Selective synthesis of Ni12P5 and Ni2P nanoparticles: Electronic structures, magnetic and optical properties

Nickel phosphide particles (Ni12P5 and Ni2P) of about 10 nm were successfully synthesized by a solvothermal route through controlling reaction time, and their chemical and atomic structure, magnetic and optical properties were respectively investigated through X-ray diffraction (XRD), transmission electron microscope (TEM), Vibration sample magnetometer (VSM) and UV–visible absorption spectra (UV–Vis). Furthermore, First-principles calculations based on density functional theory were used to conduct for systematically understanding the differences in magnetic, optical properties, chemical and atomic structure between the two kinds of Nickel phosphide particles. Therein, the electronic structures and optical properties of Ni12P5 and Ni2P are investigated in the theoretical framework of the pseudopotential plane-wave First-principles scheme. The electronic bonding characteristics are also analyzed according to the electron localization function and electron density difference. The optical properties including energy loss function, refractive index, extinction coefficient, reflection spectrum and absorption coefficient are evaluated from the calculations of complex dielectric spectra. The quite discrepant crystalline structures of two nickel phosphides lead to semi-metal and semiconductor band structures, respectively resulting in the continuous and cut-off characteristics of optical transition spectra and photocatalytic properties. The present results show that the nickel phosphides with different crystalline structures have different optical properties.