Non-oxidized bare copper nanoparticles with surface excess electrons in air

Kyungwha Chung, Joonho Bang, Athira Thacharon, Hyun Yong Song, Se Hwang Kang, Woo Sung Jang, Neha Dhull, Dinesh Thapa, C. Muhammed Ajmal, Bumsub Song, Sung Gyu Lee, Zhen Wang, Albina Jetybayeva, Seungbum Hong, Kyu Hyoung Lee, Eun Jin Cho, Seunghyun Baik, Sang Ho Oh, Young Min Kim, Young Hee LeeSeong Gon Kim, Sung Wng Kim

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Copper (Cu) nanoparticles (NPs) have received extensive interest owing to their advantageous properties compared with their bulk counterparts. Although the natural oxidation of Cu NPs can be alleviated by passivating the surfaces with additional moieties, obtaining non-oxidized bare Cu NPs in air remains challenging. Here we report that bare Cu NPs with surface excess electrons retain their non-oxidized state over several months in ambient air. Cu NPs grown on an electride support with excellent electron transfer ability are encapsulated by the surface-accumulated excess electrons, exhibiting an ultralow work function of ~3.2 eV. Atomic-scale structural and chemical analyses confirm the absence of Cu oxide moiety at the outermost surface of air-exposed bare Cu NPs. Theoretical energetics clarify that the surface-accumulated excess electrons suppress the oxygen adsorption and consequently prohibit the infiltration of oxygen into the Cu lattice, provoking the endothermic reaction for oxidation process. Our results will further stimulate the practical use of metal NPs in versatile applications.

Original languageEnglish
Pages (from-to)285-291
Number of pages7
JournalNature Nanotechnology
Issue number3
Publication statusPublished - 2022 Mar

Bibliographical note

Funding Information:
This work was supported by the Creative Electride Center funded by the National Research Foundation of Korea (NRF) grant of the Korean Government (2015M3D1A1070639), by the Basic Science research programme funded by the Ministry of Education of the Korean Government (2021R1A6A1A03039696), by the Institute for Basic Science (IBS-R011-D1) and the Advanced Facility Center for Quantum Technology. KPFM measurements were supported by the Wearable Platform Materials Technology Center funded by the NRF grant of the Korean Government (2016R1A5A1009926). We thank J.-G. Kim for providing the circular FFT script and M. Yoon for assistance on the theoretical works.

Publisher Copyright:
© 2022, The Author(s).

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering
  • Materials Science(all)
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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