fig13

Figure 13. Structural characterization of as-obtained phosphides. (A) XRD patterns of NiPx, CoPx and NiCo₂P_x. (B) SEM images. (C) Elemental mapping of P, Co, and Ni. (D) EDX spectrum. (E) HRTEM image. (F) Corresponding SAED pattern of NiCo₂P_x. HER stabilities of NiCo₂P_x. (G) Polarization curves for NiCo₂P_x before and after 5000 cycles with a scan rate of 100 mV s^-1 between +0.20 and -0.20 V. (H) Time dependence of current density for NiCo₂P_x at static overpotentials of 100 mV (in 1 M KOH and PBS) and 150 mV (in 0.5 M H₂SO₄) for 30 h. (I) SEM images and (J) XRD patterns of NiCo₂P_x NWs before and after long-time test. Reproduced with permission. Copyright 2017, Wiley^[126].