白金及其相關的複合材料應用在電催化觸媒有極佳的效果，但成本昂貴致使無法廣泛應用，因此硫化鉬偕其成本低、化學穩定性高以及其層狀結構能夠提供豐富的活性部位之優點，在電催化產氫方面有極大的吸引力。本研究以水熱法製備硫化鉬薄膜，並於製程中添加葡萄糖，將其應用在電化學產氫，探討碳源的加入對於硫化鉬薄膜電化學產氫效果之影響。研究結果顯示，隨著葡萄糖添加的量增加，硫化鉬薄膜的片狀堆疊變得較緊密，表面起伏較明顯。而添加葡萄糖會使硫化鉬鍵結組成有部分改變，除了Mo4+以及S2-亦有Mo6+以及S22-存在。由Tafel plot所得之斜率沒有極大改變，所以產氫的主要的機制與速率決定步驟不因添加葡萄糖有變化。當葡萄糖添加量為0.12 g時，有最佳的電流表現，起始電壓較小，交換電流密度較大，電子傳輸較快，於電化學產氫反應的效能最好 。

Hydrothermal Synthesis of Molybdenum Sulfide Films for the Application to Electrochemical Hydrogen Evolution

Yu-Min Chang
Jih-Jen Wu
Department of Chemical Engineering, National Cheng Kung University

SUMMARY
Molybdenum sulfide/carbon composite films were hydrothermally grown on the TiO2-seeded FTO substrates. The morphology of the films, distance between molybdenum sulfide nanosheets, and chemical state of Mo and S were changed as adjusting the amount of glucose addition in the precursor. The performance of electrochemical hydrogen evolution of the molybdenum sulfide/carbon electrodes including current density, onset potential, exchange current density, and charge transfer were optimized in terms of the amount of glucose addition.
Key words: electrocatalyst, molybdenum sulfide, electrochemical hydrogen evolution

INTRODUCTION

The development of electrocatalyst has attracted considerable interest for the use in energy technologies based on chemical conversion reactions. The electrocatalysts of Pt-based materials for the hydrogen evolution reaction (HER) are highly efficient. However, the high cost of Pt catalysts restricts its large-scale application. Recently, molybdenum sulfide which is earth-abundant and low-cost has been investigated as a promising electrocatalyst for H2 evolution. Molybdenum sulfide possesses layer structure composed of S-Mo-S sandwich structure and linked by van der Waals interaction. Two general types of surface sites are present on the layer structure, including terrace sites on the basal planes and edge sites on the side surfaces. The edge sites of molybdenum sulfide are the active sites for HER. Moreover, molybdenum sulfide is catalytically active in the solutions with a wide range of the pH value. A relatively low overvoltage is required for H2 evolution by using molybdenum sulfide.

Syntheses of molybdenum sulfide have been reported by using ultrahigh-vacuum processing, high-temperature treatment, electrodeposition, wet chemical route, solvothermal method, and hydrothermal method. To circumvent the conductivity limitation of molybdenum sulfide which affects charge transport, molybdenum sulfide/carbon composites were used to further enhance the performance of HER. In this work, molybdenum sulfide/carbon composite films were hydrothermally grown on FTO substrates by using glucose as carbon source. The structures and HER performances of molybdenum sulfide/carbon composite films were investigated.

MATERIALS AND METHODS
Materials
NaMoO4．2H2O (99.9%), glucose(99%), and ethanol(99.9%) were purchased from J.T. Baker. Thiourea(99%) and hydrochloride acid(37%) were purchased from Sigma-Aldrich. Titanium tetrachloride(98%) was obtained from fluka.

Synthesis of molybdenum sulfide/carbon composite
To form TiO2 seeds on FTO substrates. FTO substrate was immersed in 0.5M TiCl4 and kept at 50°C for 1 h. The mixture which contained 0.1936g of NaMoO4．2H2O, 0.3045g of thiourea and 0.06g/0.09g/0.12g of glucose was dissolved in 24 ml DI water and 6 ml ethanol in an autoclave. Subsequently, the FTO/ TiO2 seed was immersed in the mixture and reacted in 190°C for 3h. The autoclave was cooled to room temperature and then MoS2-C was rinsed by DI water and dried by N2.

