물 전기분해용 Pt-SPE 전극촉매 제조에 관한 연구(II) -표면 처리의 영향(산소 이온빔)-

김지윤; 박종호; 강문식; 조영일; 최성창; 고석근

HWAHAK KONGHAK, Vol.37, No.2, 349-354, April, 1999

A Study on Preparation of Pt-SPE Electrocatalyst for Water Electrolysis(II) - The Effect of Surface Treatment(Oxygen ion Beam) -

김지윤, 박종호, 강문식, 조영일, 최성창, 고석근

초록

고체고분자전해질(SPE)로 Nafion 117을, H₂PtCl₆와 NaBH₄를 전극물질과 환원제로 각각 사용하여 Pt-SPE복합체를 제조하였다. 담지 전에 막과 전극촉매간의 접합력을 항상시키기 위해서 산소 기체를 이용하여 이온을 발생시킨 후 막을 표면처리 하였다. 이온 조사량은 5×10¹⁵-1×10¹⁷ ions/cm², 이온빔 에너지는 1 keV였으며 산소 기체를 8 sccm(ml/min)으로 공급하였다. 표면처리를 한 후에 Pt-SPE복합체를 제조하였다. 제조한 Pt-SPE복합체의 형태학적 특성은 SEM을 통하여 알아보았고, 전기화학적 특성은 순환전류전압도(cyclic voltammogram, CV)와 교류임피던스 분광법(a.c, impedance spectroscopy)으로 분석하였다. 표면처리는 막과 전극촉매 간의 접합력을 향상시키고 접촉저항을 감소시켰다. 정전류 법(galvanostatic method)에 의한 물 전기분해 실험에서 이온 조사량이 증가할수록 조전압은 감소하였다. 전류밀도 1 A/cm²(온도 25 ℃)에서 조전압은 비처리한 막에 제조한 Pt-SPE 복함체의 경우 3.OV를 나타내었다. 산소 이온빔으로 처리된 후 제조한 Pt-SPE복합체는 이온 조사량이 1×10¹⁷ions/cm²일 때 가장 낮은 값을 나타냈으며 이때의 조전압은 2.8V를 나타냈다.

Pt-SPE composite using the Nafion 117 membrane as a solid polymer electrolyte(SPE) were prepared by counter current method. H₂PtCl₆ and NaBH₄ were used as the electrode material and reducing agent, respectively. For additional improvement of adhesion property between the membrane and electrocatalyst, we etched surface of the Nafion 117 membranes with ion beam by oxygen gas prior to platinum plating. Ion doses were varied from 5×10¹⁵ to 1×10¹⁷ ions/cm², ion beam energy was 1 keV and amount of blowing oxygen gas was 8 sccm(ml/min). After surface treatment, we fabricated Pt-SPE composite. Surface morphology of the prepared Pt-SPE composite was examined with a SEM(scanning electron microscope) and their electrochemical property of Pt-SPE composite was characterized by cyclic voltammetry and a.c. impedance analysis. Surface treatment showed improvement of adhesive property and reduced contact resistance between the membrane and electrocatalyst. In water electrolysis performance using galvanostatic method, the cell voltage decreased as the ion doses increased. For non treated Pt-SPE composite, the cell voltage showed 3.0 V at a current density 1 A/cm² and 25 ℃. At ion doses of 1×10¹⁷ions/cm², the cell voltage of treated Pt-SPE composite with oxygen ion beam showed a minimal value of 2.8 V.

