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Engineering the Composition and Crystallinity of Molybdenum Sulfide for High-Performance Electrocatalytic Hydrogen Evolution

Li, Yanpeng and Yu, Yifei and Nielsen, Robert J. and Goddard, William A., III and Li, Yao and Cao, Linyou (2015) Engineering the Composition and Crystallinity of Molybdenum Sulfide for High-Performance Electrocatalytic Hydrogen Evolution. ACS Catalysis, 5 (1). pp. 448-455. ISSN 2155-5435.

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The key challenge for the development of high-performance molybdenum sulfide HER catalysts lies in the limited fundamental understanding for the correlation between the catalytic activities and physical features of the materials. Here we have demonstrated an unambiguous correlation between the catalytic performance and the composition/crystallinity of molybdenum sulfide. The results indicate that the crystallinity plays an overwhelming role in determining the catalytic performance, while the composition does not matter much. The crystallinity can affect the three figures of merit of the catalytic performance (Tafel slope, turnover frequency (TOF), and stability) in opposite directions. Generally, the materials with low crystalline quality may provide low Tafel slopes (∼40 mV/dec), while highly crystalline molybdenum sulfide shows higher TOFs (by 2 orders of magnitude) and better stability. DFT calculations suggest that the terminal disulfur complex S-2^(2–), which may exist in MoS_3 and also likely MoS_2 of low crystalline quality due to its structural disorder, could be the true catalytically active site responsible for the low Tafel slope. Our results indicate that one key issue for the rational design of high-performance molybdenum sulfide HER catalysts is to engineer the crystallinity such that balancing its contradictory effects on the different aspects of the catalytic performance. We show that nanocrystalline MoS_2 with few-layer nanoclusters in a lateral size of 5–30 nm provides a more promising platform than either amorphous or highly crystalline molybdenum sulfide due to its combination of low Tafel slopes and good stability. As a way to illustrate this notion, we have developed a MoS_2 catalyst by engineering the crystallinity that shows Tafel slopes of 40 mV/dec, exchange current densities of 3.5 μA/cm^2, and extraordinary stability with constant performance over >10000 cycles, which are among the best values ever reported. The performance of this catalyst could be further improved by using rougher substrates or doping to improve the relatively low exchange current density.

Item Type:Article
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URLURL TypeDescription ItemSupporting Information
Nielsen, Robert J.0000-0002-7962-0186
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2014 American Chemical Society. Received: October 23, 2014. Revised: November 26, 2014. Publication Date (Web): December 4, 2014. This work was supported as part of the Center for the Computational Design of Functional Layered Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0012575. The authors acknowledge useful discussions with S. Y. Huang and the use of the Analytical Instrumentation Facility (AIF) at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation. The computational studies by Y.H., R.A.N., and W.A.G. were supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0012575
State of North CarolinaUNSPECIFIED
Department of Energy (DOE)DE-SC0004993
Subject Keywords:molybdenum disulfide, molybdenum trisulfide, disulfur complex, nanocrystalline, oxidation
Issue or Number:1
Record Number:CaltechAUTHORS:20150220-114356227
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Official Citation:Engineering the Composition and Crystallinity of Molybdenum Sulfide for High-Performance Electrocatalytic Hydrogen Evolution Yanpeng Li, Yifei Yu, Yufeng Huang, Robert A. Nielsen, William A. Goddard, III, Yao Li, and Linyou Cao ACS Catalysis 2015 5 (1), 448-455
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55052
Deposited By: Ruth Sustaita
Deposited On:20 Feb 2015 21:11
Last Modified:03 Oct 2019 08:02

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