Piezo-photocatalytic activity of Bi2VO5.5 for methylene blue dye degradation

Abstract

This study comprises the combined effect of piezocatalytic and photocatalytic activity to obtain improved piezo-photocatalytic dye degradation efficiency in visible light. Single-phase Bi2VO5.5 powder was prepared through solid-state synthesis at 750 °C in 8 h. Time-dependent photocurrent responses were conducted to understand the phenomenon of charge carrier transport in visible light. Bi2VO5.5 powder sample demonstrated high photocatalytic efficiency and good reusability possessing a bandgap value of 2.13 eV. Bi2VO5.5 powder sample attained ∼70% and ∼58% degradation efficiency during photocatalysis and piezocatalysis respectively. The piezo-photocatalytic methylene blue dye attained ∼82% degradation efficiency in 240 min duration of visible light illumination. The scavenger test depicted holes (h+) as the principal active species in the piezo-photocatalytic dye degradation. There incurred no severe loss in photocatalytic efficiency even after 4 cycles which proclaims the reusability of the Bi2VO5.5 powder sample. A study on the kinetic rate constant with varying dye concentrations was conducted. With varied dye concentration of 5, 10, 15 mg/L, the kinetic rate constant obtained was 0.00528, 0.0030, and 0.00125 min−1, respectively. Germination index was found through a phytotoxicity test using vigna radiata seeds. Here visible light along with mechanical energy has been used to achieve higher MB dye degradation efficiency through piezo-photocatalysis.