In-situ hydrothermal synthesis of Bi2S3 nanoribbons to construct Bi2S3/ BiVO4/TiO2 composite films with 96.1 % Cr(VI) reduction

With the rapid industrialization deteriorating heavy metal water pollution, photocatalytic technology has emerged as a promising solution. In this study, a novel in-situ hydrothermal technique enabled the integration of Bi2S3 nanoribbons and BiVO4 particles with TiO2 forming a stable Bi2S3/BiVO4/TiO2 composite film, and utilized sulfur (S) source concentration to regulate Bi2S3 morphology to enhance photocatalytic property of TiO2. The results show that with the introduction of S source, the morphology of Bi2S3 showed obvious evolution law. Under the low concentration of S source (1 mmol), Bi2S3 formed nanospines, evolving into nanoribbons (3,5 mmol) and nanosheets (7 mmol), with agglomeration observed at 10 mmol. When the amount of S source was 5 mmol (SVT-5), Bi2S3 nanoribbons was the most suitable morphology, and exhibited enhanced visible-light absorption and the narrowest bandgap (2.76 eV). SVT-5 demonstrated superior photoelectrochemical property: highest photocurrent density, lowest impedance, maximum carrier concentration, and prolonged carrier lifetime (15.2 ms). Under simulated solar light, SVT-5 achieved a reduction efficiency of 96.1 % and a reduction rate of 0.0336 min-1 for 5 mg/L Cr(VI) after 100 min, outperforming TiO2 and BiVO4/TiO2. Additionally, SVT-5 maintained 90 % efficiency after four cycles, highlighting its stability. This work provides a morphology-regulation strategy to enhance TiO2-based photocatalysts, offering a viable approach for heavy metal wastewater treatment and advancing applications in optoelectronics and environmental remediation.