本研究主要探討錳-鐵二元氧化物的電極製備技術與各種材料特性，並進一步瞭解其擬電容行為。在電極製程中，於0.25 M的醋酸錳水溶液中分別添加濃度0-0.15 M氯化鐵作為鍍液，利用陽極沉積法可將錳-鐵二元氧化物析鍍於石墨基材上。所得之氧化物以X光能量散佈分析儀(EDS)偵測其化學成份、以X光繞射分析儀(XRD)分析其結晶性，以SEM觀察其表面形貌。並以XPS及XANES（X-ray absorption near edge structure）進行其化學化合狀態的分析。在電化學分析方面，以循環伏安法(CV)量測氧化物電極之擬電容特性。實驗結果顯示，氧化物中鐵含量與鍍液中氯化鐵的添加濃度成線性正比關係。另外，雖然添加鐵並沒有改變錳氧化物原本的非晶質結構，但卻會對其表面細微形貌產生重要的影響。另一方面，添加0.05 M氯化鐵為鍍液者之錳鐵氧化物能得到最高的電極表面粗糙度及最高擬電容值。氧化物電極的循環充放電穩定性也會由於鐵的添加而被明顯提昇。
Mn-Fe二元氧化物經熱處理溫度100℃時，此時擁有較佳的電容值，約280 F/g，掃瞄速率 = 5 mV/sec。且氧化物經熱處後，其電化學穩定性皆大幅提昇。而當熱處理溫度提升至500℃以上時，錳-鐵二元氧化物發生結晶化反應形成(Mn-Fe)2O3結晶相。而此結晶性(Mn-Fe)2O3相出現會造成電解液中的質子或其他的陽離子進出氧化物的反應受到阻礙，使氧化物電極完全喪失其原有的擬電容特性。
本研究進一步利用in situ X光吸收光譜技術探討錳-鐵二元氧化物在充放電的過程中儲存電荷的反應機制。在in situ實驗中，發現當外加電位增加時Mn及Fe的吸收峰會往高能量偏移，代表錳及鐵的氧化價數往高價移動；而當外加電位降低時，Mn 及Fe K-edge的吸收峰會往低能量偏移(即氧化價數降低)，。此XAS的結果直接證明在充放電的過程中，錳及鐵的氧化物是有直接參與法拉第電荷轉移。
本研究亦探討錳鐵二元氧化物於KCl水溶液中，錳及鐵的氧化價數在外加電位範圍內(0–1VSCE)的臨場變化，與電容值做進一步比較。利用in situ X光吸收光譜分析結果顯示鐵的增加可提高錳的價數變化量，因此在適當Fe/Mn比例的條件下錳鐵二元氧化物電極的電容值會高於單純氧化錳電極。然而當鐵的比例持續增加時，其電容值反而有下降的情形發生，其原因在於鐵的氧化價數變化量僅為0.55(低於錳的0.80)。當鐵的含量比例持續增加時，氧化物中整體陽離子的平均價數變化量會逐漸減少，因而導致氧化物電極的擬電容值降低。
本研究中亦成功證實氧化錳也可以在離子液體中具有擬電容行為，且在無質子的離子液體中(例如：EMI-DCA或是BMP-DCA)亦顯示出良好的擬電容效應。此外，本研究也針對氧化錳在離子液體間的儲能機制進行探討，發現其擬電容現象主要是離子液體中陰離子（DCA-）在充放電的過程中嵌入(Insertion)/脫離(desertion)二個相鄰的MnO6八面體晶胞結構所導致，亦即離子液體中陰離子（DCA-）與電極表面的氧化錳交互作用所貢獻的。而陽離子(EMI+及BMP+)則僅僅吸附在電極表面，並不直接參與反應。

Effects of iron additions on the material and electrochemical properties of manganese oxides were investigated in this study. The Mn-Fe binary oxide electrodes were prepared by anodic deposition on graphite substrates. The deposition solution was a mixture of FeCl3 with manganese acetate aqueous electrolyte. It was found that Fe content in the binary oxide can be easily controlled by adjusting the composition of the plating solution. Crystal structure and surface morphology of the deposited oxides were examined by XRD and SEM, while their chemical state was analyzed by X-ray photoelectron spectroscopy and X-ray absorption near edge structure. Pseudo-capacitive performance of various oxide electrodes were determined by cyclic voltammetry (CV) in 2M KCl aqueous solution. SEM observation clearly showed that Fe dopings caused changes of surface morphology of the oxide electrodes. The data indicated that the doped Fe in proper concentration significantly increased specific capacitance of the oxide electrode. On the other hand, cyclic charge/discharge stability of the manganese oxide electrode was improved obviously by adding Fe.
