上的那些表现出类似块体的催化性能。此外，观察到小于 3 nm 的 Zn NPs 的产氢量急剧增加，这与小 NPs 上低配位位点的含量增加有关。在 CO2RR 过程中，通过操作 X 射线吸收精细结构光谱测量也揭示了催化剂中残留阳离子 Zn 物质的存在。预计此类物种将在获得的选择性趋势中发挥作用。我们的研究结果可以作为开发用于 CO2RR 的高活性和 CO 选择性锌基催化剂的指导。