Characterization techniques
The morphology of the molybdenum sulfide/carbon composite films was examined by scanning electron microscopy (FESEM, JSM-6700F). The structures of the molybdenum sulfide/carbon composite films were investigated by transmission electron microscopy (TEM, FEI E.O Tecnai F20 G2 MAT S-TWIN) and Raman spectroscopy (BWII RAMaker). The binding states of Mo, S, C and O for the molybdenum sulfide/carbon composite films were performed by X-ray photoelectron spectroscopic (XPS, JEOL JAMP-9500F).

RESULTS AND DISCUSSION

Figures 1a and 1d are the SEM images of the MoS2 and MoS2-C(0.12g) films, respectively, which show rough and granular surfaces of the films. The high-magnification SEM images indicate that the MoS2 and MoS2-C(0.12g) films are composed of stacked nanosheets (Figure 1b and 1e). Additionally, the molybdenum sulfide nanosheets cluster together (Figure 1c and 1f) and the surface undulate obviously in the MoS2-C(0.12g) film. As shown in figure 2, HRTEM images reveal that the molybdenum sulfide nanosheets are composed of a few molybdenum sulfide layers with an interlayer distance of 0.64 nm. Besides, the crystallinity of the MoS2-C(0.12g) film is worse than that of the MoS2 film.

The structure of molybdenum sulfide/carbon composites were characterized by Raman spectroscopy. Two Raman peaks at 382 and 407 cm-1 are corresponding to the E12g and A1g vibration modes of hexagonal molybdenum disulfide, respectively.(Figure 3) The frequency difference (Δk) of the two Raman modes (E12g and A1g) is used to identify the layer number. The 25 cm-1 difference of the MoS2 film is well correlated with the bulk molybdenum disulfide. The frequency differences the two characteristic Raman modes decrease slightly as increasing carbon content which suggest the fewer layer numbers of molybdenum sulfide nanosheets in the molybdenum sulfide/carbon composite films.

The binding states of molybdenum sulfide films were investigated by XPS. Figure 4a confirms the elemental compositions of Mo, S, C, and O in the MoS2-C(0.12g) film. The strongest Mo 3d5/2 signal comes from the characteristic of a 4+ oxidation state as shown in Figure 4c. The shoulders attribute to the higher +6 oxidation state, probably due to the formation of MoO3 during hydrothermal process and after exposing to air. The presence of bridging S22- and S2- states are shown in S 2p region. (Figure 4d )

The polarization curves of the MoS2-C films are shown in figure 5a which reveal that the MoS2-C(0.12g) film exists highest current densities for HER. The linear portions of the Tafel plots all yield Tafel slopes of ≈ 55 mV decade–1 indicating that the main HER mechanism and rate-determining step do not change as varying the carbon content (Figure 5b). Besides, the MoS2-C(0.12g) film shows the lowest onset potential and highest exchange current density. Figure 6 shows the Nyquist plots of the EIS response of the MoS2 and MoS2-C(0.12g) films. The charge transfer resistance Rct values of the MoS2-C(0.12g) film is lower than that of the MoS2 film, which illustrated the superior electrocatalytic activity of the MoS2-C(0.12g) film .

CONCLUSION

Molybdenum sulfide/carbon composite films were hydrothermally grown on the TiO2-seeded FTO substrates. The morphology of the films, distance between molybdenum sulfide nanosheets, and chemical state of Mo and S are changed as adjusting the amount of glucose addition in the precursor. The performance of electrochemical hydrogen evolution of the molybdenum sulfide/carbon electrodes including current density, onset potential, exchange current density, and charge transfer were optimized in terms of the amount of glucose addition.

