In Situ Growth of NiFe-LDH/ZIF-7 Composite With Boosted Photocatalytic Efficiency for Methyl Orange Removal

Fabricating cost-effective and efficient photocatalytic materials for the degradation of organic pollutants is a significant challenge due to the intrinsic limitations of conventional photocatalysts. The present work describes a nanoporous NiFe layered double hydroxide/ZIF-7 (NiFe-LDH/ZIF-7) heterojunction photocatalyst that was successfully synthesized using a facile in-situ two-step hydrothermal method, to offer a promising solution to these limitations. The synthesis and the incorporation of NiFe-LDH to the ZIF-7 framework were affirmed by comprehensive structural and morphological characterizations, x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The photocatalytic activity of the NiFe-LDH/ZIF-7 composite was appraised with methyl orange (MO) dye degradation as a test pollutant at exposure to natural sunlight radiation. The synthesized composite provided a remarkable degradation performance of 93.9% in 100 min with the pseuodo-first-order rate constant of 0.03 min⁻¹, which was much better than pristine ZIF-7. NiFe-LDH/ZIF-7 showed excellent reusability with 85.3% efficiency after four cycles, and trapping experiments revealed superoxide radicals as the dominant species. The synergistic effect between NiFe-LDH and ZIF-7 components is related to the enhanced activity because it offers an effective photogenerated charge separation and creates a path for reactive species. This work not only reports high photocatalytic activities of NiFe-LDH/ZIF-7, but also provides a stimulus to the design of high-performance photocatalysts that have a high surface area to treat the wastewater.