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 Lee, Seong‐Gon Kim, Sung Wng Kim
IF 34.9
Nature Nanotechnology
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.
