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    Molybdenum Disulfide as an Efficient Catalyst for Hydrogen Evolution Reaction

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    Name:
    Abeer Alarawi - Dissertation - Final Draft.pdf
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    Abeer Alarawi - Dissertation - Final Draft
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    Type
    Dissertation
    Authors
    Alarawi, Abeer A. cc
    Advisors
    He, Jr-Hau cc
    Committee members
    Di Fabrizio, Enzo M. cc
    Han, Yu cc
    Jin, Song
    Program
    Material Science and Engineering
    KAUST Department
    Physical Science and Engineering (PSE) Division
    Date
    2018-12-02
    Permanent link to this record
    http://hdl.handle.net/10754/630133
    
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    Abstract
    Hydrogen is a carrier energy gas that can be utilized as a clean energy source instead of oil and natural gas. Splitting the water into hydrogen and oxygen is one of the most favorable methods to generate hydrogen. The catalytic properties of molybdenum disulfide (MoS2) could be valuable in this role, particularly due to its unique structure and ability to be chemically modified, enabling its catalytic activity to be further enhanced or made comparable to that of Pt-based materials. In general, these modification strategies may involve either structural engineering of MoS2 or enhancing the kinetics of charge transfer, including by confining to single metal atoms and clusters or integrating with a conductive substrate. We present the results of synergetic integration of MoS2 films with a Si-heterojunction solar cell for generating H2 via the photochemical water splitting approach. The results of the photochemical measurements demonstrated an efficient photocurrent of 36. 3 mA cm-2 at 0 V vs. RHE and an onset potential of 0.56 V vs. RHE. In addition to 25 hours of continuous photon conversion to H2 generation, this study points out that the integration of the Si-HJ with MoS2 is an effective strategy for enhancing the internal conductivity of MoS2 towards efficient and stable hydrogen production. Moreover, we studied the effect of doping an atomic scale of Pt on the catalytic activity of MoS2. The electrochemical results indicated that the optimum single Pt atoms loading amount demonstrated a distinct enhancement in the hydrogen generating, in which the overpotential was minimized to -0.0505 V to reach a current density of 10 mA cm−2 using only 10 ALD cycles of Pt. The Tafel slopes of the ALD Pt/ML-MoS2 electrodes were in the range of 55–120 mV/decade, which indicates a fast improvement in the HER velocity as a result of the increased potential. Stability is another important parameter for evaluating a catalyst. The same (10 ALD cycles) Pt/ML-MoS2 electrode was able to continuously generate hydrogen molecules at for 150 hours. These superior results demonstrate that the low conductivity of semiconductive MoS2 can be enhanced by anchoring the film with Pt SAs and clusters, leading to sufficient charge transport and a decrease in the overpotential.
    Citation
    Alarawi, A. A. (2018). Molybdenum Disulfide as an Efficient Catalyst for Hydrogen Evolution Reaction. KAUST Research Repository. https://doi.org/10.25781/KAUST-2ILCQ
    DOI
    10.25781/KAUST-2ILCQ
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-2ILCQ
    Scopus Count
    Collections
    Dissertations; Physical Science and Engineering (PSE) Division; Material Science and Engineering Program

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