Doping Ag/AgCl in zeolitic imidazolate framework-8 (ZIF-8) to enhance the performance of photodegradation of methylene blue.

In this work, zeolitic imidazolate framework-8 (ZIF-8) was successfully synthesized by a facile reaction via water and alcohol solvents at room temperature. Additionally, Ag/AgCl@ZIF-8 was successfully fabricated by doping Ag/AgCl onto ZIF-8, which were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), along with UV-visible diffuse reflectance spectra (UV-vis DRS). The Ag/AgCl@ZIF-8 nanoparticles exhibited high photocatalytic activity, durability, and efficiency for the degradation of methylene blue dye (MB). The results illustrate that the band gap of Ag/AgCl@ZIF-8 is lower than that of ZIF-8, which explains the enhancement of MB degradation under UV light irradiation. The conditions affecting the photocatalytic degradation, including the dosage of photocatalyst, the initial concentration of MB, pH value, and hardness of water were systematically evaluated. In addition, the photocatalytic mechanism was explored by three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy, the effect of ZnO to photocatalytic activity was excluded, and a possible pathway of MB degradation was proposed by analysis of intermediates via liquid chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). The high photocatalytic ability of Ag/AgCl@ZIF-8 shows great application potential for the oxidation of organic pollutants in water.