Bonde, Jacob Lindner

Chorkendorff, Ib

Horch, Sebastian

Jaramillo, Thomas

Jørgensen, Kristina Pilt

Nielsen, Jane Hvolbæk

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 17, 2017Identification and Quantification of the Active Sites for Hydrogen Evolution on MoS2Nanoparticles.Bonde, Jacob Lindner; Jaramillo, Thomas; Jørgensen, Kristina Pilt; Horch, Sebastian; Nielsen, JaneHvolbæk; Chorkendorff, IbPublished in:Meeting Abstracts - Electrochemical SocietyPublication date:2007Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Bonde, J. L., Jaramillo, T., Jørgensen, K. P., Horch, S., Nielsen, J. H., & Chorkendorff, I. (2007). Identificationand Quantification of the Active Sites for Hydrogen Evolution on MoS2 Nanoparticles. In Meeting Abstracts -Electrochemical Society (pp. Abstract 88). Electrochemical Society, Incorporated.212th ECS Meeting, Abstract #88, © The Electrochemical SocietyIdentification and Quantification of the Active Sites for Hydrogen Evolution on MoS2 Nanoparticles.  Jacob Bonde1, Thomas F. Jaramillo1,  Kristina P. Jørgensen1, Jane H. Nielsen1,  Sebastian Horch2, Ib Chorkendorff1  1 Center for Individual Nanoparticle Functionality, CINF  2 Center for Atomic-scale Materials Design, CAMD  Nano·DTU,   Department of Physics, Building 312 and 307,  Technical University of Denmark,  DK-2800 Lyngby, Denmark   A possible future energy carrier under consideration is H2, which can be produced cleanly and renewably if solar or wind energy is coupled to water electrolysis.  Unfortunately, the Hydrogen Evolution Reaction (HER) is catalyzed most effectively by the Pt group metals – materials that are expensive and scarce. New materials are needed if this scheme is to ever become viable.   It has recently been proposed that the activity of HER electrocatalysts is governed by a simple descriptor: the free energy of hydrogen adsorption (∆GH). The activity follows the Sabatier principle with high catalytic activity at ∆GH≈0 [1]. The predictor can be calculated by Density Functional Theory (DFT), which opens new possibilities in terms of finding alternative HER catalysts [2].  Another system where the free energy of hydrogen adsorption ∆GH is close to zero is nanoparticulate MoS2. The active sites of MoS2 are solid state analogs to the active sites on hydrogen evolving enzymes like hydrogenase. Preliminary results showed that hydrogen in fact was evolved on graphite supported nanoparticulate MoS2 at a low overpotential [3].       Figure 1. STM images of MoS2 particles on Au(111).   In order to investigate the MoS2 in more detail we have measured activity for the HER of UHV prepared and atomically imaged (with a scanning tunnelling microscope) MoS2 nanoparticles on Au(111). This made it possible to quantify the distribution of different sites present on the samples and compare that with the HER activity. On the MoS2 model system (see Figure 1) there generally exists two different sites the terrace site and the edge site(predicted to be active for HER in [3]). Measurements of the HER on samples with different coverage and particle size showed that the activity only correlated with the edge length of the particles.  Thus we conclude that the edge indeed is the active site for HER on nanoparticulate MoS2, this also allows us to compare the activity of MoS2 to that of the pure metals plotted on the volcano in [1] and we find that the activity is below that of the Pt group metals and above that of the more common metals.  Investigations of the graphite supported nanoparticlulate MoS2/C investigated in [3] were also conducted. It was found that an irreversible oxidation of the MoS2/C takes place at anodic potentials (approx. 0.8 V vs. NHE). This oxidation severely inhibited the activity of the active sites for HER on the MoS2/C.    The irreversible oxidation shows up as a well-defined peak in the cyclic voltammogram and we were able to use this peak to quantify the amount of MoS2/C present on the sample. Activity per site of MoS2/C was then compared to that of MoS2 on Au(111), preliminary results show that these activities are indeed comparable.   We have established that the irreversible oxidation method can be used to quantify the amount of nanoparticulate supported MoS2. Results on other metal sulfides will also be presented.  References   [1] J.K. Nørskov, T. Bligaard, A. Logadottir, J.R. Kitchin, J.G. Chen, S. Pandelov, U. Stimming,   “Trends in the Exchange Current for Hydrogen Evolution” J. Electrochem. Soc. (152), J23 (2005).  [2]  J. Greeley, T. F. Jaramillo, J. Bonde, I. Chorkendorff, and J. K. Nørskov, “Computational High-Throughput Screening of Electrocatalytic Materials for Hydrogen Evolution ” Nature Materials, (11) 909–913(2006).  [3] B. Hinnemann, P. G. Moses, J. Bonde, K. P. Jørgensen, J. H. Larsen, S. Horch, I. Chorkendorff, J.K. Nørskov, ”Biomimetic Hydrogen Evolution”, J. Am. Chem. Soc., (127) 5308-5309  (2005).   7 nm 80 nm 

Identification and Quantification of the Active Sites for Hydrogen Evolution on MoS2 Nanoparticles.

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Identification and Quantification of the Active Sites for Hydrogen Evolution on MoS2 Nanoparticles.

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