Tailoring the material characteristics and thus the electrochemical performance of the oxide was attempted by annealing (up to 700ºC in air). The 100ºC-annealed oxide, evaluated by cyclic voltammetry at a potential sweep rate of 5 mVs-1, showed an optimum specific capacitance of 280 Fg-1. Cyclic stability of the oxide electrode can also be improved by post-heat treatment. However, the binary oxide loses its pseudocapacitive capability at the annealing temperature of 500ºC, at which point the formation of crystalline (Mn–Fe)2O3 occurs.
In order to explore the electron storage mechanism, the deposited oxides were studied by in situ X-ray absorption spectroscopy (XAS) in 2 M KCl solution during the charging–discharging process. The experimental results clearly confirmed that the oxidation states of both Mn and Fe changed forth and back with adjusting the applied potential, contributing to the pseudocapacitive characteristics of the binary oxides. It was also found that, within a potential range of 1 V, Fe oxide addition would increase the variation in Mn oxidation state from 0.70 to 0.81, while Fe oxide itself demonstrated an oxidation state shift of only 0.55. Accordingly, an optimum pseudocapacitance of the binary Mn–Fe oxide could be only achieved as the amount of Fe oxide was properly controlled.
Developing Mn oxide supercapacitors incorporating protic and aprotic ionic liquid (IL) electrolytes was attempted. The experimental results indicate a possibility of achieving pseudocapacitive performance without involving protons and alkali cations, and thus open a new route of developing novel electrolytes for various metal oxide based pseudocapacitors. Significant enhancement in the electrochemical stability of Mn oxide was confirmed in EMI-DCA or BMP-DCA IL, when compared to aqueous electrolytes. Moreover, the analytical results indicate that Mn3+/Mn4+ redox transition during the charge-discharge process was charge compensated by the reversible insertion/desertion reaction of DCA- anion into/from the tunnels between the MnO6 octahedral units. The EMI+ or BMP+ cations were just adsorbed on the electrode surface and did not penetrate into the oxide.

參考文獻
[1] R. Kötz, M. Carlen, “Principles and applications of electrochemical capacitors”, Electrochim. Acta, 45 (2000) 2483-2498.
[2] E. Conway, Electrochemical Super Capacitors, Kluwer-Plenum, New York (1999).
[3] A. Burke, “Ultracapacitors : why, how, and where is the technology”, J. Power Sources, 91 (2000) 37-50.
[4] B. E. Conway, “Transition from “supercapacitor” to “battery” behavior in electrochemical energy storage”, J. Electrochem. Soc., 138 (1991) 1539-1548.
[5] I. D. Raistrick, Electrochemistry in Electronics, Noyes Publications, Park Ridge, NJ (1995).
[6] S. Trasatti, P. Kurzweil, “Electrochemical Supercapacitors as Versatile Energy Stores”, Platin. Met. Rev., 38 (1994) 46-56.
[7] B. E. Conway, V. Birss, J. Wojtowicz, “The role and utilization of pseudocapacitance for energy storage by supercapacitors”, J. Power Sources, 66(1997) 1-14
[8] S. Sarangapani, B. V. Tilak, C. P. Chen, “Materials for electrochemical capacitors”, J. Electrochem. Soc., 143 (1996) 3791-3799.
