Ternary nanocomposite of NH2-MIL-125(Ti) MOF-modified TiO2 nanotube arrays (TNTs) with GO electron mediator for enhanced photocatalytic conversion of CO2 to solar fuels under visible light

Abstract

Facile fabrication of highly efficient NH2-MIL-125(Ti)-GO-TNTs ternary nanocomposite was achieved through a simple drying-deposition approach. The newly developed photocatalyst exhibited efficient performance in CO2 photoreduction owing to hierarchically structured TiO2 nanotubes with porous MOF nanoparticles and GO nanosheets, which acted as the electron mediator. The experimental investigations revealed the superiority of the MOF-modified TNTs over pure TNTs, indicating the significant role of MOF in improving the optoelectronic properties and thus increasing the photocatalytic activity. The highest photocatalytic performance for CO2 reduction was obtained using ternary nanocomposite with CO production of 29782 μmol m−2. However, when compared to pure TNTs, CH4 production was reduced, indicating that the NH2-MIL-125(Ti) MOF preferentially produces CO rather than CH4. The effect of pressure displayed a direct relationship with the photocatalytic production of both products. Furthermore, the nanocomposite's recyclability and stability studies revealed continuous CO and CH4 production in multiple cyclic runs with no significant photocatalyst deactivation. This study gives new ideas for making and developing cheap Ti metal and other low-cost, effective materials that can be used to recycle CO2 gas emissions into useful solar fuels.