https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:39073 2/g-C₃N₄ based photocatalysts remains a major hurdle to their successful application for the remediation of water-soluble contaminants such as herbicides and heavy metals. Herein, we develop new photocatalysts based on the graft of three different cyclodextrins (α-CD, β-CD and γ-CD) on MoS₂/g-C₃N₄ composites (CDs/MoS₂/g-C₃N₄) for the removal of glyphosate and Cr (VI) from simulated agricultural runoff. CDs/MoS₂/g-C₃N₄ show remarkably enhanced photocatalytic activities for glyphosate degradation and Cr (VI) reduction compared to pristine MoS₂/g-C₃N₄. In addition, γ-CD/MoS₂/g-C₃N₄ exhibits the highest hydrophilicity and photocatalytic activity among these three different cyclodextrins grafted MoS₂/g-C₃N₄. The mechanistic investigation indicates that cyclodextrins can not only increase the accumulation of glyphosate and Cr (VI) onto the surface of CDs/MoS₂/g-C₃N₄ but also facilitate the fleet separation of photo-induced electron-hole pairs. In summary, these results collectively imply that the graft of cyclodextrins could be an effective strategy to improve the photocatalytic efficiency of MoS₂/g-C₃N₄ composites for the removal of glyphosate and Cr (VI) from simulated agricultural runoff.]]> Wed 04 May 2022 15:10:42 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:47667 3N₄/TiO₂ nanocomposite was prepared as a photocatalyst (PC) active under visible light (λ≥420 nm) by preparation of graphitic carbon nitride (g-C₃N₄) from melamine followed by an efective easy impregnation method. Several g-C₃N₄/ TiO₂ composites containing 1 to 12 wt% g-C₃N₄ were synthesized and characterized using X-ray difraction (XRD) analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), diferential thermal analysis (DTA), photoluminescence (PL) spectroscopy, difusion refectance spectroscopy (DRS), and Brunauer–Emmett–Teller (BET) measurements. A photocatalytic mechanism is proposed based on the relative positions of the energy bands of the two constituents. Compared with its individual components, g-C₃N₄/TiO₂ demonstrated unusually high photocatalytic activity for phenol decomposition in aqueous phase under visible-light irradiation. The heterojunction was optimized in the 5 wt% g-C₃N₄/TiO₂ nanocomposite due to the well-matched bandgap structure (optimum loading) and excellent electron–hole pair separation in the conduction and valence band of TiO₂ and g-C₃N₄, respectively. After 2 h of visible-light irradiation, 68 % degradation was observed when using this optimum composition. The performance was slightly decreased (to 66 %) after recycling of the catalyst four times (used a total of five times), but remained reliable for industrial applications considering other factors. In this system, TiO₂ (Degussa P25) seems to play the principal PC role, while g-C₃N₄ acts as a sensitizer for absorption of visible light. Due to the enhanced visible-light absorption ability enabled by g-C₃N₄ in the composite, stable electron–hole (e⁻–h⁺) pairs produced at the interface of the heterojunction lead to generation of highly reactive free radicals (·O₂, ·OH, etc.) which together initiate degradation of phenol but individually sufer from some limitation that must be overcome. The thermal stability and recycling efciency of this PC will enable its use in industrial applications as a cost-efective sustainable cleanup candidate.]]> Tue 24 Jan 2023 15:47:58 AEDT ]]>