Yazar "Zia-ur-Rehman" seçeneğine göre listele

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    Öğe
    Solar light driven photoelectrochemical water splitting using Mn-doped CdS quantum dots sensitized hierarchical rosette-rod TiO2 photoanodes
    (Elsevier Science Sa, 2022) Ahmad, Abrar; Tezcan, Fatih; Yerlikaya, Gurbet; Zia-ur-Rehman; Paksoy, Halime; Kardas, Gulfeza
    Herein we investigated the photoelectrochemical performance of manganese (Mn) doped cadmium sulfide (CdS) quantum dots (QDs) decorated onto the surface of hierarchical double-layered rosette-rod titanium dioxide (TiO2) photoanode. The rosette-rod TiO2 architectures are synthesized by two steps hydrothermal process while Mn-doped CdS QDs deposition is taken out by successive ionic layer adsorption and reaction (SILAR) approach. Two different kinds of structures exist simultaneously in rosette-rod TiO2, one-dimensional TiO2 nanorod arrays present at the bottom, while the upper three-dimensional nano rosette consists of small TiO2 nanorods as building units. Photoelectrochemical performance of the as-prepared photoanodes are explored in terms of photocurrent density and applied biased to photon conversion efficiency by varying Mn concentration and the number of SILAR cycles to find the best performing photoanodes. Linear sweep voltammetry results show that 35 mM shows the maximum photo-current density of 2.12 mA cm(-2) at 1.23 VRHE with a maximum photoconversion efficiency of similar to 1.61% at 0.4 VRHE, while 8 numbers of SILAR cycles shows the highest photo current-density of 2.73 mA cm(-2) at 1.23 VRHE and maximum photoconversion efficiency of 2.19% at 0.2 V-RHE.
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    Öğe
    The investigation of CdS-quantum-dot-sensitized Ag-deposited TiO2 NRAs in photoelectrochemical hydrogen production
    (Royal Soc Chemistry, 2022) Tezcan, Fatih; Ahmad, Abrar; Yerlikaya, Gurbet; Zia-ur-Rehman; Paksoy, Halime; Kardas, Gulfeza
    Photoelectrochemical hydrogen production using photoelectrodes with sophisticated hierarchical architecture designs combined with effective photoactive materials, has been found to be an impressive route for achieving high photoelectrocatalytic efficiency. Here, we investigated the photoelectrocatalytic hydrogen production of CdS quantum dot (QD)-sensitized TiO2 nanorod arrays (NRAs) decorated with Ag nanoparticles synthesized using simple and cost-effective routes. TiO2 NRAs were grown on a fluorine-doped tin oxide (FTO) substrate via a hydrothermal method, followed by loading with Ag nanoparticles and deposition of CdS QDs using electrochemical and successive ionic layer adsorption and reaction (SILAR) approaches. In this arrangement, the Ag nanoparticles were found to be sandwiched between the photo-electron collector TiO2 and the photosensitizer CdS QDs that act as an electron relay, thus speeding the electron transport and improving photogenerated charge separation. CdS QDs significantly enhance the solar light absorption capability of the photoelectrode from the ultraviolet to the visible portion of the solar spectrum, improving the photoconversion efficiency. The surface morphology and optical properties of the as-prepared photoanodes were investigated using scanning electron microscopy and a UV-vis spectrometer. Scanning electron microscopy (SEM) images confirm that increasing the number of SILAR cycles caused agglomeration of the CdS QDs on the TiO2 NRAs surface. Photoelectrochemical hydrogen production performance was investigated with linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) under simulated solar light of 100 mW cm(-2). The LSV results confirm that the bare TiO2 NRAs exhibit a maximum photocurrent density of 0.17 mA cm(-2) at 1.23 V-RHE. However, upon the deposition of CdS QDs, an optimum photocurrent density of 0.623 mA cm(-2) at 1.23 V-RHE was observed for the 10 SILAR cycle samples, which was further improved to 0.931 mA cm(-2) at 1.23 V-RHE upon the introduction of Ag nanoparticles.