Abstract
As cheap and abundant materials, transitional metal dichalcogenide monolayers have attracted increasing interests for their application as catalysts in hydrogen production. In this work, the hydrogen evolution reduction of doped vanadium disulfide monolayers is investigated based on first-principles calculations. We find that the doping elements and concentration affect strongly the catalytic ability of the monolayer. We show that Ti-doping can efficiently reduce the Gibbs free energy of hydrogen adsorption in a wide range of hydrogen coverage. The catalytic ability of the monolayer at high hydrogen coverage can be improved by low Ti-density doping, while that at low hydrogen coverage is enhanced by moderate Ti-density doping. We further show that it is much easier to substitute the Ti atom to the V atom in the vanadium disulfide (VS2) monolayer than other transitional metal atoms considered here due to its lowest and negative formation energy. It is expected that the Ti-doped VS2 monolayer may be applicable in water electrolysis with improved efficiency.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1182-y) contains supplementary material, which is available to authorized users.
Highlights
Two-dimensional (2D) transitional metal dichalcogenide monolayers have received increasing attention because of their amazing physical, chemical, electronic, and magnetic properties [1,2,3,4,5,6,7,8]
We find that the catalytic activity of the doped VS2 monolayer depends strongly on the choice of dopant and the doping concentration
The catalytic ability of the VS2 monolayer under high hydrogen coverages can be dramatically enhanced by transition metal (TM)-doping at a low concentration, while that under low hydrogen coverages can be improved by the doping at a moderate density
Summary
Two-dimensional (2D) transitional metal dichalcogenide monolayers have received increasing attention because of their amazing physical, chemical, electronic, and magnetic properties [1,2,3,4,5,6,7,8]. The transition-metal dichalcogenides have the formula of MX2 (M is a transition metal element from groups IV to VI, and X is a chalcogen element), where one M-atom layer is sandwiched between two X-atom layers [1] These 2D monolayers have been extensively investigated for possible applications in many areas of science and technology, from nanodevices, photoelectronics, catalysts, to the bioscience [9,10,11,12,13,14,15,16,17]. Pan reported that vanadium disulfide (VS2) monolayer shows the best HER performance in the considered systems and its catalytic activity depends on the hydrogen coverage during HER, which is reduced at high coverage due to the change of conductivity [19]. We show that the doping effect on HER strongly depends on the concentration of dopants
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