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7. Design of a highly photocatalytically active ZnO/CuWO4 nanocompositeMatjaz Valant, Saim Emin, 2017, published scientific conference contribution abstract (invited lecture) Abstract: We report the synthesis, photocatalytic activity and mechanistic study of a novel heterostructure (HTS) with an efficient charge separation. A ZnO/CuWO4 HTS material is reported for the first time. The nanocomposite (NC) consists of CuWO4 nanoparticles (ca. 200-400 nm) decorated with ZnO nanorods (ca. 30 nm, 100 nm length) and is shown to be a highly active photocatalyst for decomposition of model contaminants including methyl orange and terephthalic acid. The ZnO/CuWO4 interface is shown to be the key for controlling the enhanced activity of the composite material. Transient absorption spectroscopy studies demonstrated that a photoinduced charge transfer across the ZnO/CuWO4 interface increased electron-hole lifetime by 3 orders of magnitude, from < 20 s in ZnO to 30 ms in the ZnO/CuWO4 NC sample. Our findings show that through interface design efficient HTS materials can be prepared for a wide range of photocatalytic applications.
Found in: osebi
Keywords: CuWO4, nanocomposite, transient absorption spectroscopy
Published: 28.08.2017; Views: 4262; Downloads: 0
 Fulltext (621,87 KB) |
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9. Tungsten carbide thin films for electrochemical water splitting studiesHasan Okuyucu, Matjaz Valant, Ali Semerci, Cesur Altinkaya, Saim Emin, Abdullah Yildiz, 2017, published scientific conference contribution abstract Abstract: We used wet-chemistry techniques to prepare colloidal tungsten (W) nanoparticles (NPs). The synthesis of W NPs was conducted using the so called hot-matrix method in 1-octadecene [1]. The sizes of obtained W NPs are in the order of 2 - 5 nm. These W NPs are coated with hydrophobic molecules which allow their dispersion in organic solvents like choloroform (CHCl3). It was found that the colloidal stability of the dispersions is exceptionally high exceeding several years. The stability of W NPs which prevents coagulation allows the preparation of thin films with uniform thicknesses by spin-coating, inkjet-printing and spray coating.
We have prepared tungsten carbide (W2C, WC) thin films. The preparation of W2C and WC was achieved by spin-coating of pre-synthesized W NPs on graphite substrate and following heat treatment under Ar atmosphere at 1000 and 1450°C.
The obtained W2C and WC films were used both in electrochemical water splitting studies. We also made a composite W2C-Pt films where we used only 5 at.% of Pt. The W2C-Pt composite has shown similar performance as pure Pt-C for hydrogen (H2) evolution. In conclusion, we have developed a procedure for the synthesis of W NPs which can be applied for the preparation of tungsten carbides films and their use for electrochemical water splitting.
Found in: osebi
Keywords: water splitting, nanoparticles, hot-matrix
Published: 09.10.2017; Views: 5203; Downloads: 0
Fulltext (376,30 KB) |
10. Photoelectrochemical Water Splitting Studies with nanostructured n and p-type semiconductor electrodesMatjaz Valant, Saim Emin, 2017, published scientific conference contribution abstract (invited lecture) Abstract: Photoelectrochemical water splitting has been demonstrated as a promising way to efficiently split water. Currently, solar-to-hydrogen conversion efficiency using state-of-the-art material combinations in PEC system is in the order of 7%. Fabrication of nanostructured materials with unique morphologies and compositions is an important factor to fully utilize the possibilities in this field. We will present different strategies for the preparation of nanostructured metal oxide thin films by using electrodeposition and wet-chemistry techniques. Focus will be given on the preparation of ZnO and CuO thin films where intermediate phases like Zn(OH)8Cl2.H2O and CuX (X=Br, Cl) were electrodeposited. Wet-chemistry synthesis techniques will be also explored for the preparation of nanostructured WO3 and a-Fe2O3 thin films. Especially, the hot-pyrolysis technique for the preparation of colloidal W and Fe/Fe-oxide nanoparticles will be shown. Spin-coating of W and Fe/Fe-oxide NPs onto optically conductive substrates and subsequent heat treatment of the obtained films was found to be a convenient way for the preparation of nanostructured WO3 and a-Fe2O3 thin films.
Found in: osebi
Keywords: photoelectrochemical water splitting, colloidal nanoparticles, semiconductor
Published: 24.10.2017; Views: 3722; Downloads: 0
Fulltext (1,47 MB) |
