Researcher:
Ullah, Haseeb

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Haseeb

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Ullah

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Ullah, Haseeb

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20213

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Researcher Of Publications: search.filters.isAuthorOfPublication.25995e8c-a992-42ec-be8e-f97b85a6b45c

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    Surfactant-free synthesis of CdS nanorods for efficient reduction of carcinogenic Cr(VI)
    (Taylor and Francis Ltd, 2021) Butler, Ian S.; Rehman, Zia Ur; N/A; N/A; Department of Chemistry; Ullah, Haseeb; Balkan, Timuçin; Kaya, Sarp; Researcher; Other; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; College of Sciences; N/A; N/A; 116541
    Hexavalent chromium, Cr(VI), is a toxic, mutagenic and carcinogenic species. We report here the semiconductor-based, photocatalytic reduction of Cr(VI) to trivalent chromium, Cr(III), using CdS nanorods (NRs) as the photocatalyst under visible light illumination. The CdS NRs were synthesized by a facile and scalable solvothermal method in which ethylenediamine acts as solvent and morphology controller. The CdS NRs produced were studied by PXRD, Raman, FESEM, EDX, XPS, PL, UV-visible DRS and BET techniques in order to investigate their structural, morphological and optical properties, as well as their porosity. The photoreduction of Cr(VI) to Cr(III) under visible light illumination was performed under a variety of conditions, i.e., varying the irradiation time, pH, substrate concentration, and the amount of photocatalyst. The maximum photoreduction of Cr(VI) to Cr(III) (99%) was achieved using 60 min of irradiation under acidic conditions (pH 4). The excellent photoreduction ability of the CdS NRs can be attributed to their rod-like structure together with their small particle size, large surface area, and clean surfaces. These properties enhanced separation of the photo-generated electron-hole pairs, which was confirmed by the XRD, BET, and PL measurements. In addition, the results of a kinetic study indicated that the photoreduction of Cr(VI) to Cr(III) follows a pseudo-first-order kinetic model. A possible mechanism for the photocatalytic reduction of Cr(VI) to Cr(III) is also proposed in this paper.
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    Green synthesis of mesoporous MoS2 nanoflowers for efficient photocatalytic degradation of Congo red dye
    (Taylor & Francis, 2021) Khan, Zaibunisa; Nasir, Jamal Abdul; Butler, Ian S.; Rehman, Zia Ur; N/A; Department of Chemistry; N/A; Ullah, Haseeb; Kaya, Sarp; Balkan, Timuçin; N/A; Faculty Member; Other; Department of Chemistry; N/A; College of Sciences; N/A; N/A; 116541; N/A
    A one-step, facile and scalable hydrothermal route was employed to synthesize molybdenum disulfide (MoS2) nanoflowers (NFs) for use in the photodegradation of Congo red (CR) dye. The phase purity, morphology, and structural features of the produced mesoporous MoS2-NFs were examined using PXRD, FESEM, EDX, XPS, BET, Raman and UV-visible DRS techniques. The nitrogen adsorption-desorption isotherms display a clear H-3-type of hysteresis loop at P/P-o of 0.8-1.0, which affords an insight into the mesoporous nature of the MoS2 NFs with a pore diameter of 1.5 to 40 nm. The mesoporous MoS2 NFs showed excellent CR degradation activity under solar light irradiation with a K-app of 0.76 x 10(-2 )min(-1). Importantly, the results showed a notable impact of reaction media on the degradation of CR suggesting that pH 7 is a favorable medium for this particular catalytic reaction. A kinetic study has illustrated that photodegradation of CR follows pseudo-first order kinetics. This work illustrates that mesoporous MoS2 NFs can be used as an efficient photocatalyst for the degradation of highly toxic and hazardous organic dyes in environmental remediation.
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    Scaling-up photocatalytic activity of CdS from nanorods to nanowires for the MB degradation
    (Elsevier, 2021) Rehman, Zia ur; N/A; N/A; N/A; Department of Chemistry; Ullah, Haseeb; Barzgarvishlaghi, Mahsa; Balkan, Timuçin; Kaya, Sarp; Researcher; PhD Student; Other; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; Graduate School of Sciences and Engineering; N/A; College of Sciences; N/A; N/A; N/A; 116541
    The development of a scalable and facile method for the synthesis of visible light driven photocatalytic materials to degrade toxic organic dyes is highly challenging and essential. In this regards, cadmium sulfide (CdS) nanorods and nanowires with controlled aspect ratio, grain size, surface area, and bandgap were synthesized by a simple solvothermal method, and their photocatalytic performances were exploited for the photo-degradation of methylene blue (MB) under simulated solar light. Extensive structural characterizations to identify the origin of the activities were performed. The photocatalytic activity measurements showed that the degradation of MB was 94.41%, 97.24%, 97.88%, and 99.82% for CdS prepared by following four different synthesis routes and increasing trend showed a correlation with the nanostructure morphology changing from nanorod and nanowires with increasing aspect ratio. It has been found that CdS nanowires show more pronounced photocatalytic activity due to the efficient separation of photo-generated electron-hole pairs induced by increased the aspect ratio and higher active surface area.