Figure 2.

Chemical and structural characterizations of catalyst materials derived from Pt/NiNC before and after annealing treatment. a) XRD patterns of NiNC support, pristine Pt/NiNC and annealed PtNi/NiNC materials. Blue arrows indicate the shift of Pt peaks before and after annealing treatment. Standard patterns of Pt (blue lines, PDF No. 00‐004‐0802) and Ni (red lines, PDF No. 99‐000‐2639) are also shown. b) Change of Ni/Pt atomic ratio versus the annealing time in hours. By normalizing the total integral areas of Ni 2p and Pt 4f regions to their corresponding relative sensitivity factors (RSFs), the Ni/Pt atomic ratios were obtained from XPS spectra. c) Ni 2p and d) Pt 4f XPS spectra of pristine Pt/NiNC and annealed PtNi _x /NiNC, together with Pt/Vul‐C reference material. XPS fitting was carried out by using CASA XPS software. For Pt⁰ species, asymmetric line shape of LA (1.2, 85, 70) was used, whereas for Pt²⁺ species, line shape of GL (30) was chosen. These vertical dashed lines are present as a guide for eyes.