Keywords:Pt-SPE Composite;Solid Polymer Electrolyte(SPE);ion Beam;Surface Treatment;Water Electrolysis;Cyclic Voltammetry;A.C. Impedance Spectroscopy

[References]

Millet P, Pineri M, J. Appl. Electrochem., 19, 162 (1989)
Millet P, Durand R, Dartyge E, Tourillon G, Fontaine A, J. Electrochem. Soc., 140, 5 (1993)
Lawrance RJ, Hampslead NH, Wood LD, Mass A, U.S. Patent, 4,272,353 (1981)
Holze R, Ahn J, J. Membr. Sci., 73, 87 (1992)
Sakai T, Kawami Y, Takenaka H, Torikai E, J. Electrochem. Soc., 137, 12 (1990)
Millet P, Alleau T, Durand R, J. Appl. Electrochem., 23, 322 (1993)
Takenaka H, Torikai E, Kawami Y, Wakabayashi N, Int. J. Hydrog. Energy, 7, 5 (1982)
Sakai T, Takenaka H, Torikai E, J. Electrochem. Soc., 133, 1 (1986)
Seok JW, Choi SC, Jang HG, Jung HJ, Choi WK, Koh SK, J. Korean Vaccum Soc., 6, 200 (1997)
Kang MS, Ph.D. Thesis, Yonsei Univ., Seoul, Korea (1997)
Kang MS, Joe YI, J. Power Sources, Accepted
Chae JK, Kang MS, Han HS, Shul YG, Joe YI, HWAHAK KONGHAK, 34(6), 706 (1996)
Lu PWT, Srinivasan S, J. Appl. Electrochem., 9, 269 (1979)
Xing XK, Liu CC, Electroanalysis, 3, 111 (1991)
Nakajima H, Takakuwa Y, Kikuchi H, Fujikawa K, Kita H, Electrochim. Acta, 32, 5 (1987)
Kita H, Nakajima H, Electrochim. Acta, 31, 2 (1986)
Walls JM, "Methods of Surface Analysis," Cambridge Univ., Cambridge (1987)
Blurton KF, Greenberg P, Oswin HG, Rutt DR, J. Electrochem. Soc., 119, 5 (1972)
Liu R, Her WW, Fedkiw PS, J. Electrochem. Soc., 139, 1 (1992)

[1] Millet P, Pineri M, J. Appl. Electrochem., 19, 162 (1989)

[2] Millet P, Durand R, Dartyge E, Tourillon G, Fontaine A, J. Electrochem. Soc., 140, 5 (1993)

[3] Lawrance RJ, Hampslead NH, Wood LD, Mass A, U.S. Patent, 4,272,353 (1981)

[4] Holze R, Ahn J, J. Membr. Sci., 73, 87 (1992)

[5] Sakai T, Kawami Y, Takenaka H, Torikai E, J. Electrochem. Soc., 137, 12 (1990)

[6] Millet P, Alleau T, Durand R, J. Appl. Electrochem., 23, 322 (1993)

[7] Takenaka H, Torikai E, Kawami Y, Wakabayashi N, Int. J. Hydrog. Energy, 7, 5 (1982)

[8] Sakai T, Takenaka H, Torikai E, J. Electrochem. Soc., 133, 1 (1986)

[9] Seok JW, Choi SC, Jang HG, Jung HJ, Choi WK, Koh SK, J. Korean Vaccum Soc., 6, 200 (1997)

[10] Kang MS, Ph.D. Thesis, Yonsei Univ., Seoul, Korea (1997)

[11] Kang MS, Joe YI, J. Power Sources, Accepted

[12] Chae JK, Kang MS, Han HS, Shul YG, Joe YI, HWAHAK KONGHAK, 34(6), 706 (1996)

[13] Lu PWT, Srinivasan S, J. Appl. Electrochem., 9, 269 (1979)

[14] Xing XK, Liu CC, Electroanalysis, 3, 111 (1991)

[15] Nakajima H, Takakuwa Y, Kikuchi H, Fujikawa K, Kita H, Electrochim. Acta, 32, 5 (1987)

[16] Kita H, Nakajima H, Electrochim. Acta, 31, 2 (1986)

[17] Walls JM, "Methods of Surface Analysis," Cambridge Univ., Cambridge (1987)

[18] Blurton KF, Greenberg P, Oswin HG, Rutt DR, J. Electrochem. Soc., 119, 5 (1972)

[19] Liu R, Her WW, Fedkiw PS, J. Electrochem. Soc., 139, 1 (1992)