Low-temperature route to metal titanate perovskite nanoparticles for photocatalytic applications

Abstract

MTiO3 (M=Ca, Sr, Ba) nanoparticles were synthesized by a one-step room-temperature ultrasound synthesis in ionic liquid. The obtained samples are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, UV–vis diffuse reflectance, Raman and IR spectroscopy and their capability in photocatalytic hydrogen evolution and methylene blue degradation was tested. Powder X-ray diffraction and Raman spectroscopic investigations revealed the products to crystallize in the cubic perovskite structure. SEM observations showed that the obtained CaTiO3 consists of nanospheres, BaTiO3 of raspberry-like shaped particles of 20nm in diameter. SrTiO3 particles have cubic-like morphology with an edge length varying from 100 to 300nm. SrTiO3 exhibited the highest catalytic activity for photocatalytic H2 evolution using only 0.025wt.% Rh as co-catalyst and for the degradation of methylene blue under UV irradiation. The influence of parameters such as synthesis method, calcination temperature, and doping with nitrogen on the morphology, crystallinity, chemical composition, and photocatalytic acivity of SrTiO3 was studied. Heating the as-prepared SrTiO3 to 700°C for extended time leads to a decrease in surface area and catalytic activity. Ionothermal prepared SrTiO3 exhibits a higher activity than sonochemically prepared one without co-catalyst due to a synergistic effect of anatase which is present in small amount as a by-phase. After photodeposition of Rh, however, the activity is lower than that of the sonochemically prepared SrTiO3. Nitrogen-doped SrTiO3 showed photocatalytic acivity under visible light irradiation.