4-chlorophenol CH3</NH3</PbI3 CuxO-ZnO catalyst DFT calculations Fe/N-TiO2 TiO2 TiO2 nanoparticles UV ageing ZnO advanced oxidation processes alkylalkoxysilane anodizing artificial rain band gap modification bio-based substances broadband spectra caffeine charge dynamics composite materials confocal microscope crystallinity degradation density functional theory (DFT) durability electron transport material hybrid nanomaterials hydrothermal hydrothermal synthesis low power white-light LED irradiation magnetic materials