Effect of substituting molybdenum atoms with tungsten on photocatalyst activity of cesium salt of keggin type polyoxometalates decorated magnetic ceria

Herein the potential use of cesium salts of polyoxometalate incorporated ceria and magnetic ceria as a photocatalyst for the photodegradation of Congo red was studied. Polyoxometalates salts (cesium salts of tungestophosphoric acid (H3PW12O40), molybdophosphoric acid (H3PMo12O40), and 6-molybdo tungestophosphoric acid (H3PW6Mo6O40)), having Keggin structure with large cations like Cs+, are porous materials. The morphological and structural studies of synthesized nanocomposites were carried out using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Results indicated that the Fe3O4@CeO2/Cs-PMoyW12-yO40 and CeO2/Cs-PMoyW12-yO40 (y = 0, 6, 12) nanocomposites are successfully synthesized. UV–vis diffuse reflectance spectroscopy determined the absorption edge and band gap energies of the prepared nanocomposites as a direct semiconductor. All the obtained structures were applied as photocatalys for degradation of Congo red dye in aqueous solutions under visible light. The Fe3O4@CeO2/Cs-PMo6W6O40 photocatalyst exhibited the highest photocatalytic activity under visible light.