Fig. 1. Synthesis and physical characterization of MoNi₄ and WNi₄ alloys.

a Schematic illustration of the synthesis of MoNi₄ and WNi₄ alloys. b, e SEM images of MoNi₄ and WNi₄ alloys, respectively. Scale bars, 200 nm. Insets in b, e are photographs of MoNi₄ (2.2 g) and WNi₄ (4.0 g) alloys synthesized in one batch. c, f STEM images of MoNi₄ and WNi₄ alloys, respectively. Scale bars, 200 nm c and 50 nm f. d, g Atomic-resolution HAADF-STEM images of typical MoNi₄ and WNi₄ particles, respectively. Scale bars, 2 nm. Insets in d, g show corresponding FFT patterns. The white arrows denote atomic steps. h XRD patterns of MoNi₄, WNi₄, and freshly synthesized Ni. Insets give corresponding crystal structures. i STEM-EDX elemental mappings of MoNi₄ and WNi₄ alloys. Scale bars, 500 nm (up) and 100 nm (down).