Effect of pH Variation on Structural, Optical and Shape Morphology of BiVO 4 Photocatalysts

Visible light driven photocatalysts have gathered enormous interest in recent years because of their capability to harvest energy directly from sunlight by water splitting and also to purify water. Bismuth Vanadate (BVO) is one of the most potential photocatalysts for water pollutant degradation and hydrogen production by oxidation of water. In our study, highly crystalline Bismuth Vanadate nanoparticles have been synthesized by a straightforward hydrothermal route where pH is varied to observe the change in morphology of the particles. Thermal analysis confirmed the tetragonal to monoclinic phase transformation temperature at 350 °C. A hierarchical development of monoclinic - tetragonal heterostructure of Bismuth Vanadate is further confirmed by Rietveld refinement of XRD patterns and the obtained particle size is 27nm. Band gap energy has been tailored through control of pH to explore the optical band gap for suitable photocatalytic properties. It is found that a heterostructure composed of rod and spherical shaped nanoparticles for a pH value 6.5, closer to neutral, demonstrating better optical properties for efficient photocatalytic activity with a band gap energy of 1.8 eV.