fig2

Figure 2. Physical characterization of prepared samples. (A) EPR image of Ni_1-xCo_xP@NC, Ni₂P@NC and CoP@NC composites. High-resolution XPS spectra of (B) Ni 2p; (C) Co 2p; (D) P 2p; (E) C 1s and (F) N 1s of Ni_1-xCo_xP@NC, Ni₂P@NC and CoP@NC samples. Ni_1-xCo_xP@NC: N-doped carbon (NC)-coated Ni_1-xCo_xP; EPR: electron paramagnetic resonance; XPS: X-ray photoelectron spectroscopy.