Surfactants Modulating of BiVO₄ on Photocatalytic Property as a Regulation of Surface Free Energy

BiVO₄ is a stable photocatalytic material but has poor photocatalytic activity in visible light. Herein, the surfactants were investigated to enhance the photocatalytic degradation of tetracycline (TC) of BiVO₄ through a hydrothermal method. The different molecular structures and properties of surfactant-modified BiVO₄ show clustered small spheres and stacked plate-like microcrystals. The <i>N</i>-hexadecyltrimethylammonium chloride (CTAC)-modified BiVO₄ (BiVO₄-CTAC) with stacked plate-like morphology increases the light absorption range and decreases the energy band gap. Surfactants with different hydrophilic groups and molecular structures affect the formation process of BiVO₄, regulating the morphology, crystal structure, and crystalline surface exposure of BiVO₄. BiVO₄-CTAC has demonstrated superior TC degradation efficiency compared with the original BiVO₄ (BiVO₄-Blank). This enhancement is attributed to the observation in the Nyquist plot, where BiVO₄-CTAC exhibits the smallest arc radius, indicative of reduced charge transfer resistance and improved charge separation. Furthermore, holes (h⁺) and superoxide radicals (^•O₂^-) reactive species are the main active radicals for TC photocatalytic degradation. This study develops a novel method to synthesize monoclinic phase lamellar BiVO₄ materials by simply changing the surfactant type. This study holds potential implications for advancing surfactant-assisted synthesis of high-efficiency photocatalysts.