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

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.