Competitive coordination strategy for preparing TiO2/C nanocomposite with adsorption-photocatalytic synergistic effect

The synergistic adsorption-photodegradation effect has been used to form TiO2-based photocatalyst but is limited by the multi-step preparation strategy. The present study employed the "one-pot " method to form the precursor via a competitive coordination strategy. Ca2+/Ti4+-alginate coordination complex was prepared and further carbonized to C-TiO2/CaCO3 nanocomposites for methylene blue (MB) removal. The resultant materials were characterized by FT-IR, XRD, XPS, UV-Vis DRS, TG-DTA, BET, and SEM-EDS techniques, and their synergistic adsorption-photodegradation performance on MB was also studied under simulated sunlight. Results indicated that the anatase-rutile phase of TiO2 in the nanocomposite transformed to the anatase phase by adding CaCl2. The C-TiO2/CaCO3 nanocomposite presented higher specific surface area, pore volume, and mean pore size and consequently showed enhanced adsorption capacity. Low bandgap energy determined an excellent photo -catalytic activity, and the degradation ratio of MB reached 96.46% within 10 min. The cycling photodegradation of MB indicated high cycling stability. The C-TiO2/CaCO3 composites made by this simple method have syner-gistic adsorption-photodegradation performance and can be reused after regeneration, opening up a sustainable opportunity for wastewater treatment.