Porous nitrogen-doped TiO2/graphene oxide derived from H2N-MIL-125(Ti)/graphene oxide composites as highly efficient visible light active photocatalysts for the degradation of dyes and carbamazepine

Due to the increasing release of pollutants in the environment, the development of efficient photocatalysts has become a major issue for water decontamination. Herein, heterostructured photocatalysts associating N-doped TiO 2 (N-TiO 2 ) and graphene oxide (GO) were prepared by thermolysis of the H 2 N-MIL-125(Ti) MOF combined with GO. The high porosity of H 2 N-MIL-125(Ti) is partially transferred to N-TiO 2 by calcination at 450 °C allowing the synthesis of porous N-TiO 2 /GO catalysts with a specific surface area up to 131 m 2 /g. TEM shows that N-TiO 2 /GO catalysts are composed of ca. 13 nm-sized N-TiO 2 particles deposited on GO sheets. GO not only allows to improve the light absorption in the visible range but also to enhance the charge carrier separation as demonstrated by photoluminescence and (photo)electrochemical measurements. The highest photocatalytic activity was reached for N-TiO 2 combined with 30 wt% GO and the obtained catalyst exhibits high activity for the degradation of dyes (Orange II and Eosin Y) and of the Carbamazepine drug under visible light irradiation. Radical scavenging experiments show that superoxide radicals O 2 − , holes h + and singlet oxygen 1 O 2 play a major role in the photodegradation process. The N-TiO 2 /GO(30) photocatalyst also exhibits high stability and reusability and therefore has a high potential for real environmental applications.