Sonochemical assisted hydrothermal synthesis of pseudo-flower shaped Bismuth vanadate (BiVO₄) and their solar-driven water splitting application

Bismuth vanadate (BiVO₄) is a well-known photocatalyst due to its lower bandgap (E_g) and visible electromagnetic light absorption capacity. Herein, we reported the pulse ultra-sonochemical assisted hydrothermal approach to synthesize S-BiVO₄. For the comparison purpose, H-BiVO₄ is also synthesized via conventional hydrothermal approach. The surface morphology of S-BiVO₄ through scanning electron microscope (SEM) indicates condensed microarrays (MAs) having pseudo-flower shapes. The energy dispersive X-rays (EDX) spectrum also confirmed the elemental percent composition of Bi, V and O in BiVO₄. X-rays diffraction (XRD) pattern further confirmed the monoclinic scheelite phase of S-BiVO₄. Fourier transformed infrared (FTIR) spectrum showed Bi–O and Bi–V–O vibrational bands at 1382 and 1630 cm⁻¹, respectively. The diffuse reflectance spectroscopy (DRS) indicated absorption edge at ∼515 nm, corresponds to bandgap value (E_g) of 2.41 eV, which is suitable range for water splitting applications. The photocurrent density from water splitting under artificial 1 SUN visible light source found at 60 and 50 μA/cm² for S-BiVO₄ and H-BiVO₄, respectively. The stability test through chronoamperometry showed that S-BiVO₄ was more stable than H-BiVO₄. It can be depicted from the growth mechanism that ultrasonication played a definite role in the overall synthesis of pseudo-flower shaped S-BiVO₄ MAs.