*3.2. Synthesis of Photocatalysts*

The TiO2/hectorite nanocomposites were prepared through the one-pot hydrothermal method. First, a certain amount of LiF was added into 200 mL of distilled water with stirring to obtain an LiF dispersion. Secondly, a certain amount of MgSO4 was dissolved in 100 mL of distilled water, adding sodium hydroxide solution to obtain Mg(OH)2 precipitation. Then, the Mg(OH)2 was transferred to the LiF dispersion and stirred to form a uniform mixed slurry after being filtered and washed with deionized water. Subsequently, 18.46 g of sodium silicate (SiO2 26% wt, Na2O 8.2% wt) was added into 100 mL of distilled water with the dripping of hydrochloric acid to obtain SiO2. Then, the SiO2 was transferred to the Mg(OH)2 and LiF mixed slurry and stirred to form a uniform mixed slurry (A) after being filtered and washed with deionized water.

Meanwhile, 1.1295 g of TBOT was dissolved in 10 mL of anhydrous ethanol with stirring for about 30 min to obtain a light yellow solution (B). Then, the dispersion mix A and solution B were put into the hydrothermal reaction kettle and reacted at 180 ◦C for 12 h. After the hydrothermal reaction, the solution was cooled to room temperature, centrifuged, washed, dried, ground, and finally sifted through 400 mesh to obtain a TiO2/hectorite composite photocatalyst.

A starting mixture with different molar ratios of Li:Mg:Si (Si is 8) was prepared, as shown in Table 2. The five synthesized groups of catalysts were named TH-1, TH-2, TH-3, TH-4, and TH-5.


**Table 2.** The molar ratio and mass of the samples.

### *3.3. Characterizations*

The crystallinity and structure of TiO2/hectorite were obtained by the X'pert PRO Empyrean X-ray diffractometer (PANalytical, Almelo, The Netherlands) equipped with Cu-Kα radiation (λ = 0.15418 nm) at 45 kV and 40 mA. The scanning speed was 5◦/min and the scanning range of 2θ was 10–80◦. The scanning electron microscopy (SEM) images were captured by a S-4800 scanning electron microscope (Hitachi, Tokyo, Japan) with an accelerated working voltage of 5 kV. TEM images were observed using a Tecnai F20 instrument (FEI Corp, Waltham, MA, USA) at 200 kV. The FTIR spectrum of these samples was recorded with a Nicolet iS5 FTIR spectrometer (Thermo Scientific, Madison, WI, USA) from 4000 to 400 cm−1. The N2 adsorption-desorption isotherms were captured on a Micromeritics, ASAP 2460 nitrogen volumetric adsorption facility (Norcross, GA, USA) at liquid nitrogen temperature (77 K). The specific surface area and pore size were calculated by the Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda methods, respectively. Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were recorded by using a UV-3600 spectrophotometer (Shimadzu, Tokyo, Japan) equipped with an integrating sphere, and BaSO4 was used as the reference standard. X-ray photoelectron spectroscopy (XPS) was measured on a Thermo Scientific K-Alpha electron spectrometer (Thermo Fisher Scientific, Hillsboro, OR, USA) by using 12 kV Al-Kα X-ray radiation.
