In situ phase evolution of TiO2/Ti3C2Tx heterojunction for enhancing adsorption and photocatalytic degradation.

• In-situ solvothermal method is used for the different crystal structures of TiO 2 /Ti 3 C 2 T x. • NaBF 4 was utilized as a cosurfactant to control the in situ oxidation of Ti 3 C 2 T x by adjusting the F− concentration. • (1 0 1) and (0 0 1) TiO 2 /Ti 3 C 2 T x (1.5 mmol F−) displays a superior methylene blue degradation ratio of 97.5% in 30 min under 500 W mercury light. • The photocatalytic performance of TiO 2 /Ti 3 C 2 T x heterojunction was evaluated by decomposition of organic dyes. Constructing an exposed facet TiO 2 /Ti 3 C 2 T x heterojunction with chemical bonding (Ti–O–Ti), and its narrower band structure (2.1 eV) can enhance the separation of photoinduced electron-hole pairs. In this work, an in situ solvothermal method for controlling the oxidation of Ti 3 C 2 T x is utilized with F− (0, 0.5, 1.5, 2.5 mmol NaBF 4) as the cosurfactant, wherein the concentration of F− can adjust the percentages of (1 0 1) and (0 0 1) TiO 2 which are embedded in the layers of Ti 3 C 2 T x. When the cosurfactant is 1.5 mmol F−, (1 0 1) and (0 0 1) TiO 2 /Ti 3 C 2 T x (TT-15) heterojunction to adsorb and photo-catalytically degrade organic dyes. The specific surface area of TT-15 heterojunction is 108.37 m2·g−1, which is effective in increasing the interfacial area between the organic dyes and the photocatalyst. The photocatalytic degradation efficiencies of methylene blue (MB) and methyl orange (MO) of TT-15 exceed 97.5% and 79.5% under 500 W mercury light in 30 min, and the kinetic constants of MB and MO degradation reached 0.10711 min−1 and 0.04537 min−1, respectively. Furthermore, there is a synergistic effect between the exposed facet TiO 2 /Ti 3 C 2 T x heterojunction and the photocatalytic reaction, as demonstrated by the transfer of photogenerated carriers and the generation of ·O 2 − and ·OH, which can improve the performance of the catalytic degradation of organic dyes. [ABSTRACT FROM AUTHOR]