Novel NiVFeO nanocrystals: Exploring physical properties and sustainable sunlight-driven photocatalytic degradation efficiency of organic pollutants

The design of broad-spectrum nanocatalysts is an essential issue in making more efficient use of solar energy. The low-cost coprecipitation route was applied to synthesize pure NiO and two different Ni_{1-x + y}V_xFe_yO (x, y = 0.015 or 0.025) powders at a calcination temperature of 500 °C. Herein, the newly synthesized Ni_0.95V_0.025Fe_0.025O nanowires exhibited stable and high removal properties toward methyl green (MG), reactive red 120 (RR120), and ibuprofen contaminants under irradiation by solar energy. Besides, Ni_0.97V_0.015Fe_0.015O composition realized a giant dielectric permittivity. Structurally, wide and intense X-ray diffraction peaks indexed to the cubic phase of nickel oxide (NiO) semiconductor were found. The transmission electron microscope (TEM) images showed the formation of nanowire particles for Ni_0.97V_0.015Fe_0.015O and Ni_0.95V_0.025Fe_0.025O powders, while the pure sample revealed a spherical nanoparticle. The X-ray photoelectron (XPS) of Ni_0.95V_0.025Fe_0.025O powder confirmed the +3 and + 4 oxidation states for V dopant while Fe has an oxidation state of +3. NiO sample exhibited a band gap energy of 3.4 eV, which significantly decreased to 2.98 eV and 2.64 eV after codoping by (1.5 wt% V + 1.5 wt% Fe) and (2.5 wt% V + 2.5 wt% Fe) ions, respectively. The photocatalytic study proved the high degradation properties of Ni_0.95V_0.025Fe_0.025O catalyst against methyl green, reactive red 120, and ibuprofen waste, with removal efficiencies of 98, 95, and 92.5 % within 60–90 min of sunlight irradiation. The high stability of Ni_0.95V_0.025Fe_0.025O catalyst was verified from the four repeated photocatalytic tests.