Facile Synthesis of Gram-Scale Mesoporous Ag/TiO Photocatalysts for Pharmaceutical Water Pollutant Removal and Green Hydrogen Generation.

This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO. Alongside paracetamol degradation, Ag/TiO led to the generation of 1729 μmol H g h. This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)- and nonmetal (nitrogen)-doped TiO, which also showed a positive response. Using a combination of calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO was due to the surface Fermi-level change of TiO and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.