Metal-organic framework derived multi-functionalized and co-doped TiO2/C nanocomposites for excellent visible-light photocatalysis

Multi-functionalized and co-doped TiO2/C nanocomposites were derived from the pyrolysis of Ti-MOFs at 800 °C under different gaseous atmospheres and their photocatalytic performance were investigated. The gaseous atmosphere during pyrolysis plays a critical role in determining the structural, textural, optical and physicochemical properties of the derived TiO2/C composites due to the synergistic effect of nitrogen-containing species, carboxylate and sulfur functionalized porous carbon as well as N/S co-doped TiO2 nanoparticles. All the Ti-MOFs derived TiO2/C composites exclusively possess homogeneously distributed TiO2 nanoparticles in a functionalized disc-like porous carbon matrix and demonstrate much enhanced adsorption and photodegradation performance than commercial TiO2 under the same conditions. The adsorption of methylene blue (MB) in dark on these TiO2/C composites are dominated with pseudo second-order kinetic model and the high adsorption capacity of MB in dark on composite TiO2/C derived from MIL-125(Ti) in argon is due to its high surface area with predominant mesoporous carbon matrix in the composite. The composite N-O-TiO2/C derived from NH2-MIL-125(Ti) in water vapor exhibited the highest photodegradation activity with 99.7% MB removal in 3 hours under visible light due to the optimal anatase/rutile phasejunction, together with the formation of photoactive oxygen-rich N-O like interstitial/intraband states above the valence band of TiO2, as well as the presence of N-containing species and -OH/-COOH multi-functional groups with superhydrophilic nature of the composite. This simple one-step and easily modifiable approach can be further employed to modulate homogeneously dispersed multi-functionalized and co-doped metal oxide/carbon nanocomposites for various environment and energy-related applications.