Hierarchical porous TiO with a uniform distribution of anchored gold nanoparticles for enhanced photocatalytic efficiency and accelerated charge separation for the degradation of antibiotics.

A novel approach to synthesize porous Au/TiO nanocomposites has been achieved through a pyrolytic strategy by employing NH-MIL-125(Ti) as a TiO precursor, and photo-deposition of Au nanoparticles (NPs) onto porous nanocrystalline TiO with varying Au contents (0.05-0.5%). TEM images of Au/TiO nanocomposites showed that TiO particles were spherical structures, highly dispersed, and homogeneous with diameters of 10-15 nm, and Au NPs (20-30 nm) were anchored onto porous TiO matrices with a uniform distribution. The synthesized Au/TiO nanocomposites were assessed through the degradation of two antibiotic models, metronidazole (MNZ), and trimethoprim (TMP), under visible light and compared with undoped TiO and commercial TiO (P-25). The synthesized Au/TiO photocatalyst revealed enhanced photocatalytic performance in the mineralization (80%) and degradation (100%) of MNZ and TMP in both water matrices compared to undoped TiO (60%, 76%) and commercial P-25 (48%, 65%). The obtained 0.1% Au/TiO nanocomposite could complete the mineralization of TMP and MNZ with rate constant values (4.47 × 10 min and 5.23 × 10 min) owing to the large well-developed porosity and high surface area of TiO and the small size of Au NPs with high dispersity, surface plasmon resonance, and stability. The recyclability of the 0.1% Au/TiO nanocomposite exhibited high durability without the leaching or loss of photocatalytic performance after four cycles. Complete degradation was achieved within 100 min in the water matrix from real wastewater, indicating promising results for the degradation of pharmaceuticals in the different water matrices. The present work opens a new route to synthesize low-cost, effective, and high photocatalytic performance nanocomposites with a small Au content as a cocatalyst onto semiconductor materials.