https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:35936 in-situ precipitation of CeO₂ nanoparticles (size: ~26 nm) on the surface of flower-like Bi₂MoO₆ superstructures (diameter: 2.1-3.5 µm) by a simple method. The as-prepared photocatalysts were systematically characterized by a range of techniques. The photocatalytic degradation of rhodamine B (RhB) dye, methyl orange (MO) dye and tetracycline (TC) antibiotic by this novel photocatalyst was investigated under visible-light irradiation. The CeO₂/Bi₂MoO₆ heterojunction with a CeO₂/Bi₂MoO₆ weight ratio of 0.05 (0.05Ce-Bi) exhibited the highest photocatalytic activity with the RhB degradation efficiency of 100% in 75 min, which was considerably higher than those of pristine CeO₂ (26.8%) and Bi₂MoO₆ (80.3%) as well as their physical mixtures (74.8%). The more efficient separation of electron-hole pairs was identified as the primary reason of the enhanced photocatalytic activity. Moreover, the synthesized material maintained satisfactory activity even after 6 recycling runs, indicating its high photocatalytic stability. Therefore, our finding offers a new avenue for development of stable and efficient heterojunction photocatalysts for environmental purification.]]> Wed 01 Jul 2020 10:18:43 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 ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:35273 xO_yI_z/g-C₃N₄, namely, g-C₃N₄/BiOI, g-C₃N₄/Bi₄O₅I₂, and g-C₃N₄/Bi₅O₇I. g-C₃N₄/BiOI is prepared by a direct precipitation method, and g-C₃N₄/Bi₄O₅I₂ and g-C₃N₄/Bi₅O₇I are obtained by in situ calcination transformation of g-C₃N₄/BiOI at different temperature. Among them, g-C₃N₄/BiOI and g-C₃N₄/Bi₄O5I₂ are type-I heterojunction, and g-C₃N₄/Bi₅O₇I belongs to type-II heterojunction. The photocatalyitc activity is surveyed by decomposition of diverse industrial contaminants, including methyl orange, bisphenol A and tetracycline hydrochloride under visible light irradiation (λ > 420 nm). It is found that g-C₃N₄/Bi₅O₇I shows largely enhanced photodegradation performance compared to g-C₃N₄/BiOI and g-C₃N₄/Bi₄O5I₂. The much higher photocatalytic activity of g-C₃N₄/Bi₅O₇I is attributed to the enhanced specific surface area, more efficient charge separation and surface transfer efficiency and increased density of charge carriers owing to the formation of type-II heterojunction. The study provides a reference for in situ fabrication of hierarchical photocatalysts with diverse heterojunction types for optimizing photocatalytic activity.]]> Thu 17 Jun 2021 12:50:03 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:34102 in-situ anchoring Ag₃VO₄ nanoparticles (size: ~21 nm) on the surface of Bi₂WO₆ microflowers (diameter: 2.5-4.5 µm) by a facile deposition route. The photocatalytic activity of these heterojunctions were studied by decomposing cationic dye rhodamine B (RhB), anionic dye methyl orange (MO) and neutral para-chlorophenol (4-CP) under visible light irradiation (λ > 400 nm). Among all the tested catalysts, the heterojunction with a Ag₃VO₄/Bi₂WO₆ molar ratio of 0.15/1 displays the maximum activity with the RhB degradation rate constant of up to 0.0392 min^-1, a 6.7 or 1.7 times more enhancement compared with the pure Bi₂WO₆ or Ag₃VO₄. It is found that the introduction of Ag₃VO₄ is in favor of suppressing the electron-hole pair recombination of Bi₂WO₆, leading to an enhanced photocatalytic activity with good stability. The photogenerated holes (h⁺) and superoxide radicals (O·₂¯) play critical roles during the photocatalytic process. Ag₃VO₄/Bi₂WO₆ will have great potential in applications for environmental remediation due to the facile preparation method and superior photocatalytic activity.]]> Thu 07 Feb 2019 14:26:20 AEDT ]]>