[9] G. L. Bullard, H. B. Sierra-Alcazar, H. L. Lee, J. L. Morris, ”Operating principles of the ultracapacitor”, IEEE Trans. Magnet., 25 (1989) 102-106.
[10] J. P. Zheng, J. Huang, T. R. Jow, “The limitations of energy density for electrochemical capacitors”, J. Electrochem. Soc., 144 (1997) 2026-2031.
[11] E. Faggioli, P. Rena, V. Danel, X. Andrieu, R. Mallant, H. Kahlen, “Supercapacitors for the energy management of electric vehicles”, J. Power Sources, 84 (1999) 261-269.
[12] R. A. Huggins, “Supercapacitors and electrochemical pulse sources”, Solid State Ionics, 134 (2000) 179-195.
[13] M. Ishikawa, M. Morita, M. Ihara, Y. Matsuda, “Electric double-layer capacitor composed of activated carbon-fiber cloth electrodes and solid polymer electrolytes containing alkylammonium salts”, J. Electrochem. Soc., 141 (1994) 1730-1734.
[14] B. Pillay, J. Newman, “The influence of side reactions on the performance of electrochemical double-layer capacitors”, J. Electrochem. Soc., 143 (1996) 1806-1814.
[15] S. Sarangapani, P. Lessner, J. Forchione, A. Griffith, A. B. Laconti, “Advanced double-layer capacitors”, J. Power Sources, 29 (1990) 355-364.
[16] T. Morimoto, K. Hiratsuka, Y. Sanada, K. Kurihara, “Electric double-layer capacitor using organic electrolyte”, J. Power Sources, 60 (1996) 239-247.
[17] D. Qu, H. Shi, “Studies of activated carbons used in double-layer capacitors”, J. Power Sources, 74 (1998) 99-107.
[18] I. Tanahashi, A. Yoshida, A. Nishino, “Preparation and characterization of activated carbon tablets for electric double-layer capacitors”, Bull. Chem. Soc. Jpn., 63 (1990) 2755-2758.
[19] T. C. Weng, H. Teng, “Characterization of High Porosity Carbon Electrodes Derived from Mesophase Pitch for Electric Double-Layer Capacitors”, J. Electrochem. Soc., 148(2001) A368-A373.
[20] J. P. Zheng, T. R. Jow, “A new charge storage mechanism for electrochemical capacitors”, J. Electrochem. Soc., 142 (1995) L6-L8.
[21] J. P. Zheng, P. J. Cygan, T. R. Jow, “Hydrous ruthenium oxide as an electrode material for electrochemical capacitors”, J. Electrochem. Soc., 142 (1995) 2699-2703.
[22] Y. Takasu, T. Nakamura, H. Ohkawauchi, Y. Murakami, “Dip-coated Ru-V oxide electrodes for electrochemical capacitors”, J. Electrochem. Soc., 144 (1997) 2601-2606.
[23] K. Rajendra Prasad, N. Munichandraiah, “Potentiodynamically deposited polyaniline on stainless steel – Inexpensive, high-performance electrodes for electrochemical capacitors”, J. Electrochem. Soc., 149 (2002) A1393-A1399.
[24] M. Mastragostino, C. Arbizzani, F. Soavi, “Polymer-based supercapacitors”, J. Power Sources, 97-98 (2001) 812-815.
[25] C. Arbizzani, M. Mastragostino, F. Soavi, “New trends in electrochemical supercapacitors” , J. Power Sources, 100 (2001) 164-170.
[26] C. C. Hu, W. C. Chen, K. H. Chang, “How to achieve maximum utilization of hydrous ruthenium oxide for supercapacitors”, J. Electrochem. Soc., 151 (2004) A281-A290.
[27] C. C. Hu, W. C. Chen, “Effects of substrates on the capacitive performance of RuOx••nH2O and activated carbon–RuOx electrodes for supercapacitors”, Electrochim. Acta, 49(2004) 3469-3477.
