NiFe-Layered Double Hydroxides as a Novel Hole Repository Layer for Reinforced Visible-Light Photocatalytic Activity for Degradation of Refractory Pollutants

Herein, reinforced functional catalysts, nickel-ironlayered double hydroxides/graphitic carbon nitride (NiFe-LDH/g-C3N4) hybrid composites, were fabricated successfully by coupling NiFe-LDH with mesoporous g-C3N4 microtubes spontaneously. Next, the as-prepared photocatalysts were evaluated and characterized by some advanced characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible (vis) diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and photocurrent tests. Results demonstrated that NiFe-LDH can be identified as hole repository layers, which can distinctly decrease the recombination probabilities of photogenerated electron and hole pairs, thus increasing the degradation performance. It was discovered that 96.81% of tetracycline hydrochloride (TC) (20 mg/L) was removed within 60 min when the concentration of NiFe-LDH/g-C3N4 was 0.4 g/L. Besides, NiFe-LDH/g-C3N4 can almost completely degrade the pollutants methyl orange (MO) (95.71%) and rhodamine B (RhB) (96.26%). In addition, the cycle experiment proved that NiFe-LDH/g-C3N4 possessed extraordinary reusability and photodegradation stability. Finally, a possible photocatalytic reaction mechanism was discussed, and this work would offer some insights into the design of related visible-light-induced catalysts for removal of various stubborn pollutants.