1. 市川聖, 圖解氫能源. (2007).
2. 曲新生, 陳發林, 呂錫民, 產氫與儲氫技術. (2007).
3. A. S. Huq, A. J. Rosenberg, Electrochemical Behavior of Nickel Compounds I. The Hydrogen Evolution Reaction on, and Their Constituent Elements. Journal of The Electrochemical Society 111, 270-278 (1964).
4. N. Krstajić, V. Jović, L. Gajić-Krstajić, B. Jović, A. Antozzi, G. Martelli, Electrodeposition of Ni–Mo alloy coatings and their characterization as cathodes for hydrogen evolution in sodium hydroxide solution. International Journal of Hydrogen Energy 33, 3676-3687 (2008).
5. L. Birry, A. Lasia, Studies of the hydrogen evolution reaction on Raney nickel—molybdenum electrodes. Journal of applied electrochemistry 34, 735-749 (2004).
6. E. Endoh, H. Otouma, T. Morimoto, Y. Oda, New Raney nickel composite-coated electrode for hydrogen evolution. International journal of hydrogen energy 12, 473-479 (1987).
7. V. Marinović, J. Stevanović, B. Jugović, M. Maksimović, Hydrogen evolution on Ni/WC composite coatings. Journal of applied electrochemistry 36, 1005-1009 (2006).
8. L. Meda, G. Tozzola, A. Tacca, G. Marra, S. Caramori, V. Cristino, C. Alberto Bignozzi, Photo-electrochemical properties of nanostructured WO3 prepared with different organic dispersing agents. Solar Energy Materials and Solar Cells 94, 788-796 (2010).
9. N. Gaillard, B. Cole, J. Kaneshiro, E. L. Miller, B. Marsen, L. Weinhardt, M. Bär, C. Heske, K.-S. Ahn, Y. Yan, Improved current collection in WO3: Mo/WO3 bilayer photoelectrodes. Journal of Materials Research 25, 45-51 (2010).
10. M. Bar, L. Weinhardt, B. Marsen, B. Cole, N. Gaillard, E. Miller, C. Heske, Mo incorporation in WO3 thin film photoanodes: Tailoring the electronic structure for photoelectrochemical hydrogen production. Applied Physics Letters 96, 032107-032107-032103 (2010).
11. S. W. Boettcher, E. L. Warren, M. C. Putnam, E. A. Santori, D. Turner-Evans, M. D. Kelzenberg, M. G. Walter, J. R. McKone, B. S. Brunschwig, H. A. Atwater, Photoelectrochemical hydrogen evolution using Si microwire arrays. Journal of the American Chemical Society 133, 1216-1219 (2011).
12. S. W. Boettcher, J. M. Spurgeon, M. C. Putnam, E. L. Warren, D. B. Turner-Evans, M. D. Kelzenberg, J. R. Maiolo, H. A. Atwater, N. S. Lewis, Energy-conversion properties of vapor-liquid-solid–grown silicon wire-array photocathodes. Science 327, 185-187 (2010).
13. O. Khaselev, J. A. Turner, A monolithic photovoltaic-photoelectrochemical device for hydrogen production via water splitting. Science 280, 425-427 (1998).
14. O. Khaselev, J. A. Turner, Electrochemical Stability of p‐GaInP2 in Aqueous Electrolytes Toward Photoelectrochemical Water Splitting. Journal of the Electrochemical Society 145, 3335-3339 (1998).
15. T. G. Deutsch, J. L. Head, J. A. Turner, Photoelectrochemical characterization and durability analysis of GaInPN epilayers. Journal of The Electrochemical Society 155, B903-B907 (2008).
16. X. Li, W. Cai, J. An, S. Kim, J. Nah, D. Yang, R. Piner, A. Velamakanni, I. Jung, E. Tutuc, Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324, 1312-1314 (2009).
17. A. Reina, X. Jia, J. Ho, D. Nezich, H. Son, V. Bulovic, M. S. Dresselhaus, J. Kong, Large area, few-layer graphene films on arbitrary substrates by chemical vapor deposition. Nano letters 9, 30-35 (2008).
18. J. Hass, W. De Heer, E. Conrad, The growth and morphology of epitaxial multilayer graphene. Journal of Physics: Condensed Matter 20, 323202 (2008).