[28] T. C. Wen, C. C. Hu, “Hydrogen and oxygen evolutions on Ru-Ir binary oxide”, J. Electrochem. Soc., 139(1992) 2158-2163.
[29] L. Nanni, S. Polizzi, A. Benedetti, A. D. Battisti, “Morphology, Microstructure, and Electrocatalytic properties of RuO2-SnO2 thin films”, J. Electrochem. Soc., 146(1999) 220-225.
[30] M. Ito, Y. Murakami, H. Kaji, K. Yahikozawal, Y. Takasu, “Surface Characterization of RuO2-SnO2 coated titanium electrodes” J. Electrochem. Soc., 143(1996) 32-36.
[31] N. L.Wu, S. Y. Wang, C. Y. Han, D. S. Wu, L. R. Shiue, “Electrochemical capacitor of magnetite in aqueous electrolytes”, J. Power Sources, 113(2003) 173-178.
[32] S. Y. Wang, K. C. Ho, S. L. Kuo, N. L. Wu, “Investigation on Capacitance Mechanisms of Fe3O4 Electrochemical Capacitors”, J. Electrochem. Soc., 153(2006) A75-A80.
[33] S. Y. Wang, N. L. Wu, “Operating characteristics of aqueous magnetite electrochemical capacitors”, J. Appl. Electrochem., 33(2003)345-348.
[34] N. Nagarajan, I. Zhitomirsky, “Cathodic electrosynthesis of iron oxide films for electrochemical supercapacitors”, J. Appl. Electrochem., 36(2006) 1399-1405.
[35] P. Simon, Y. Gogotsi, “Materials for electrochemical capacitors”, Nature Materials, 7(2008) 845-854.
[36] K. Naoi and P. Simon, J. Electrochem. Soc. Interface 17(2008) 34-37
[37] D. R. Craig, Can. Pat., 1,196,683 (1985).
[38] S. Hadzi-Jordanov, H. Angerstein-Kozlowska, M. Vukovic, B. E. Conway, “Reversibility and growth behavior of surface oxide films at ruthenium electrodes”, J. Electrochem. Soc., 125 (1978) 1471-1480.
[39] D. Galizzioli, F. Tantardini, S. Trasatti, “A new electrode material eem dash I. Behaviour in acid solutions of inert electrolytes”, J. Appl. Electrochem., 4 (1974) 57-67.
[40] T. Liu, W. G. Pell, B. E. Conway, “Self-discharge and potential recovery phenomena at thermally and electrochemically prepared RuO2 supercapacitor electrodes”, Electrochim. Acta, 42 (1997) 3541-3552.
[41] I. H. Kim, K. B. Kim, “Ruthenium oxide thin film electrodes prepared by electrodes spray deposition and their charge storage mechanism”, J. Electrochem. Soc., 151 (2004) E7-E13.
[42] I. D. Raistrick, in The Electrochemistry of Semiconductors and Electronics-Processes and Device, p. 297, J. McHardy, F. Luduig, Editors, Noyes, Park Ridge, NJ (1992).
[43] Q. L. Fang, D. A. Evans, S. L. Roberson, J. P. Zheng, “Ruthenium oxide film electrodes prepared at low temperatures for electrochemical capacitors”, J. Electrochem. Soc., 148 (2001) A833-A837.
[44] J. P. Zheng, T. R. Jow, “High energy and high power density electrochemical capacitors”, J. Power Sources, 62 (1996) 155-159.
[45] R. Fu, Z. Ma, J. P. Zheng, “Proton NMR and dynamic studies of hydrous ruthenium oxide”, J. Phys. Chem. B, 106 (2002) 3592-3596.
[46] J. P. Zheng, “Ruthenium oxide-carbon composite electrodes for electrochemical capacitors”, Electrochem. Solid-State Lett., 2(1999) 359-361.
[47] J. Zhang, D. Jiang, B. Chen, J. Zhu, L. Jiang, and H. Fan, “Preparation and electrochemistry of hydrous ruthenium oxide/active carbon electrode materials for supercapacitor”, J. Electrochem. Soc., 148(2001) A1362-A1367.
