직접 메탄올 연료전지용 메탄올 센서의 백금 두께의 변화에 따른 전류-전압 특성 변화

I-V Characteristics of a Methanol Sensor for Direct Methanol fUel Cell(DMFC) as a Function of Deposited Platinum(Pt) Thickness

직접 메탄올 연료전지는 간단한 구조와 디자인 그리고 높은 에너지 밀도와 에너지 변환 효율등의 장점으로 인하여 휴대용 장치들의 전력원으로 사용된다. 본 논문에서는 직접 메탄올 연료전지의 연료 농도를 감지하기 위한 얇은 나피온 막과 Pt 촉매전극의 합성으로 만들어진 메탄을 센서를 제작하였다. 제작된 메탄을 센서를 사용하여 메탄올 농도와 촉매전극(Pt)의 두께 변화에 따른 전류-전압 특성을 분석하였다. Pt 촉매전극 10nm, 전압이 1V 이고 메탄올 농도 1, 2, 3M일 때 전류 값이 각각 $1.30{\times}10^{-6}A,\;1.96{\times}10^{-6}A,\;2.80{\times}10^{-6} A$ 이었다. 메탄올 농도를 2M로 고정하고 촉매전극의 두께를 5, 10, 15nm로 변화시켰을 때 전류 값은 각각 $3.06{\times}10^{-6}A,\;1.96{\times}10^{-6}A,\;1.00{\times}10^{-6}A$ 이었다. 촉매전극이 얇을수록 전류가 증가하고 전기화학반응이 더 활발히 일어나는 것으로 사료된다.

The direct methanol fuel cell (DMFC) is a promising power source for portable applications due to many advantages such as simple construction, compact design, high energy density, and relatively high energy-conversion efficiency. In this work, an electrochemical methanol sensor for monitoring the methanol concentration in direct methanol fuel cells was fabricated using a thin composite nafion membrane as the electrolyte. We have analyzed the I-V characteristic of the fabricated methanol sensor as a function of methanol concentration, catalyst electrode and platinum(Pt) thickness. The fabricated sensor was analyzed by I-V measurement with various methanol concentration. When we measured the sensor characteristics with 10nm Pt and at 1V, the current value was $1.30{\times}10^{-6}A,\;1.96{\times}10^{-6}A\;and\;2.80{\times}10^{-6} A$ for three methanol concentration of 1M, 2M and 3M, respectively. When the methanol concentration was fixed at 2M, the current value of the fabricated device with Pt layers of 5, 10 and 15 nm thickness was $3.06{\times}10^{-6}A,\;1.96{\times}10^{-6}A\;and\;1.00{\times}10^{-6}A$, respectively. These results lead us to the conclusion that when the methanol concentration increases, the output current increases and when the catalyst electrode become thinner, the current increase more. It showed that, the thinner the catalyst electrode, the more electrochemistry become activation.