An insight into synergistic effects of Cu and Ag co-doping in nanocrystalline MgFe2O4 for enhancing the photocatalytic degradation of crystal violet and benzimidazole

Herein, the optical bandgap of magnetically separable, reusable and visible light active photocatalyst i.e. soft and n- type spinel ferrite MgFe2O4 is tailored to enhance its catalytic efficacy. The un-doped spinel ferrite MgFe2O4, and doped spinel MgFe2O4 i.e. Cu@MgFe2O4 (Cu0.05Mg0.95Fe2O4), Ag@MgFe2O4 (Ag0.1MgFe1.9O4), and Cu/Ag@MgFe2O4 (Cu0.05Ag0.1Mg0.95Fe1.9O4) were prepared by facile co-precipitation technique. Powder X-ray Diffraction (PXRD) and Fourier Transform Infrared (FTIR) spectroscopy were performed to confirm the successful synthesis of all prepared materials. The fabricated samples were used as photocatalysts for the degradation of Crystal violet (azo dye) and Benzimidazole (colorless pollutant). The results of photocatalytic experiment obtained from UV-Visible analysis showed about 71 %, 82 %, 85 %, and 93 % degradation of crystal violet by MgFe2O4, Cu@MgFe2O4, Ag@MgFe2O4, and Cu/Ag@MgFe2O4 respectively. Hence, the transition metal (Cu) and noble metal (Ag) co-doped MgFe2O4 exhibited about 22 % increase in its catalytic activity against crystal violet as compared to pure MgFe2O4. The highest catalytic performance of Cu/Ag@MgFe2O4 could be assigned to its decreased crystallite size (18 nm) and moderate band gap (2.17 eV) as compared to its counter parts i.e. MgFe2O4 (26 nm, 2.0 eV), Cu@MgFe2O4 (22.5 nm, 2.03 eV), and Ag@MgFe2O4 (21 nm, 2.05 eV). Furthermore, similar to 84 % degradation of benzimidazole was observed using Cu/Ag@MgFe2O4 as catalyst. The enhanced degradation activity of Cu/Ag@MgFe2O4 (Cu0.05Ag0.1Mg0.95Fe1.9O4) photocatalyst for both dye and colorless compound could be accredited to the synergistic effects of structural engineering and optical bandgap tuning by the co-doping of Cu and Ag in MgFe2O4. Hence, Cu0.05Ag0.1Mg0.95Fe1.9O4 could be a remarkable photocatalyst in future for the removal of harmful industrial pollutants.