19. R. Venkatasubramanian, E. Siivola, T. Colpitts, B. O'quinn, Thin-film thermoelectric devices with high room-temperature figures of merit. Nature 413, 597-602 (2001).
20. Y. Y. Li, G. Wang, X. G. Zhu, M. H. Liu, C. Ye, X. Chen, Y. Y. Wang, K. He, L. L. Wang, X. C. Ma, Intrinsic topological insulator Bi2Te3 thin films on Si and their thickness limit. Advanced materials 22, 4002-4007 (2010).
21. Y. H. Lee, X. Q. Zhang, W. Zhang, M. T. Chang, C. T. Lin, K. D. Chang, Y. C. Yu, J. T. W. Wang, C. S. Chang, L. J. Li, Synthesis of Large‐Area MoS2 Atomic Layers with Chemical Vapor Deposition. Advanced Materials 24, 2320-2325 (2012).
22. Y. Zhan, Z. Liu, S. Najmaei, P. M. Ajayan, J. Lou, Large‐Area Vapor‐Phase Growth and Characterization of MoS2 Atomic Layers on a SiO2 Substrate. Small 8, 966-971 (2012).
23. K.-K. Liu, W. Zhang, Y.-H. Lee, Y.-C. Lin, M.-T. Chang, C.-Y. Su, C.-S. Chang, H. Li, Y. Shi, H. Zhang, Growth of large-area and highly crystalline MoS2 thin layers on insulating substrates. Nano letters 12, 1538-1544 (2012).
24. Y. Shi, W. Zhou, A.-Y. Lu, W. Fang, Y.-H. Lee, A. L. Hsu, S. M. Kim, K. K. Kim, H. Y. Yang, L.-J. Li, Van der Waals epitaxy of MoS2 layers using graphene as growth templates. Nano letters 12, 2784-2791 (2012).
25. H. Peng, S. Meister, C. K. Chan, X. F. Zhang, Y. Cui, Morphology control of layer-structured gallium selenide nanowires. Nano letters 7, 199-203 (2007).
26. D. Kong, W. Dang, J. J. Cha, H. Li, S. Meister, H. Peng, Z. Liu, Y. Cui, Few-layer nanoplates of Bi2Se3 and Bi2Te3 with highly tunable chemical potential. Nano letters 10, 2245-2250 (2010).
27. D. Kong, J. C. Randel, H. Peng, J. J. Cha, S. Meister, K. Lai, Y. Chen, Z.-X. Shen, H. C. Manoharan, Y. Cui, Topological insulator nanowires and nanoribbons. Nano letters 10, 329-333 (2009).
28. R. Tenne, L. Margulis, M. e. a. Genut, G. Hodes, Polyhedral and cylindrical structures of tungsten disulphide. Nature 360, 444-446 (1992).
29. Y. Feldman, E. Wasserman, D. Srolovitz, R. Tenne, High-rate, gas-phase growth of MoS2 nested inorganic fullerenes and nanotubes. Science 267, 222-225 (1995).
30. R. Tenne, Inorganic nanotubes and fullerene-like nanoparticles. Journal of materials research 21, 2726-2743 (2006).
31. B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, A. Kis, Single-layer MoS2 transistors. Nature nanotechnology 6, 147-150 (2011).
32. H. Fang, S. Chuang, T. C. Chang, K. Takei, T. Takahashi, A. Javey, High-performance single layered WSe2 p-FETs with chemically doped contacts. Nano letters 12, 3788-3792 (2012).
33. Q. H. Wang, K. Kalantar-Zadeh, A. Kis, J. N. Coleman, M. S. Strano, Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nature nanotechnology 7, 699-712 (2012).
34. M. Chhowalla, G. A. Amaratunga, Thin films of fullerene-like MoS2 nanoparticles with ultra-low friction and wear. Nature 407, 164-167 (2000).
35. X. Wang, X. Li, L. Zhang, Y. Yoon, P. K. Weber, H. Wang, J. Guo, H. Dai, N-doping of graphene through electrothermal reactions with ammonia. Science 324, 768-771 (2009).
36. R. Prins, V. De Beer, G. Somorjai, Structure and function of the catalyst and the promoter in Co—Mo hydrodesulfurization catalysts. Catalysis Reviews—Science and Engineering 31, 1-41 (1989).
37. M. Salmeron, G. Somorjai, A. Wold, R. Chianelli, K. Liang, The adsorption and binding of thiophene, butene and H2S on the basal plane of MoS2 single crystals. Chemical Physics Letters 90, 105-107 (1982).
