From AgI/TiO2 to Ag/TiO2: effects of the annealing temperature on the compositions, porous nanostructures, and visible-light photocatalytic properties

AgI/TiO2 and Ag/TiO2 porous nanostructures were synthesized using AgNO3, KI, thioglycollic acid, and tetrabutyl orthotitanate as a precursor. AgI nanoparticles were used as seeds to initiate the nucleation of a precursor TiO2 shell, and thioglycollic acid acted as a hydrolysis inhibitor and porosity promoter. The hybridized samples were annealed at different temperatures. Porous AgI/TiO2 nanostructures were formed at low annealing temperatures (300 and 400 °C). At 600 °C, the porous Ag/TiO2 nanostructures exhibited a plasmon resonance effect. The formation mechanism of the different porous nanostructures was also investigated. Methylene blue solutions were used as wastewater to evaluate the visible-light photocatalytic activity of the samples. The porous nanostructured photocatalyst exhibited substantially high visible-light-induced photocatalytic activity for the photodegradation of methylene blue compared with pristine AgI and TiO2 nanoparticles.