The common and intrinsic skin electric-double-layer (EDL) and its bonding characteristics of nanostructures

Highlights: • An intrinsic EDL of 2.14 ± 0.01 bond-length thick exists universally to nanocrystals. • EDL bond contraction densifies and entraps core electron and energy. • Densified charge polarizes subjectively edge atoms with localized ending states. • The EDL dictates the atomic-undercoordination derivacy and size dependency. • BOLS-NEP theory reconciles intrinsically defects, surfaces, and nanostructures. We show that nanocrystals share a common and intrinsic skin electric-double-layer (EDL). The EDL is determined to be 2.14 regular-bond-length thick using differential phonon spectroscopy that distills phonon abundance transiting from the core region to the EDL of the sized crystals. Theoretical reproduction of the size-resolved Raman shift for Si, CeO₂, and SnO₂ nanocrystals, elasticity of ZnO, and the XPS 2p energy shift, band gap expansion and melting point shift of Si crystals confirmed the universality of the EDL of which bonds are shorter and stronger than those inside the bulk or the particle core interior. The EDL bond contraction and the associated electron entrapment and polarization originate, and the EDL volume quantifies the size dependency of nanostructures while the electron entrapment or polarization entitles the undercoordinated single or edge atoms with properties that a bulk does never show.