Intimate coupling of 3D MnFe2O4 cubes on 1D ZnO nanorods for sustainable photocatalysis under visible light: Computational analysis of reactive sites and degradation pathway

In recent times, the discharge of wastewater containing aromatic compounds has serious effects on human health and the environment. Thus the fabrication of an efficient and visible light-active nano photocatalyst offers an optimum and sustainable solution. In this study, ZnO/MnFe2O4 nanocatalyst was fabricated by the ultrasonication mediated reflux method. The fabricated nanomaterials were characterized with SEM, TEM, XRD, XPS, UV-visible DRS, BET, EIS, PL, ESR analysis. The ensued nanocomposite (NCs) was employed for the photocatalytic removal of methylene blue (MB) dye. The photocatalytic efficiency of ZnO/MnFe2O4 NCs for the removal of MB was 85% which was higher than the efficiency of both the individual semiconductors ZnO (63%) and MnFe2O4 (69%). The rate constant for the photocatalytic removal of MB by ZnO/MnFe2O4 NCs (0.07 min−1) was 12 times higher than the ZnO (0.006 min−1) and 1.75 times higher than MnFe2O4 (0.04 min−1). The boosted photocatalytic performance of ZnO/MnFe2O4 was attributed to the higher surface area (204.559 m2/g) with more active sites compared to ZnO (188.212 m2/g) and MnFe2O4 (106.893 m2/g). The as-fabricated ZnO/MnFe2O4 NCs possess excellent stability as affirmed by recycle test and the analysis of reused XRD. The major part of the degradation of MB was performed by •OH− radicals which was confirmed by scavenging test. The overall results suggest that the fabricated ZnO/MnFe2O4 is an active material for photocatalytic applications.