38. B. Hinnemann, P. G. Moses, J. Bonde, K. P. Jørgensen, J. H. Nielsen, S. Horch, I. Chorkendorff, J. K. Nørskov, Biomimetic hydrogen evolution: MoS2 nanoparticles as catalyst for hydrogen evolution. Journal of the American Chemical Society 127, 5308-5309 (2005).
39. T. F. Jaramillo, K. P. Jørgensen, J. Bonde, J. H. Nielsen, S. Horch, I. Chorkendorff, Identification of active edge sites for electrochemical H2 evolution from MoS2 nanocatalysts. science 317, 100-102 (2007).
40. S. M. Ahmed, H. Gerischer, Influence of crystal surface orientation on redox reactions at semiconducting MoS2. Electrochimica Acta 24, 705-711 (1979).
41. Q. Zhu, S. L. Wegener, C. Xie, O. Uche, M. Neurock, T. J. Marks, Sulfur as a selective ‘soft’oxidant for catalytic methane conversion probed by experiment and theory. Nature chemistry 5, 104-109 (2013).
42. D. Kong, H. Wang, J. J. Cha, M. Pasta, K. J. Koski, J. Yao, Y. Cui, Synthesis of MoS2 and MoSe2 films with vertically aligned layers. Nano letters 13, 1341-1347 (2013).
43. E. M. Fernández, P. G. Moses, A. Toftelund, H. A. Hansen, J. I. Martínez, F. Abild‐Pedersen, J. Kleis, B. Hinnemann, J. Rossmeisl, T. Bligaard, Scaling relationships for adsorption energies on transition metal oxide, sulfide, and nitride surfaces. Angewandte Chemie International Edition 47, 4683-4686 (2008).
44. T. Onodera, Y. Morita, A. Suzuki, M. Koyama, H. Tsuboi, N. Hatakeyama, A. Endou, H. Takaba, M. Kubo, F. Dassenoy, A computational chemistry study on friction of h-MoS2. Part I. Mechanism of single sheet lubrication. The Journal of Physical Chemistry B 113, 16526-16536 (2009).
45. A. Vojvodic, B. Hinnemann, J. K. Nørskov, Magnetic edge states in MoS2 characterized using density-functional theory. Physical Review B 80, 125416 (2009).
46. J. N. Coleman, M. Lotya, A. O’Neill, S. D. Bergin, P. J. King, U. Khan, K. Young, A. Gaucher, S. De, R. J. Smith, Two-dimensional nanosheets produced by liquid exfoliation of layered materials. Science 331, 568-571 (2011).
47. M. De Barros Bouchet, J. Martin, T. Le Mogne, P. Bilas, B. Vacher, Y. Yamada, Mechanisms of MoS2 formation by MoDTC in presence of ZnDTP: effect of oxidative degradation. Wear 258, 1643-1650 (2005).
48. H. Ramakrishna Matte, A. Gomathi, A. K. Manna, D. J. Late, R. Datta, S. K. Pati, C. Rao, MoS2 and WS2 analogues of graphene. Angewandte Chemie 122, 4153-4156 (2010).
49. Z. Zeng, Z. Yin, X. Huang, H. Li, Q. He, G. Lu, F. Boey, H. Zhang, Single‐Layer Semiconducting Nanosheets: High‐Yield Preparation and Device Fabrication. Angewandte Chemie International Edition 50, 11093-11097 (2011).
50. C. Lee, H. Yan, L. E. Brus, T. F. Heinz, J. Hone, S. Ryu, Anomalous lattice vibrations of single-and few-layer MoS2. ACS nano 4, 2695-2700 (2010).
51. T. Korn, S. Heydrich, M. Hirmer, J. Schmutzler, C. Schüller, Low-temperature photocarrier dynamics in monolayer MoS2. Applied Physics Letters 99, 102109 (2011).
52. G. Eda, H. Yamaguchi, D. Voiry, T. Fujita, M. Chen, M. Chhowalla, Photoluminescence from chemically exfoliated MoS2. Nano letters 11, 5111-5116 (2011).
53. K. Novoselov, D. Jiang, F. Schedin, T. Booth, V. Khotkevich, S. Morozov, A. Geim, Two-dimensional atomic crystals. Proceedings of the National Academy of Sciences of the United States of America 102, 10451-10453 (2005).
