Group VB transition metal dichalcogenides for oxygen reduction reaction and strain-enhanced activity governed by p-orbital electrons of chalcogen
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Developing alternative oxygen reduction reaction (ORR) catalysts to replace precious Pt-based metals with abundant materials is the key challenge of commercial application of fuel cells. Owing to their various compositions and tunable electronic properties, transition metal dichalcogenides (TMDs) have the great potential to realize high-efficiency catalysts for ORR. Here, various 3R-phase dichalcogenides of group VB and VIB transition metals (MX2, M = Nb, Ta, Mo, W; X = S, Se, Te) are investigated for ORR catalysts by using density functional theory calculations. The computed over-potentials of group VB TMDs are much less than those of group VIB TMDs. For group VB TMDs, a volcano-type plot of ORR catalytic activity is established on the adsorption energies of *OH, and NbS2 and TaTe2 exhibit best ORR activity with an over-potential of 0.54 V. To achieve even better activity, strain engineering is performed to tune ORR catalytic activity, and the minimum over-potential of 0.43 V can be realized. We further demonstrate that the shift of p orbital center of surface chalcogen elements under strain is responsible for tuning the catalytic activity of TMDs.
Keywordstransition metal dichalcogenides fuel cells oxygen reduction reaction strain density functional theory (DFT) calculations
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This work was supported by the National Key Research and Development Program of China (No. 2017YFB0701600), the National Natural Science Foundation of China (Nos. 11874036, 51622103, and 21573123), the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01N111), Shenzhen Projects for Basic Research (No. JCYJ20170412171430026), and the National Program for Thousand Young Talents of China. Tianjin Supercomputing Center is also acknowledged for allowing the use of computational resources including TIANHE-1.
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