*Article* **One-Pot Synthesis of TiO2/Hectorite Composite and Its Photocatalytic Degradation of Methylene Blue**

**Dingqing Yang \*, Jinyang Chen \*, Xiaomin Hong, Jingying Cui and Lingzhen Li**

School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China;

hxm1102@shu.edu.cn (X.H.); qtaacui@shu.edu.cn (J.C.); 123abcabc@shu.edu.cn (L.L.)

**\*** Correspondence: ydq@shu.edu.cn (D.Y.); chenjy@shu.edu.cn (J.C.);

Tel.: +86-21-66137729 (J.C.); Fax: +86-21-66137725 (J.C.)

**Abstract:** TiO2/hectorite composite photocatalysts with different molar ratios of lithium, magnesium, and silicon were synthesized by a one-pot hydrothermal method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption isotherms, and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). When the molar ratio of lithium, magnesium, and silicon was 1.32:5.34:8 (TH-2), the composite showed the highest UV photocatalytic degradation of methylene blue (MB). The apparent rate constant of TH-2 was 0.04361 min<sup>−</sup>1, which was about 3.12 times that of EVONIK Degussa commercial TiO2 of AEROXIDE P25. The improvement of photocatalytic efficiency of the composite was mainly due to its high specific surface area, light trapping ability, and effective separation of electrons (e−) and holes (h+). At the same time, the F element of hectorite is beneficial to the formation of Ti3+ in TiO2, thus enhancing the photocatalytic activity. After five cycles, the removal rate of MB with TH-2 still reached 87.9%, indicating its excellent reusability.

**Keywords:** photocatalysis; TiO2; hectorite; one-pot synthesis; degradation of organic dyes

**Citation:** Yang, D.; Chen, J.; Hong, X.; Cui, J.; Li, L. One-Pot Synthesis of TiO2/Hectorite Composite and Its Photocatalytic Degradation of Methylene Blue. *Catalysts* **2022**, *12*, 297. https://doi.org/10.3390/ catal12030297

Academic Editor: Ewa Kowalska

Received: 25 January 2022 Accepted: 3 March 2022 Published: 6 March 2022

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