Highly Efficient Visible-Light-Induced Photocatalytic Production of Hydrogen for Magnetically Retrievable Fe₃O₄@SiO₂@MoS₂/g-C₃N₄ Hierarchical Microspheres

A new multifunctional compound containing hierarchical microspheres of Fe₃O₄@SiO₂@MoS₂/g-C₃N₄ (FSMG) was created. The microspheres comprised Fe₃O₄@SiO₂ as a magnetic component and a heterostructure of MoS₂/g-C₃N₄ as an outer shell, and both elements are compounded by an effective and applicable method and can be used in photocatalytic applications. Highly efficient separation of the photodriven pairs of electron/hole pairs (e^-/h⁺) was exhibited with the as-synthesized FSMG structures under visible light. The photocatalytic activities of Fe₃O₄@SiO₂@MoS₂, g-C₃N₄, and FSMG are assessed by surveying the hydrogen (H₂) production and rhodamine B (RhB) photodegradation from water. These contrasting studies show that microspheres of FSMG show promising visible-light-induced photocatalytic activity and exhibit 1.99-fold and 3.38-fold increased activity over that of Fe₃O₄@SiO₂@MoS₂ and g-C₃N₄ mechanisms, respectively, in RhB degradation and a 4.13-fold and 11.09-fold increase in H₂ production from water, respectively. Furthermore, the FSMG microspheres also show good recovery with a magnet. As studied by XPS, TEM, and SEM; photocurrent curves, trapping agent experiments; and Nyquist impedance spectroscopy, the extended light response range, intimate contact interface, improved separation speed of carriers, and higher photocurrent density resulted in the increased photocatalytic activity of heterostructures of MoS₂/g-C₃N₄. MoS₂ trapped electrons to improve the lifespan of classified electron/hole pairs, while the assembled holes located at the surface of g-C₃N₄ continuously oxidized the dye, which provided a controllable path for photodegradation and H₂ production. The improved systems and principles stated here will be of great significance in heterogeneous photocatalysis.