Semiconductor-based photocatalyst materials played an important role in the degradation of organic compounds in recent years. Photocatalysis is a simple, cost-effective, and environmentally friendly process for degrading organic compounds. In this work, vanadium pentoxide (V₂O₅) and V₂O₅/RGO (reduced graphene oxide) composite were synthesized by a hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, and UV-Vis spectroscopic analysis, etc. Raman analysis shows the occurrence of RGO characteristic peaks in the composite and different vibrational modes of V₂O₅. The band gap of flake-shaped V₂O₅ is reduced and its light absorption capacity is enhanced by making its composite with RGO. The photocatalytic degradation of methylene blue (MB) was studied using both V₂O₅ and V₂O₅/RGO composite photocatalyst materials. The V₂O₅/RGO composite exhibits a superior photocatalytic performance to V₂O₅. Both catalyst and light play an important role in the degradation process.

In this research work, we reported the synthesis of a spherical-shaped bismuth vanadate (BiVO₄) photocatalyst using a cost-effective, simple, chemical hydrothermal method and studied the effect of deposition temperatures on the structural, morphological, optical properties, etc. The XRD result confirmed the monoclinic scheelite phase of BiVO₄. An XPS study confirmed the occurrence of Bi, V, and O elements and also found that Bi and V exist in +3 and +5 oxidation states, respectively. SEM micrographs revealed the spherical-shaped morphology of the BiVO₄ photocatalyst. Optical investigation showed that the bandgap of the BiVO₄ photocatalyst varied between 2.25 and 2.32 eV. The as-synthesized BiVO₄ photocatalyst was used to study the photocatalytic degradation of crystal violet (CV) dye under visible light illumination. The photocatalytic degradation experiment showed that the degradation percentage of crystal violet dye using BiVO₄ reached 98.21% after 120 min. Mineralization of crystal violet dye was studied using a chemical oxygen demand analysis.

In recent year, sonochemistry has fascinated some interest in the fabrication of nanostructured materials and functional nanoparticles because the chemical activity of ultrasound may cause different effects such as the generation of heat, mass transfer or intimate contact between materials, distribution of contaminated layers of chemicals and generation of free chemical radicals. In this work, Cu2ZnSnS4 (CZTS) photocatalyst is prepared by simple, cost effective, sonochemical method and used for photocatalytic degradation of phthalic acid. The ultrasonic treatment affects the structural, morphological, optical, contact angle properties of CZTS photocatalyst. The XRD and FT-Raman spectroscopy study shows the formation of a single phase CZTS with kesterite structure. SEM analysis reveals nano-spherical architecture with pinhole and crake free surface. The optical study shows that band gap energy lies in the visible region of the solar spectrum and useful for visible light assisted photocatalysis. The end results show that the CZTS photocatalyst exhibited about 56% degradation of phthalic acid under sunlight illumination. The mineralization study of phthalic acid is done by determining chemical oxygen demand (COD) values.