Strong spin-ferromagnetic order and active dyes-depollution performance of CuO semiconductor: Gd and Gd/Mn dopants

In this work, new dilute magnetic semiconductor compositions and broad spectrum photocatalysts based on Gd doped and (Gd, Mn) codoped CuO were synthesized by adapted sol gel method. The analyzed XRD peaks were completely indexed to the crystallographic planes of monoclinic copper oxide (CuO) structure. The effectual substitution of Cu²⁺-sites by Gd and (Gd, Mn) ions was verified from the expansion of the unit cell and shift of the XRD peaks. The inclusion of Gd and (Gd, Mn) ions move the band gap energy of pure CuO (1.41 eV, λ = 879 nm) to low energy region with measured values of 1.3 eV (λ = 953 nm) and 1.26 eV (λ = 984 nm), respectively. The morphological analysis illustrates that the existence of Gd and Mn ions enhances the reduction of the grains size of CuO with more distribution of fine particles. The room temperature ferromagnetic order was impressively improved after incorporation of (Gd, Mn) ions into the lattice of CuO. Herein, Cu_0.96Gd_0.02Mn_0.02O composition exhibits a high saturation magnetization of 1.21 emu/g while the coercivity and remanence values were 156 Oe and 0.15 emu/g, respectively. On the other hand, Cu_0.96Gd_0.02Mn_0.02O as a photocatalyst has large efficiencies for removal of brilliant green and Congo red under normal solar energy and Xenon photoreactor radiation. The measured photodegradation efficiency of Cu_0.96Gd_0.02Mn_0.02O catalyst was 96% and 91% during 70 min with strong stability for 4 series and high mineralization of both dyes to CO₂ and H₂O. The obtained results highlight that Cu_0.96Gd_0.02Mn_0.02O composition possesses dual-functions operation linked to spin-electronic devices and photocatalysis applications.