Enhanced visible-light photocatalytic activity of Fe3O4@MoS2@Au nanocomposites for methylene blue degradation through Plasmon-Induced charge transfer

In this study, we synthesized Fe3O4@MoS2@Au nanoparticles as a photocatalyst for the degradation of methylene blue (MB). The presence of gold nanoparticles induced Localized Surface Plasmon Resonance (LSPR), extending the absorption range into the visible light spectrum. Under green light exposure (540 nm, 8 W), the Fe3O4@MoS2@Au photocatalyst exhibited remarkable performance, achieving a degradation efficiency of 98.95 %, outperforming Fe3O4@MoS2, which reached 72.46 %. The pseudo-first-order reaction rate constant for Fe3O4@MoS2@Au was 3.8 × 10−3 min−1, surpassing Fe3O4@MoS2 by 2.7 times. Additionally, Fe3O4@MoS2@Au demonstrated superior degradation efficiency under natural light, reaching 78 % after 3 h compared to 70.2 % for Fe3O4@MoS2. To elucidate the degradation mechanism, density functional theory (DFT) based computational simulations were employed to analyze the electron charge density at each step of the degradation process. The density of state simulation revealed a shift in electron energy levels towards higher energies in Fe3O4@MoS2@Au compared to Fe3O4@MoS2, thereby promoting electron transfer and enhancing the efficiency of photodegradation.