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

Abstract

Multi-functionalized and co-doped TiO2/C nanocomposites derived from the pyrolysis of TiMOFs at 800 oC under different gaseous atmospheres were produced 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 effects of nitrogen-containing species, carboxylate and/or sulfur functionalized porous carbons and N/S co-doped TiO2 nanoparticles. All the TiMOFs derived TiO2/C composites exclusively possess homogeneously distributed TiO2 nanoparticles in functionalized disc-like porous carbon matrix and demonstrate much enhanced adsorption and photodegradation performance than commercial TiO2 under the same conditions. The adsorption and degradation of methylene blue (MB) in dark on these TiO2/C composites are dominated with pseudo second-order kinetic model and the high adsorption and degradation 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 oxygenrich N-O like interstitial/intraband states above the valence band of TiO2, as well as the presence of rich 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 many homogeneously dispersed multi-functionalized and co-doped metal oxide/carbon nanocomposites for various environment and energy-related applications.