Abstract
In this study, molybdenum disulfide (MoS2) decorated on graphitic carbon nitride (g-C3N4) heterostructure catalysts at various weight ratios (0.5%, 1%, 3%, 10%, w/w) were successfully prepared via a two-step hydrothermal synthesis preparation method. The properties of the synthesized materials were studied by X-ray diffraction (XRD), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FT-IR), UV–Vis diffuse reflection spectroscopy (DRS), scanning electron microscopy (SEM) and N2 porosimetry. MoS2 was successfully loaded on the g-C3N4 forming heterojunction composite materials. N2 porosimetry results showed mesoporous materials, with surface areas up to 93.7 m2g−1, while determined band gaps ranging between 1.31 and 2.66 eV showed absorption over a wide band of solar light. The photocatalytic performance was evaluated towards phenol oxidation and of Cr(VI) reduction in single and binary systems under simulated sunlight irradiation. The optimum mass loading ratio of MoS2 in g-C3N4 was 1%, showing higher photocatalytic activity under simulated solar light in comparison with bare g-C3N4 and MoS2 for both oxidation and reduction processes. Based on scavenging experiments a type-II photocatalytic mechanism is proposed. Finally, the catalysts presented satisfactory stability (7.8% loss) within three catalytic cycles. Such composite materials can receive further applications as well as energy conversion.
Highlights
There has been an increased interest in the development of more efficient and environmentally friendly methods for the removal of pollutants from wastewater, and for this reason the advanced oxidation processes (AOPs) are widely used. Their effectiveness for organics removal is based on the production of hydroxyl radicals, which are powerful oxidizing agents
Mesoporous MoS2 /g-C3 N4 heterostructures were successfully synthesized via a two-step hydrothermal synthesis at various weight ratios
A considerable enhancement of the photocatalytic efficiency was observed for the binary system compared to the single component systems, indicating a promoting synergistic effect
Summary
Toxic metal ions such as Cr(VI) may be present in combined wastewater streams; treatment methods should be capable of removing both organic and inorganic pollutants. Conventional treatment methods present either low removal of certain organic pollutants or are incapable of simultaneous removal of organics and toxic metal ions [2]. There has been an increased interest in the development of more efficient and environmentally friendly methods for the removal of pollutants from wastewater, and for this reason the advanced oxidation processes (AOPs) are widely used. Their effectiveness for organics removal is based on the production of hydroxyl radicals, which are powerful oxidizing agents. Heterogeneous photocatalysis, which presents advantages over other removal techniques as it can be applied for both oxidation and reduction of pollutants in ambient conditions in the presence of solar radiation and for organic pollutants, can lead to complete mineralization [2,3,4,5,6]
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