Catalytic Activities of Sulfur Atoms in Amorphous Molybdenum Sulfide for the Electrochemical Hydrogen Evolution Reaction

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• 作者：Louisa Rui Lin Ting ; Yilin Deng ; Liang Ma ; Yin-Jia Zhang ; Andrew A. Peterson ; Boon Siang Yeo
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：February 5, 2016
• 年：2016
• 卷：6
• 期：2
• 页码：861-867
• 全文大小：537K
• ISSN：2155-5435

文摘

The catalytic activities of sulfur sites in amorphous MoS_x for the electrochemical hydrogen evolution reaction (HER) was investigated in aqueous 0.5 M H₂SO₄ electrolyte. Using X-ray photoelectron spectroscopy and linear sweep voltammetry, we found the turnover frequency for H₂ production to increase linearly with the percentage of S atoms with higher electron binding energies. These S atoms could be apical S^2– and/or bridging S₂^2–. To distinguish the catalytic performances of these two types of atoms, we turn to quantum chemical simulations using density functional theory. The apical S^2– atoms were found to adsorb H weakly with a Gibbs free energy for atomic H adsorption (ΔG_H) in excess of +1 eV, and were thus ruled out as reaction sites for HER. In situ Raman spectroscopy of the model [Mo₃S₁₃]^2– cluster further demonstrate the higher catalytic reactivity of the bridging S₂^2– over terminal S₂^2– (which have lower electron binding energy) for proton reduction.