| Summary: | To bridge the technical gap of heterojunction induction control in conventional semiconductor photocatalysts, a method of regulating the growth of heterojunctions utilizing biomimetic structures was designed to prepare a series of Bi<sub>2</sub>WO<sub>6</sub>/Bi<sub>2</sub>O<sub>3</sub> vertical heterojunction nanocomposites for the disposal of environmentally hazardous tetracycline wastewater difficult to degrade by conventional microbial techniques. Porous Bi<sub>2</sub>O<sub>3</sub> precursors with high-energy crystalline (110) dominant growth were produced using the sunflower straw bio-template technique (SSBT). Bi<sub>2</sub>WO<sub>6</sub> with a (131) plane grew preferentially into 2.8 to 4 nm pieces on the (110) plane of Bi<sub>2</sub>O<sub>3</sub>, causing a significant density reduction between Bi<sub>2</sub>WO<sub>6</sub> pieces and a dimensional decrease in the agglomerated Bi<sub>2</sub>WO<sub>6</sub> spheres from 3 μm to 700 nm since Bi<sub>2</sub>WO<sub>6</sub> grew on the structure of the biomimetic Bi<sub>2</sub>O<sub>3</sub>. The optimal 1:8 Bi<sub>2</sub>WO<sub>6</sub>/Bi<sub>2</sub>O<sub>3</sub> coupling catalyst was obtained via adapting the ratio of the two semiconductors, and the coupling ratio of 1:8 minimized the adverse effects of the overgrowth of Bi<sub>2</sub>WO<sub>6</sub> on degradation performance by securing the quantity of vertical heterojunctions. The material degradation reaction energy barrier and bandgap were significantly reduced by the presence of a large number of vertical heterojunction structures, resulting in a material with lower impedance and higher electron–hole separation efficiency; thus, the degradation efficiency of 1:8 Bi<sub>2</sub>WO<sub>6</sub>/Bi<sub>2</sub>O<sub>3</sub> for tetracycline hydrochloride reached 99% within 60 min. In conclusion, this study not only successfully synthesized a novel photocatalyst with potential applications in water pollution remediation but also introduced a pioneering approach for semiconductor-driven synthesis.
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