[48] M. Ramani, B. S. Haran, R. E. White, B. N. Popov, and L. Arsov, “Studies on activated carbon capacitor materials loaded with different amounts of ruthenium oxide”, J. Power Sources, 93(2001) 209-214.
[49] H. Kim, B. N. Popov, “Characterization of hydrous ruthenium oxide/carbon nanocomposite supercapacitors prepared by a colloidal method”, J. Power Sources, 104(2002) 52-61.
[50] J. H. Park, J. M. Ko, and O. O. Park, “Carbon Nanotube/RuO2 Nanocomposite Electrodes for Supercapacitors”, J. Electrochem. Soc., 150(2003) A864-A867.
[51] H. Y. Lee, J. B. Goodenough, “Supercapacitor behavior with KCl electrolyte”, J. Solid State Chem., 144 (1999) 220-223.
[52] C. C. Hu, T. W. Tsou, “Idea capacitive behavior of hydrous manganese oxide prepared by anodic deposition”, Electrochem. Commun., 4 (2002) 105-109.
[53] J. K. Chang, W. T. Tsai, “Material characterization and electrochemical performance of hydrous manganese oxide electrodes for use in electrochemical pseudocapacitors”, J. Electrochem. Soc., 150 (2003) A1333-A1338.
[54] N. Nagarajan, H. Humadi, I. Zhitomirsky, “Cathodic electrodeposition of MnOx films for electrochemical supercapacitors”, Electrochim. Acta, 51 (2006) 3039-3045.
[55] J. K. Chang, C. H. Huang, W. T. Tsai, M. J. Deng, I. W. Sun, “Ideal pseudocapacitive performance of the Mn oxide anodized from the nanostructured and amorphous Mn thin film electrodeposited in BMP–NTf2 ionic liquid ”, J. Power Sources, 179 (2008) 435-440.
[56] H .Y. Lee, V. Manivannan, J. B. Goodenough, “Electrochemical capacitors with KCl electrolyte”, Comptes Rendus Chimie, 2 (1999) 565-573.
[57] M. Toupin, T. Brousse, D. Bélanger, “Influence of microstructure on the charge storage properties of chemically synthesized manganese dioxide”, Chem. Mater., 14 (2002) 3946-3952.
[58] H. Kim, B.N. Popov, “Synthesis and characterization of Mno2-base mixed oxides as supercapacitors”, J. Electrochem. Soc., 150 (2003) D56-D62.
[59] M. Toupin, T. Brousse, D. Bélanger, “Charge storage mechanism of MnO2 electrode used in aquesous electrochemical capacitor”, Chem. Mater., 16 (2004) 3184-3190.
[60] S. C. Pang, M. A. Anderson, T. W. Chapman, “Novel electrode materials for thin-film ultracapacitors : Comparison of electrochemical properties of sol-gel derived and electrodepositied manganese dioxide”, J. Electrochem. Soc., 147 (2000) 444-450.
[61] S. C. Pang, M. A. Anderson, “Novel electrode materials for electrochemical capacitors : Part II. Material characterization of sol-gel-derived and electrodeposition manganese dioxide thin films”, J. Mater. Res., 15 (2000) 2096-2106.
[62] Y. U. Jeong, A. Manthiram, “Nanocrystalline manganese oxides for electrochemical capacitors with neutral electrolytes”, J. Electrochem. Soc., 149 (2002) A1419-1422.
[63] R. N. Reddy, R. G. Reddy, “Sol-gel MnO2 as an electrode material for electrochemical capacitors”, J. Power Sources, 124 (2003) 330-337.
[64] J. N. Broughton, M. J. Brett, “Electrochemical capacitance in manganese thin films with chevron microstructure”, Electrochem. Solid-State Lett., 5 (2002) A279-A282.
[65] B. Djurfors, J. N. Broughton, M. J. Brett, D. G. Ivey, “Microstructural characterization of porous manganese thin films for electrochemical supercapacitor applications”, J. Mater. Sci., 38 (2003) 4817-4830.