54. K. Lee, H. Y. Kim, M. Lotya, J. N. Coleman, G. T. Kim, G. S. Duesberg, Electrical characteristics of molybdenum disulfide flakes produced by liquid exfoliation. Advanced Materials 23, 4178-4182 (2011).
55. B. Radisavljevic, M. B. Whitwick, A. Kis, Integrated circuits and logic operations based on single-layer MoS2. Acs Nano 5, 9934-9938 (2011).
56. J. Xiao, D. Choi, L. Cosimbescu, P. Koech, J. Liu, J. P. Lemmon, Exfoliated MoS2 nanocomposite as an anode material for lithium ion batteries. Chemistry of Materials 22, 4522-4524 (2010).
57. H. Li, Z. Yin, Q. He, H. Li, X. Huang, G. Lu, D. W. H. Fam, A. I. Y. Tok, Q. Zhang, H. Zhang, Fabrication of Single‐and Multilayer MoS2 Film‐Based Field‐Effect Transistors for Sensing NO at Room Temperature. Small 8, 63-67 (2012).
58. Z. Yin, H. Li, H. Li, L. Jiang, Y. Shi, Y. Sun, G. Lu, Q. Zhang, X. Chen, H. Zhang, Single-layer MoS2 phototransistors. ACS nano 6, 74-80 (2011).
59. W. Zhou, Z. Yin, Y. Du, X. Huang, Z. Zeng, Z. Fan, H. Liu, J. Wang, H. Zhang, Synthesis of Few‐Layer MoS2 Nanosheet‐Coated TiO2 Nanobelt Heterostructures for Enhanced Photocatalytic Activities. small 9, 140-147 (2013).
60. K. F. Mak, C. Lee, J. Hone, J. Shan, T. F. Heinz, Atomically thin MoS2: a new direct-gap semiconductor. Physical Review Letters 105, 136805 (2010).
61. A. Splendiani, L. Sun, Y. Zhang, T. Li, J. Kim, C.-Y. Chim, G. Galli, F. Wang, Emerging photoluminescence in monolayer MoS2. Nano letters 10, 1271-1275 (2010).
62. K. P. Loh, Q. Bao, G. Eda, M. Chhowalla, Graphene oxide as a chemically tunable platform for optical applications. Nature chemistry 2, 1015-1024 (2010).
63. R. Gordon, D. Yang, E. Crozier, D. Jiang, R. Frindt, Structures of exfoliated single layers of WS2, MoS2, and MoSe2 in aqueous suspension. Physical Review B 65, 125407 (2002).
64. B. Sipos, A. F. Kusmartseva, A. Akrap, H. Berger, L. Forró, E. Tutiš, From Mott state to superconductivity in 1T-TaS2. Nature materials 7, 960-965 (2008).
65. A. Kuc, N. Zibouche, T. Heine, Influence of quantum confinement on the electronic structure of the transition metal sulfide TS2. Physical Review B 83, 245213 (2011).
66. T. Cao, G. Wang, W. Han, H. Ye, C. Zhu, J. Shi, Q. Niu, P. Tan, E. Wang, B. Liu, Valley-selective circular dichroism of monolayer molybdenum disulphide. Nature communications 3, 887 (2012).
67. H. Zeng, J. Dai, W. Yao, D. Xiao, X. Cui, Valley polarization in MoS2 monolayers by optical pumping. Nature nanotechnology 7, 490-493 (2012).
68. K. F. Mak, K. He, J. Shan, T. F. Heinz, Control of valley polarization in monolayer MoS2 by optical helicity. Nature nanotechnology 7, 494-498 (2012).
69. J. A. Wilson, F. Di Salvo, S. Mahajan, Charge-density waves and superlattices in the metallic layered transition metal dichalcogenides. Advances in Physics 24, 117-201 (1975).
70. J. Wilson, A. Yoffe, The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties. Advances in Physics 18, 193-335 (1969).
71. M. Chhowalla, H. S. Shin, G. Eda, L.-J. Li, K. P. Loh, H. Zhang, The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nature chemistry 5, 263-275 (2013).
72. A. J. Bard, L. R. Faulkner, ELECTROCHEMICAL METHODS : Fundamentals and Applications. (ed. second edition).
73. Y. Yan, X. Ge, Z. Liu, J.-Y. Wang, J.-M. Lee, X. Wang, Facile synthesis of low crystalline MoS2 nanosheet-coated CNTs for enhanced hydrogen evolution reaction. Nanoscale 5, 7768-7771 (2013).
