Browsing by Author "Prekodravac, J."

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    Black titania: Turning the surface chemistry toward visible-light absorption, (photo) remediation of hazardous organics and H2 production
    (Elsevier, 2022) Prekodravac, J.; Giannakoudakis, D.A.; Colmenares, J.C.; Nair, N.; Vasiljević, B.; Kepić, D.
    Environmental protection and energy conversion by state-of-the-art photocatalysts emerge as imperative in pursuit for ideal, sustainable, and green oriented solutions. However, major drawbacks in broader application of one of the most promising semiconductor photocatalyst, titanium dioxide (TiO2), lie in the need for enhancing visible-light absorption and elevating the photocatalytic reactivity. Toward these directions, narrowing the material band gap and functionalization of the surface chemistry are among the most prosperous materials design approaches. As reported in earlier work, the surface structure engineering proved to be an encouraging approach to endow optical and electrical properties of the TiO2-based material. For the first time, the black powder of TiO2 with a disordered lattice and hydrogen surface doping was obtained through hydrogenation under high pressure and temperature, consequently leading to narrowing the optical band gap to 1.54eV. The presented chapter aims to reveal in-depth all the literature available information related to the black titania synthesis in addition of sharing in details its prosperous physicochemical properties. Feature information related to the photocatalytic activity of black TiO2 as well as of the most crucial features will also be provided. Finally, the chapter will conclude with the derived significant benefits of such material properties in photocatalytic treatment of organic pollutants and hydrogen production. © 2023 Elsevier Inc. All rights reserved.
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    Homogeneous photocatalysts immobilized on polymeric supports: Environmental and chemical synthesis applications
    (Elsevier, 2021) Prekodravac, J.; Nair, V.; Giannakoudakis, D.A.; Hsu, S.H.-Y.; Colmenares, J.C.
    The interest in homogeneous photocatalysis arises from the high activity and selectivity advantages of controlled photochemical transformations such as synthesis of chemical/pharmaceutical products or complete degradation/mineralization of hazardous compounds. However, the major drawback of homogeneous photocatalytic reactions lies in the separation and recovery of the photocatalyst after the reaction, necessary to make the photocatalytic process eco-friendly. Immobilization of homogeneous photocatalysts on different supports is considered to be a viable method to increase the retainability and reusability of the photocatalyst simultaneously. This chapter aims to provide an in-depth information related to the immobilization of various homogeneous photocatalysts on well-known synthetic and natural polymers. Detailed information related to the potential environmental and chemical synthesis applications of immobilized homogeneous photocatalysts are also discussed. Finally, this chapter concludes with a new direction in emerging technologies for developing better supported photocatalysts. © 2021 Elsevier Inc. All rights reserved.
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    Ultrasound-assisted decoration of CuOx nanoclusters on TiO2 nanoparticles for additives free photocatalytic hydrogen production and biomass valorization by selective oxidation
    (Elsevier B.V., 2021) Giannakoudakis, D.A.; Qayyum, A.; Nair, V.; Khan, A.; Pradhan, S.R.; Prekodravac, J.; Rekos, K.; LaGrow, A.P.; Bondarchuk, O.; ?omot, D.; Triantafyllidis, K.S.; Colmenares, J.C.
    The herein presented ultrasound-assisted ultra-wet (US-UWet) impregnation synthetic approach was followed in order to avoid the drawbacks of the conventional wet impregnation synthesis. The goal was to homogeneously decorate the surface of the TiO2 nanoparticles with nanometric sized (< 4 nm) clusters of mixed cupric and cuprous oxides. The physicochemical features of the nanocomposite (TiO2[sbnd]CuOx) were determined by high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and Diffuse reflectance (DR) spectroscopy. TiO2[sbnd]CuOx showed an enhanced and continuous capability to generate molecular hydrogen upon low power ultraviolet irradiation. The benchmark commercial TiO2 P25 did not reveal any H2 formation under these conditions. TiO2[sbnd]CuOx presented also a high efficiency for the additives-free selective partial oxidation of two well established biomass derived model platform chemicals/building blocks, 5-hydroxymethylfurfural (HMF) and benzyl alcohol (BnOH) to the value-added chemicals 2,5-diformylfuran (DFF) and benzyl aldehyde (PhCHO), respectively. The nanocomposite showed higher DFF and PhCHO yield compared to P25. © 2021