Photocatalytic activity of CaTiO3 synthesized by solid state, sol–gel and hydrothermal methods

The structures and compositions of CaTiO3 samples synthesized by solid state, sol–gel, and hydrothermal methods were characterized by various means such as X-ray diffractometer, scanning electron microscope, Brunauer–Emmett–Teller, Fourier transform infrared spectrometer, Raman spectra, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection spectra. Photocatalytic activity of CaTiO3 was investigated via measuring the photodegradation of methylene blue. As-prepared samples by three methods were orthorhombic CaTiO3, showing heterogeneous sizes and diverse morphologies. Functional groups including Ti–O, N–O, and OH were detected for three CaTiO3 samples. In particular, the XPS spectra suggested the presence of Ti–O–N or Ti–N–O structure in CaTiO3 lattice, indicating that N in air or Ca(NO3)2·4H2O (Ca source) may lead to forming N-doped CaTiO3 by solid state method or sol–gel and hydrothermal methods. Photocatalytic activity of CaTiO3 prepared by the hydrothermal method was the highest among three CaTiO3 samples, whereas it was lower than that of TiO2.