74. N. Pentland, J. M. Bockris, E. Sheldon, Hydrogen Evolution Reaction on Copper, Gold, Molybdenum, Palladium, Rhodium, and Iron Mechanism and Measurement Technique under High Purity Conditions. Journal of The Electrochemical Society 104, 182-194 (1957).
75. B. Conway, B. Tilak, Interfacial processes involving electrocatalytic evolution and oxidation of H2, and the role of chemisorbed H. Electrochimica Acta 47, 3571-3594 (2002).
76. Z. Chen, D. Cummins, B. N. Reinecke, E. Clark, M. K. Sunkara, T. F. Jaramillo, Core–shell MoO3–MoS2 nanowires for hydrogen evolution: A functional design for electrocatalytic materials. Nano letters 11, 4168-4175 (2011).
77. D. Merki, S. Fierro, H. Vrubel, X. Hu, Amorphous molybdenum sulfide films as catalysts for electrochemical hydrogen production in water. Chemical Science 2, 1262-1267 (2011).
78. J. D. Benck, Z. Chen, L. Y. Kuritzky, A. J. Forman, T. F. Jaramillo, Amorphous molybdenum sulfide catalysts for electrochemical hydrogen production: insights into the origin of their catalytic activity. Acs Catalysis 2, 1916-1923 (2012).
79. Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong, H. Dai, MoS2 nanoparticles grown on graphene: an advanced catalyst for the hydrogen evolution reaction. Journal of the American Chemical Society 133, 7296-7299 (2011).
80. Q. Xiang, J. Yu, M. Jaroniec, Synergetic effect of MoS2 and graphene as cocatalysts for enhanced photocatalytic H2 production activity of TiO2 nanoparticles. Journal of the American Chemical Society 134, 6575-6578 (2012).
81. E. G. Firmiano, M. A. Cordeiro, A. C. Rabelo, C. J. Dalmaschio, A. N. Pinheiro, E. C. Pereira, E. R. Leite, Graphene oxide as a highly selective substrate to synthesize a layered MoS2 hybrid electrocatalyst. Chemical Communications 48, 7687-7689 (2012).
82. L. Liao, J. Zhu, X. Bian, L. Zhu, M. D. Scanlon, H. H. Girault, B. Liu, MoS2 Formed on Mesoporous Graphene as a Highly Active Catalyst for Hydrogen Evolution. Advanced Functional Materials 23, 5326-5333 (2013).
83. 汪建民主編, 材料分析, 中國材料科學學會.
84. www.purdue.edu/ehps/rem/rs/sem.htm, 掃描式電子顯微鏡
85. 江昆鏗, 燃料輔助法製備氧化鎳薄膜及其在電致變色元件與電阻式隨機存取記憶體之應用. 成功大學化工系碩士論文, (民國100年).
86. www.aandb.com.tw/Page0004/uv_vis_04_lambda_850.htm, 紫外光/可見光分光光譜儀產品介紹, 博精儀器股份有限公司.
87. H. Li, Q. Zhang, C. C. R. Yap, B. K. Tay, T. H. T. Edwin, A. Olivier, D. Baillargeat, From bulk to monolayer MoS2: evolution of Raman scattering. Advanced Functional Materials 22, 1385-1390 (2012).
88. A. Ferrari, J. Robertson, Resonant Raman spectroscopy of disordered, amorphous, and diamondlike carbon. Physical Review B 64, 075414 (2001).
89. 蔡淑惠, 拉曼光譜在奈米碳管檢測上之應用. 奈米通訊 第十二期, p49.
90. C. Ho, I. Raistrick, R. Huggins, Application of A‐C Techniques to the Study of Lithium Diffusion in Tungsten Trioxide Thin Films. Journal of The Electrochemical Society 127, 343-350 (1980).
91. 溫景發, 田大昌, 羅聖全, 黃宏盛, 鄭信民, 林明為, 胡堂祥, 何家充, 有機薄膜電晶體微結構分析技術開發. 電子與材料雜誌 第27期, 28-36.
92. Y. Yu, S.-Y. Huang, Y. Li, S. N. Steinmann, W. Yang, L. Cao, Layer-Dependent Electrocatalysis of MoS2 for Hydrogen Evolution. Nano letters 14, 553-558 (2014).
93. T. L. Barr, An ESCA study of the termination of the passivation of elemental metals. The Journal of Physical Chemistry 82, 1801-1810 (1978).
94. H. Vrubel, D. Merki, X. Hu, Hydrogen evolution catalyzed by MoS3 and MoS2 particles. Energy & Environmental Science 5, 6136-6144 (2012).
95. T. Weber, J. Muijsers, J. Niemantsverdriet, Structure of amorphous MoS3. The Journal of Physical Chemistry 99, 9194-9200 (1995).