Preparation and photocatalytic performance of NaF–TiO₂/rGO with facet synergy

TiO₂ has been widely studied because of its excellent photocatalytic properties but still has defects, such as the short lifetime of the photogenerated carrier. To solve these problems, a novel NaF–TiO₂/rGO composite has been successfully synthesized using the hydrothermal method. The photocatalyst complexes were characterized using transmission electron microscope (TEM), energy dispersive spectrometer (EDS), diffraction of X-rays (XRD), photoluminescence spectroscopy (PL), and ultraviolet–visible spectroscopy (UV–Vis). This paper investigates the effects of hydrothermal temperature, hydrothermal time, rGO content, and NaF content on the photocatalytic activity of the NaF–TiO₂/rGO composite, and the photocatalytic activity is evaluated using the photocatalytic degradation of RhB under fluorescent lamp illumination for approximately 80 min. The TEM analysis and identification results indicate that rGO can be incorporated into TiO₂ to form a heterogeneous structure. The XRD results show that no heterophase formation occurs in the prepared NaF – TiO₂/rGO composite, and the NaF – TiO₂/rGO composite on the rGO surface does not cause the crystal shape change of the anatase phase. The PL results indicate that the main products are TiO₂ with 001 and 101 facet synergy, and adding rGO effectively reduces the electron–hole pair recombination rate. The UV–Vis results show that the band gap energy of TiO₂ is reduced by introducing NaF and further reduced after rGO is combined, thereby enhancing the photocatalytic activity and efficiency of TiO₂. Compare and analyze RhB degradation using different factor systems and determine the best synthesis process for preparing composite materials at a hydrothermal temperature of 100 ℃, a hydrothermal time of 10 h, an rGO content of 0.3%, and a NaF content of 30%. The composite material had the best photocatalytic activity. The photocatalytic test results indicate that NaF–TiO₂/rGO synthesized using the hydrothermal method has a better light absorption efficiency. The samples have a better RhB degradation rate under simulated solar irradiation. The RhB degradation followed pseudo-first-order reaction kinetics with a rate constant of 0.0448 min⁻¹, which is 1.67 times that of NaF–TiO₂. The RhB degradation rate over 80 min reached 99.8%, increasing first and then remaining constant with increasing NaF–TiO₂/rGO dosage. Additionally, NaF–TiO₂/rGO has good catalytic activity in the pH range of 3−11. The results of free radical capture showed that all three kinds of free radicals participated in RhB photocatalytic degradation, and the main active species in the reaction system should be ·OH and h⁺.