Promoted photocatalytic activity of ZnO/Fe.Ni-MOF nanocomposites for effective removal of water pollutants upon visible light

To mitigate environmental crisis and energy shortage, heterogeneous photocatalysis has emerged as a promising method for energy conversion and water detoxification. In this study, bimetallic Fe.Ni-MOF particles were deposited on ZnO using a single-step hydrothermal synthesis route. Various analyses, including XRD, XPS, FTIR, PL, EDX, FESEM, HRTEM, EIS, UV–vis DRS, and BET were performed to study the chemical and physical properties of the synthesized nanocomposites. Photocatalytic degradation experiments indicated that the ZnO/Fe.Ni-MOF (10%) (10 wt% Fe.Ni-MOF loading on ZnO) achieved a degradation efficiency of 98% within 60 min, and its degradation rate was 53.0 times higher than that of pure ZnO for tetracycline (TC) removal. Furthermore, ZnO/Fe.Ni-MOF (10%) nanocomposite showed high ability in the degradation of amoxicillin (AMX), cephalexin (CFX), azithromycin (Azi), rhodamine B (RhB), methylene blue (MB), and malachite green (MG), indicating broad photocatalytic performance in the removal of various persistent pollutants. The ZnO/Fe.Ni-MOF (10%) nanocomposite illustrated 4.68, 7.80, 7.14, 13.7, 6.65, and 15.8 times better activity than pure ZnO in the degradation of AMX, CFX, Azi, RhB, MB, and MG pollutants, respectively. Photoluminescence spectroscopy and EIS experiments demonstrated enhanced charge transfer and significantly reduced charge recombination in ZnO/Fe.Ni-MOF (10%) nanocomposite. Recycling studies illustrated that the stability of ZnO/Fe.Ni-MOF (10%) nanocomposite was well maintained after ten reuse cycles. Additionally, the biocompatibility of the solution was confirmed through the growth of wheat grains after TC degradation. Finally, an n-n heterojunction charge separation mechanism was suggested to explain the improved activity of ZnO/Fe.Ni-MOF photocatalysts.