Facile synthesis of molecularly imprinted black TiO_2-x/carbon dots nanocomposite and its recognizable photocatalytic performance under visible-light

In this work, novel molecularly imprinted black TiO_2-x/CQDs (MIP-TiO_2-x/CQDs) nanocomposites are firstly synthesized using methylene blue (MB) as molecular imprinter and reducer via hydrothermal-calcination method. MB has a double effect on the formation of MIP-TiO_2-x/CQDs: Firstly, alter the morphology and structure, increasing the specific surface area and endowing the selective adsorption ability; Secondly, promote the formation of Ti³⁺ ions and oxygen vacancies, efficiently enhancing the visible light utilization and suppressing the photoelectrons-holes recombination process. The introduction of carbon quantum dots (CQDs) is icing on the cake, further extends the optical response range, hinders the electrons-holes recombination process and heightens the photocatalytic performance. Multiple characterizations have been implied to analysis the structure, composition, chemical state, optical absorption property, photochemical characteristic and photocatalystic performance of as-prepared MIP-TiO_2-x/CQDs nanocomposites. As a result, the remarkable performance of MIP-TiO_2-x/CQDs for MB degradation under visible light is attributed to the broadened light-response range due to the Ti³⁺ ions and oxygen vacancies, increased specific surface area and selective adsorption achieved by molecular imprinting, efficient photogenerated carriers’ movement thanks to the CQDs modification and synergism among Ti³⁺ ions, oxygen vacancies and Ti–OH bonds.