Cu-doped K0.5Na0.5NbO3 films obtained by the sol-gel method and their application in the photodegradation of methylene blue

The remnant polarization of ferroelectric films is a property that can be manipulated by the application of external electric fields and used in the photodegradation of organic pollutants. In this study, the synthesis of copper (Cu) doped K0.5Na0.5NbO3 (KNN) thin films obtained by the sol-gel method and grown on glass-ITO substrates by spin coating is presented, to evaluate the efficiency in the photocatalytic degradation of methylene blue (MB). Films with different Cu concentrations (0.25%, 0.5%, 1%) are synthesized and their structural, morphological, ferroelectric, and photocatalytic properties are studied. For this, characterizations are carried out by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), piezoelectric force microscopy, and photocatalytic performance with the help of UV-Vis spectroscopy measurements. The results show that Cu doping shows the largest crystallite size at 0.25% of Cu. The sample with 1% Cu showed the best performance in the photodegradation of methylene blue, up to 35% with negative polarization. These results suggest that thin films of Cu-doped KNN, obtained by the sol-gel method, offer an alternative for the degradation of organic pollutants in environmental applications by taking advantage of their ferroelectric properties.