[66] V. Subramanian, H. Zhu, R. Vajtai, P.M. Ajayan, B. Wei, “Hydrothermal Synthesis and Pseudocapacitance Properties of MnO2 Nanostructures”, J. Phys. Chem. B, 109 (2005) 20207-20214.
[67] C. C. Hu, Y. T. Wu, K. H. Chang, “Low-Temperature Hydrothermal Synthesis of Mn3O4 and MnOOH Single Crystals: Determinant Influence of Oxidants”, Chem. Mater., 20 (2008) 2890-2894.
[68] S. Wen, J. W. Lee, I. H. Yeo, J. Park, S. I. Mho, “The role of cations of the electrolyte for the pseudocapacitive behavior of metal oxide electodes, MnO2 and RuO2”, Electrochim. Acta, 50 (2004) 849-855.
[69] O. Ghodbane, J. L. Pascal, F. Favier, “Microstructural Effects on Charge-Storage Properties in MnO2-Based Electrochemical Supercapacitors”, ACS Appl. Mater. Interfaces 1(2009) 1130-1139
[70] S. Devaraj, N. Munichandraiah, “EQCM Investigation of the Electrodeposition of MnO2 and Its Capacitance Behavior”, Electrochemical and Solid-State Letters, 12(2009) F21-F25
[71] S. L. Kuo, N. L. Wu, “Electrochemical Capacitor of MnFe2O4 with NaCl Electrolyte”, Electrochemical and Solid-State Letters, 8 (2005) A495-A499.
[72] S. L. Kuo, N. L. Wu, “Electrochemical Capacitor of MnFe2O4 with Organic Li-Ion Electrolyte”, Electrochemical and Solid-State Letters, 10 (2007) A171-A175.
[73] S. L. Kuo., N. L. Wu, “Electrochemical characterization on MnFe2O4/carbon black composite aqueous supercapacitors” J. Power Sources, 162 (2006) 1437-1443.
[74] S. L. Kuo, J. F. Lee, N. L. Wu, “Study on Pseudocapacitance Mechanism of Aqueous MnFe2O4 Supercapacitor”, J. Electrochem. Soc., 154 (2007) A34-A38.
[75] R. N. Reddy, R. G. Reddy, “MnO2 as electrode material for electrochemical capacitors”, Electrochemical Society Proceeding, PV 2002-7 (2002) 197.
[76] H. Y. Lee, S. W. Kim, H. Y. Lee, “Expansion of active site area and improvement of kinetic reversibility in electrochemical pseudocapacitor electrode”, Electrochem. Solid State Letters, 4 (2001) A19-A22.
[77] R. N. Reddy, R. G. Reddy, “Synthesis and electrochemical characterization of amorphous MnO2 electrochemical capacitor electrode material”, J. Power Sources, 132 (2004) 315-320.
[78] S. F. Chin, S. C. Pang, M. A. Anderson, “Material and electrochemical characterization of tetrapropylammonium manganese oxide thin films as novel electrode materials for electrochemical capacitors”, J. Electrochem. Soc., 149 (2002) A379-A384.
[79] J. N. Broughton, M. J. Brett, “Electrochemical capacitance in manganese thin films with chevron microstructure”, Electrochim. Acta, 49 (2004) 4439-4446.
[80] K. R. Prasad, N. Miura, “Electrochemically synthesized MnO2-based mixed oxide for high performance redox supercapacitors”, Electrochem. Comm., 6 (2004) 1004-1008.
[81] K. R. Prasad, N. Miura, “Potentiodynamically deposited nanostructured manganese dioxide as electrode material for electrochemical redox supercapacitors”, J. Power Sources, 135 (2004) 354-360.
[82] A. Lewandowski, M. Galin´ski, “Carbon–ionic liquid double-layer capacitors”, J. Physics & Chemistry of Solids 65 (2004) 281-286.
