Hollow Cu2O nanoparticles (NPs) with a diameter of 7.0 ± 1.3 nm were synthesized by sputter deposition of Cu in a room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), followed by the oxidation of Cu NPs in EMI-BF4 by prompt heating at 373 K in air. The void space was 2.3 ± 0.7 nm in size, and the shell thickness was estimated to be 2.4 nm. The structure was presumably produced by the Kirkendall effect at the nanoscale. Core-shell-structured Cu@Cu2O NPs and solid Cu2O NPs were also synthesized by changing the oxidation conditions. From the action spectra of their cathodic photocurrents, the optical bandgap of the Cu2O phase in these NPs was estimated to be 2.51–2.56 eV, which is larger than that of bulk Cu2O (2.1 eV). The photoelectrochemical activities of the hollow or spherical Cu2O NPs were higher than that of the core-shell Cu@Cu2O NPs.

中文翻译：

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通过离子液体/金属溅射形状控制合成具有个位数纳米级空隙空间的 Cu2O 纳米粒子及其光电化学性能

通过在室温离子液体 (RTIL)、1-乙基-3-甲基咪唑鎓四氟硼酸盐 (EMI-BF4) 中溅射沉积 Cu，然后氧化，合成直径为 7.0 ± 1.3 nm 的空心 Cu2O 纳米粒子 (NPs) EMI-BF4 中的 Cu NPs 通过在空气中 373 K 下迅速加热。空隙空间的大小为 2.3 ± 0.7 nm，壳厚度估计为 2.4 nm。该结构可能是由纳米级的柯肯德尔效应产生的。还通过改变氧化条件合成了核壳结构的 Cu@Cu2O NPs 和固体 Cu2O NPs。从它们的阴极光电流的作用光谱来看，这些纳米颗粒中 Cu2O 相的光学带隙估计为 2.51-2.56 eV，大于块状 Cu2O（2.1 eV）的光学带隙。