Magnetically Recoverable BiVO4/Fe3O4/g-C3N4 Heterojunction Photocatalyst for Visible-Light Degradation of Methylene Blue
Anggi Anggraeni (a), Tien Setyaningtyas (a), Kapti Riyani (a), and Anung Riapanitra (a),

a) Department of Chemistry, Faculty of Mathematics and Natural Science, Jenderal Soedirman University, Purwokerto, 53122, Central Java, Indonesia.

Abstract

The development of efficient and magnetically separable photocatalysts is essential for wastewater treatment applications. In this study, a ternary heterojunction composite, BiVO4/Fe3O4/g-C3N4 (BNFC), was successfully synthesized via a hydrothermal method with varying g-C3N4 mass fractions. The materials were characterized using SEM-EDX and UV-Vis DRS. Morphological analysis revealed plate-like BiVO4, flake-like Fe3O4, and layered g-C3N4 nanosheets, while the composite structure demonstrated good interfacial integration among the three phases. Optical analysis showed that BNFC-0.5 exhibited a redshift in the absorption edge and a reduced band gap (2.48 eV) compared to pristine BiVO4 (2.51 eV), indicating enhanced visible-light utilization due to interfacial electronic interactions. Photocatalytic activity was evaluated through the degradation of methylene blue (MB) under visible-light irradiation. Among the prepared samples, BNFC-0.5 achieved the highest degradation efficiency of 90.56% within 180 minutes, outperforming pure BiVO4, Fe3O4, g-C3N4, and other composite variations. The improved performance is attributed to the synergistic heterojunction effect, which promotes effective charge separation and suppresses electron-hole recombination. This work demonstrates that a low g-C3N4 loading is sufficient to significantly enhance visible-light photocatalytic performance while enabling magnetic recovery, offering a cost-effective ternary photocatalyst design.

Keywords: Photodegradation, Hydrothermal, Heterojunction, Methylene Blue, Visible-light photocatalysis.

Topic: Inorganics Chemistry