[83] Y. Nagao, Y. Nakayama, H. Odab, M. Ishikawa “Activation of an ionic liquid electrolyte for electric double layer capacitors by addition of BaTiO3 to carbon electrodes”, J. Power Sources, 166(2007) 595-598.
[84] M. Lazzari, M. Mastragostino, F. Soavi, “Capacitance response of carbons in solvent-free ionic liquid electrolytes” Electrochem. Comm. 9(2007) 1567-1572.
[85] D. Rochefort, A. L. Pont, “Pseudocapacitive behaviour of RuO2 in a proton exchange ionic liquid”, Electrochem. Commun., 8(2006) 1539-1543.
[86] K. R. Seddon, A. Stark, M. J. Torres, “Influence of chloride, water, and organic solvents on the physical properties of ionic liquids”, Pure Appl. Chem., 72(2000) 2275-2287.
[87] J. D. Holbery, K. R. Seddon, “Ionic liquids”,Clean Technol. Environ. Pol., (1999)223-236
[88] (a)P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg), (1914)1800;
(b)S. Sugden and H. Wilkins, “CLXVII.—The parachor and chemical constitution. Part XII. Fused metals and salts”, J. Chem. Soc.(1929)1291-1298.
[89] F. H. Hurley, T. P. Wier, “Electrodeposition of Metals from Fused Quaternary Ammonium Salts”, J. Electrochem. Soc., 98(1951)203-206.
[90] H. L. Chum, V. R. Koch, L. L. Miller, R. A. Osteryong, “Electrochemical scrutiny of organometallic iron complexes and hexamethylbenzene in a room temperature molten salt”, J. Am. Chem. Soc., 97( 1975) 3264-3265.
[91] J. S. Wilkes, M.J. Zaworotko, “Air and water stable 1-ethyl-3-methylimidazolium based ionic liquids”, J. Chem. Soc., Chem. Commun., (1992)965-967.
[92] J. H. Davis, P. A. Fox., “From curiosities to commodities: ionic liquids begin the transition”, Chem. Commun., (2003)1209-1212.
[93] A. M. Leone, S. C. Weatherly, M. E. Williams, H. H. Thorp, R. W. Murray, “An Ionic Liquid Form of DNA: Redox-Active Molten Salts of Nucleic Acids”, J. Am. Chem. Soc., 123(2001)218-222.
[94] M. Yoshizawa, A. Narita, H. Ohno, “Design of Ionic Liquids for Electrochemical Applications”, Aust. J. Chem., 57(2004)139-144.
[95] S. Hayashi, H. Hamaguchi, “Discovery of a Magnetic Ionic Liquid [bmim]FeCl4”, Chem. Lett., 33(2004)1590-1591.
[96] K. Fukumoto, M. Yoshizawa, H. Ohno, “Room Temperature Ionic Liquids from 20 Natural Amino Acids”, J. Am. Chem. Soc., 127(2005) 2398-2399.
[97] A. J. Bard, L. R. Faulkner, Electrochemical Method-Fundamentals and Applications, John Wiley & Sons, New York (1980)
[98] M. Pourbaix, Atlas of Electrochemical Equilibria in Aqueous Solutions, National Association of Corrosion Engineers, Houston, Texas, USA (1966).
[99] B. R. Strohmeier, D. M. Hercules, “ Surface spectroscopic characterization of manganese/aluminum oxide catalysts”, J. Phys. Chem., 88 (1984) 4922-4929.
[100] B. N. Ivanov-Emin, N. A. Nevskaya, B. E. Zaitsev, T. M. Ivanova, Zh. Neorg. Khim., 27 (1982) 3101-3104.
[101] P. Ghigna, G. Flor and G. Spinolo, “An Mn–K Edge XAS Investigation on the Crystal Chemistry of Cd1−δMn2Oy”, J. Solid State Chem., 149(2000) 252-255.
[102] S. Quartieri, M. P. Riccardi, B. Messiga and F. Boscherini, “The ancient glass production of the Medieval Val Gargassa glasshouse: Fe and Mn XANES study”, J. Non-Cryst. Solids, 351(2005) 3013-3022.
