The Synthesis and Electrocatalytic Activities of Molybdenum Sulfide for Hydrogen Evolution Reaction

Handle URI:
http://hdl.handle.net/10754/324122
Title:
The Synthesis and Electrocatalytic Activities of Molybdenum Sulfide for Hydrogen Evolution Reaction
Authors:
Li, Zhengxing
Abstract:
In the context of the future hydrogen economy, effective production of hydrogen (H2) from readily available and sustainable resources is of crucial importance. Hydrogen generation via water splitting by solar energy or electricity has attracted great attention in recent years. In comparison with photocatalytic water-splitting directly using solar light, which is ideal but the relevant technologies are not yet mature, electrolysis of water with catalyst is more practical at the current stage. The Pt-group noble metals are the most effective electrocatalysts for hydrogen evolution reaction (HER) from water, but their high costs limit their applications. Due to the earth-abundance and low price, MoS2 is expected to be a good alternative of the Pt-group metals for HER. Plenty of researches have been conducted for improving the HER activities of MoS2 by optimizing its synthesis method. However, it remains challenging to prepare MoS2 catalysts with high and controllable activity, and more investigations are still needed to better understand the structure-performance correlation in this system. In this thesis, we report a new strategy for fabricating MoS2 eletrocatalysts which gives rise to much improved HER performance and allows us to tune the electrocatalytic activity by varying the preparation conditions. Specifically, we sulfurized molybdenum oxide on the surface of a Ti foil electrode via a facile chemical vapor deposition (CVD) method, and directly used the electrode for HER testing. Depending on the CVD temperature, the MoO2-MoS2 nanocomposites show different HER activities. Under the optimal synthesis condition (400ºC), the resulting catalyst exhibited excellent HER activity: an onset potential (overpotential) of 0.095 V versus RHE and the Tafel slope of 40 mv/dec. Such a performance exceeds those of most reported MoS2 based HER electrocatalysts. We demonstrated that the CVD temperature has significant influence on the catalysts in crystallinity degree, particle size and dispersion, morphology, and density of the edge sites etc., and these factors in turn determine the HER activity.
Advisors:
Han, Yu ( 0000-0003-1462-1118 )
Committee Member:
Khashab, Niveen ( 0000-0003-2728-0666 ) ; Wu, Tom (Tao)
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Chemical Sciences
Issue Date:
Jul-2014
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Chemical Science Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorHan, Yuen
dc.contributor.authorLi, Zhengxingen
dc.date.accessioned2014-08-04T11:22:13Z-
dc.date.available2014-08-04T11:22:13Z-
dc.date.issued2014-07en
dc.identifier.urihttp://hdl.handle.net/10754/324122en
dc.description.abstractIn the context of the future hydrogen economy, effective production of hydrogen (H2) from readily available and sustainable resources is of crucial importance. Hydrogen generation via water splitting by solar energy or electricity has attracted great attention in recent years. In comparison with photocatalytic water-splitting directly using solar light, which is ideal but the relevant technologies are not yet mature, electrolysis of water with catalyst is more practical at the current stage. The Pt-group noble metals are the most effective electrocatalysts for hydrogen evolution reaction (HER) from water, but their high costs limit their applications. Due to the earth-abundance and low price, MoS2 is expected to be a good alternative of the Pt-group metals for HER. Plenty of researches have been conducted for improving the HER activities of MoS2 by optimizing its synthesis method. However, it remains challenging to prepare MoS2 catalysts with high and controllable activity, and more investigations are still needed to better understand the structure-performance correlation in this system. In this thesis, we report a new strategy for fabricating MoS2 eletrocatalysts which gives rise to much improved HER performance and allows us to tune the electrocatalytic activity by varying the preparation conditions. Specifically, we sulfurized molybdenum oxide on the surface of a Ti foil electrode via a facile chemical vapor deposition (CVD) method, and directly used the electrode for HER testing. Depending on the CVD temperature, the MoO2-MoS2 nanocomposites show different HER activities. Under the optimal synthesis condition (400ºC), the resulting catalyst exhibited excellent HER activity: an onset potential (overpotential) of 0.095 V versus RHE and the Tafel slope of 40 mv/dec. Such a performance exceeds those of most reported MoS2 based HER electrocatalysts. We demonstrated that the CVD temperature has significant influence on the catalysts in crystallinity degree, particle size and dispersion, morphology, and density of the edge sites etc., and these factors in turn determine the HER activity.en
dc.language.isoenen
dc.subjectElectrocatalysisen
dc.subjectHERen
dc.subjectChemical vapor depositionen
dc.subjectHydrothermal Synthesisen
dc.subjectmolybolenum sulfideen
dc.subjecttemperature influenceen
dc.titleThe Synthesis and Electrocatalytic Activities of Molybdenum Sulfide for Hydrogen Evolution Reactionen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberKhashab, Niveenen
dc.contributor.committeememberWu, Tom (Tao)en
thesis.degree.disciplineChemical Sciencesen
thesis.degree.nameMaster of Scienceen
dc.person.id124185en
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