Enhanced photocatalytic Activity of Ferromagnetic Fe-doped NiO nanoparticles

The Ni1-xFexO (x = 0.00, 0.02, 0.04, 0.06 and 0.08) nanoparticles (NPs) has been synthesized via composite hydroxide mediated (CHM) synthesis approach. The single phase formation of NiO NPs was achieved without any impurity phase confirmed by XRD and average crystallite size showed minor decreasing trend with increasing Fe doping concentration. FTIR spectra showed dip in 417-432 cm(-1) range which confirmed the existence of Ni-O bonding. In Raman spectra, the weak two-magnon (2 M) band at 1472 cm(-1) in pure NiO NPs indicate suppressed anti-ferromagnetism (AFM) due to smaller average crystallite size and superparamagnetic contribution from the uncompensated surface/core spins. The absence of 2 M band in Fe doped samples is due to onset of ferromagnetism in these NPs. The M-H loops showed the room temperature ferromagnetism in Fe doped samples due to double exchange interaction of mixed valance states of Fe. The energy band gap showed minor increasing trend with increasing Fe doping concentration and is mainly attributed to Moss-Burstein effect. The photocatalytic activity showed an increasing trend with increasing Fe doping due to generation oxygen vacancies which served as energy traps and restricted the electron-hole recombination. Therefore, the bifunctional ferromagnetic Fe doped NiO NPs are more favourable for photocatalysis along with their ability of collection for re-use in the degradation process.