[103] N. S. McIntyre and D. G. Zetaruk, “X-ray photoelectron spectroscopic studies of iron oxides”, Anal. Chem., 49(1977) 1521-1529.
[104] T. C. Lin, G. Seshadri and J. A. Kelber, “A consistent method for quantitative XPS peak analysis of thin oxide films on clean polycrystalline iron surfaces”, Appl. Surf. Sci., 119 (1997) 83-92.
[105] E. Preisler, “Semiconductor properties of manganese dioxide”, J. Appl. Electrochem., 6 (1976) 311-320.
[106] C. Tsang, J. Kim, A. Manthiram, “Synthesis of manganese oxides by reduction of KMnO4 with KBH4 in aqueous solutions”, J. Solid State Chem., 137 (1998) 28-32.
[107] H. Ikeda, U.S. Patent, 4,133,856.
[108] M. Chigane, M. Ishikawa, “Manganese oxide thin film preparation by potentiostatic electrolyses and electrochromism”, J. Electrochem. Soc., 147(2000) 2246-2251.
[109] M. Chigane, M. Ishikawa, M. Izaki, “Preparation of manganese oxide thin films by electrolysis/chemical deposition and electrochromism”, J. Electrochem. Soc., 148 (2001) D96-D101.
[110] M. T. Lee, J. K. Chang, W. T. Tsai, C. K. Lin, “ In situ X-ray absorption spectroscopic studies of anodically deposited binary Mn–Fe mixed oxides with relevance to pseudocapacitance” J. Power Sources,178(2008) 476-482.
[111] M. T. Lee, J. K. Chang, W. T. Tsai, “Effects of Iron Addition on Material Characteristics and Pseudo-Capacitive Behavior of Manganese Oxide Electrodes”, J. Electrochem. Soc.,154(2007) A875-A881.
[112] J. Stöhr, NEXAFS Spectroscopy; Springer-Verlag, New York, 1992.
[113] H. B. Garg, E. A. Stern, D. Norman, X-ray Absorption in Bulk and Surfaces, World Scientific Publishing Co.; Singapore, 1994.
[114] A. Deb, U. Bergmann, S.P. Cramer, E.J. Cairns, “Structural investigations of LiFePO4 electrodes and in situ studies by Fe X-ray absorption spectroscopy”, Electrochim. Acta, 50 (2005) 5200-5207.
[115] J. K. Chang, M.T. Lee, W.T. Tsai, “In situ Mn K-edge X-ray absorption spectroscopic studies of anodically deposited manganese oxide with relevance to supercapacitor applications” J. Power Sources, 166 (2007) 590-594.
[116] M. T. Lee, J. K. Chang, Y. T. Hsieh, W. T. Tsai, “Annealed Mn-Fe Binary oxides for Supercapacitor Applications”, J. Power Sources, 185(2008) 1550-1556.
[117] M. Seyama, Y. Iwasaki, A. Tate, I. Sugimoto, “Room-Temperature Ionic-Liquid-Incorporated Plasma-Deposited Thin Films for Discriminative Alcohol-Vapor Sensing”, Chem. Mater. 18(2006) 2656-2662
[118] C. S. Santos, S. Baldelli, “ Surface Orientation of 1-Methyl-, 1-Ethyl-, and 1-Butyl-3-methylimidazolium Methyl Sulfate as Probed by Sum-Frequency Generation Vibrational Spectroscopy”, J. Phys. Chem. B 111(2007) 4715-4723
[119] C. Kolbeck, M. Killian, F. Maier, N. Paape, P. Wasserscheid, H. P. Steinrück, “ Surface Characterization of Functionalized Imidazolium-Based Ionic Liquids”, Langmuir 24(2008) 9500-9507
[120] V. Lockett, R. Sedev, C. Bassell, J. Ralston, “Angle-resolved X-ray photoelectron spectroscopy of the surface of imidazolium ionic liquids”, Phys. Chem. Chem. Phys. 10(2008) 1330-1335