Fig. 4. (A) Geometrical structures of C6-protected Au₂₅ and PtAu₂₄ NCs (golden, gold atoms of the core; olive, gold atoms of the shell; grey, sulfur). (B) The square-wave voltammogram. (C) HER polarization curves of C6-protected Au₂₅ and PtAu₂₄ NCs. (D) High angle annular dark-field SEM (HAADF-STEM) images. (E) HER polarization curves of the C6-protected Au₂₅/MoS₂ composite. Panels (a)–(c) are reproduced with permission from ref. 29. Copyright 2017 Springer Nature. Panels (d) and (e) are reproduced with permission from ref. 33. Copyright 2017 Wiley-VCH.