Fig. 2. (A) The annular dark-field scanning transmission electron microscopy (SEM) image of ALD50Pt/nitrogen-doped graphene nanosheets (NGNs). Scale bar shows the length of 20 nm. (B) HER current density of Pt/C, ALD50Pt/NGNs and ALD100Pt/NGNs. (C) Illustration of the assembly of trigonal prismatic {Ni24} coordination cage (CIAC-121) and the fabrication of ultrafine Pt NCs. (D) The HER polarization curves. (E) Mass HER activity of Pt NCs@CIAC trigonal prismatic coordination cage ({Ni24(TC4A-SO2)6(TDC)12(H2O)6}, H4TC4A-SO2 = p-tert-butylsulfonylcalix[4]arene; H2TDC = 2,5-thiophenedicarboxylic acid). Panels (a) and (b) are reproduced with permission from ref. 24. Copyright 2016 Springer Nature. Panels (c), (d) and (e) are reproduced with permission from ref. 25. Copyright 2016 American Chemical Society.
