Fabrication of Ni and Mn co-doped ZnFe2O4 spinel ferrites and their nanocomposites with rGO as an efficient photocatalyst for the remediation of organic dyes

Herein, we have synthesized Ni and Mn co-doped ZnFe 2 O 4 ferrites using the simple co-precipitation method and their nanocomposites (NCs) with 10 % rGO using the ultra-sonication route. The structural investigation revealed the successful formation of single-phase ZnFe 2 O 4 NPs with cubic spinel ferrite geometry. The crystallite size was determined to be in the range of 21 nm to 28 nm. The current–voltage (I-V) analysis revealed that Ni and Mn co-doping and the addition of rGO nanosheets in ZnFe 2 O 4 NPs boosted the electrical responses of the fabricated Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs. The BET analysis indicates an increase in the surface area of Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs (132 m 2 /g) that might be attributed to the inclusion of rGO nanosheets, which prevents the NPs from agglomeration. The photocatalytic evaluation of the pristine ZnFe 2 O 4 NPs, Ni and Mn co-doped Zn 1-x Ni x Fe 2-y Mn y O 4 NPs, and Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs photocatalysts was tested by photodegradation of malachite green (MG) dye under sunlight irradiation. Results exhibited improved photocatalytic responses and degraded 94.6 % of MG dye in 45 min using Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs, which was much higher compared to the Ni and Mn co-doped Zn 1-x Ni x Fe 2-y Mn y O 4 NPs (58.7 %) and pristine ZnFe 2 O 4 NPs (38.3 %). The increased degradation potential of Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs was accredited to the highly conducting nature and 2D nano-sheets of rGO, which efficiently inhibited the recombination of charge carrier species. Ultimately, the remarkable photocatalytic capability exhibited by Zn 1-x Ni x Fe 2-y Mn y O 4 /rGO NCs implies that the synthesized NCs could have auspicious practical applications in the elimination of dyes from wastewater.