Synergistic Charge Separation in Engineered 2D CoTiO3/TiO2 Composites for Superior Photocatalysis

The CoTiO ₃ /TiO ₂ composite material with a special nanostructure was successfully prepared using layered hydrogen titanate (HTO) as the precursor. First, HTO was pretreated with hydrogen peroxide to obtain an H ₂ O ₂ -HTO intermediate with an increased interlayer spacing. During this process, active peroxy groups were introduced into the layer plates, significantly enhancing the reaction activity of the material. Subsequently, the modified precursor was subjected to an ion-exchange reaction with (CH ₃ COO) ₂ Co·4H ₂ O solutions of different concentrations. This reaction successfully achieved the selective exchange of Co ²⁺ for H ⁺ between the layers and the subsequent topotactic transformation, ultimately yielding a CoTiO ₃ /TiO ₂ nanocomposite with a plate - like morphology. The analysis results from various characterization methods showed that HTO treated with H ₂ O ₂ could effectively increase the interlayer spacing, creating favorable conditions for metal ion exchange and ultimately leading to the successful preparation of the CoTiO ₃ /TiO ₂ composite. The study also found that the CoTiO ₃ /TiO ₂ material prepared by the H ₂ O ₂ exchange method still retained its original plate - like morphology. Using rhodamine B as the target degradation substance, the photocatalytic degradation performance of the CoTiO ₃ /TiO ₂ composite was systematically studied, and its degradation conditions were optimized. The experimental results showed that the composite exhibited the best photocatalytic degradation effect under the following conditions: using sunlight as the visible light source, a dark adsorption time of 30 min, an illumination time of 30 min, a catalyst dosage of 25 mg, a molar ratio of CoTiO ₃ to TiO ₂ of 8/2, and an initial concentration of the rhodamine B (RhB) solution of 20 mg･L ^- ¹(volume of 50 mL). In addition, the study found that, under the catalytic action of the CoTiO ₃ /TiO ₂ nanocomposite, combined with the synergistic effect of peroxymonosulfate (PMS) and visible light(VIS), the degradation efficiency of RhB was significantly higher than that in the system using PMS alone. This was mainly due to the high - energy input of the visible light source, which could excite the generation of highly oxidizing active substances on the catalyst surface, thereby accelerating the degradation process. This result confirmed that the CoTiO ₃ /TiO ₂ composite could effectively activate PMS and significantly improve the degradation efficiency. Meanwhile, the cyclic stability experiment showed that the catalyst had good reusability, providing an important basis for its application in the actual environment.