압력상승에 따른 Pt(111)표면의 메탄올 분해와 피독 현상

Abstract

DMFC(Direct Methanol Fuel Cell) 는 메탄올을 직접 산화하고 수소를 생성하여 에너지를 사용할 수 있는 연료전지이다. 이는 친환경 휴대용 battery 역할을 할 수 있는 중요한 에너지 저장 장치로 많은 관심을 받고 있다. 이때 DMFC 구조 중 Anode는 연료 극으로써 메탄올의 원활한 분해 반응을 유도하기 위하여 백금(Platinum) 촉매가 필수적이다. 그러나 백금(Platinum)표면에서 메탄올의 분해 과정은 매우 복잡하고 모호하므로 이에 따른 기준이 될 수 있는 실험이 필요하다고 판단되었다.

본 연구에서는 single crystal Pt(111) 표면에서 메탄올의 압력 상승에 따른 분해과정을 알아보고자 먼저 Ar+ sputtering과 annealing으로 clean Pt(111)surface의 스펙트럼을 확인하였다. 그 다음 온도는 470K 정도로 유지하면서 메탄올의 압력을 1.0×〖10〗^(-6), 1.8×〖10〗^(-3) , 1.0×〖10〗^(-1)torr으로 상승 시켰다. 이에 따른 실험을 준비하기 위하여 상압광전자분광기(Ambient Pressure Photoelectron Spectroscopy, APPES)를 사용하였다. 그 결과 순수한 백금(Platinum)촉매 역시 메탄올의 양에 따라 분해가 가능함을 알 수 있었다. 또한 메탄올은 O-H결합의 분해에 따른 과정을 따르고 있으나 표면에서 carbon의 증가에 의한 CO poisoning로 인하여 분해 과정의 효율성이 점차 감소되고 있음을 알 수 있었다. |DMFC (Direct Methanol Fuel Cell) is the fuel cell which is capable of oxidizing methanol directly and it uses energy which is generated from hydrogen. So it receives a lot of attention as important energy storage for eco-friendly portable battery. At this time, ‘Anode’, which is one of the DMFC systems, needs Platinum catalyst to lead a good decomposition reaction. However, the decomposition of methanol on the surface of Platinum is complex and equivocal. So, it is judged that an experiment as a criterion is necessary.

In this study, clean Platinum surface spectrum was checked through Ar+ sputtering and annealing at first to investigate decomposition following elevated pressure of methanol on the surface of single crystal. Next, the pressure of methanol increased to 1.0×〖10〗^(-6), 1.8×〖10〗^(-3) , 1.0×〖10〗^(-1)torr holding temperature about 470K. Consequently, APPES (Ambient Pressure Photoelectron Spectroscopy) was used for preparing for this experiment. As a result, it was shown that single crystal Platinum could be decomposed depending on the quantity of methanol. Also, while methanol follows decomposition of O-H bond scission, it was proved that efficiency of decomposition reaction decreased due to CO poisoning.; DMFC (Direct Methanol Fuel Cell) is the fuel cell which is capable of oxidizing methanol directly and it uses energy which is generated from hydrogen. So it receives a lot of attention as important energy storage for eco-friendly portable battery. At this time, ‘Anode’, which is one of the DMFC systems, needs Platinum catalyst to lead a good decomposition reaction. However, the decomposition of methanol on the surface of Platinum is complex and equivocal. So, it is judged that an experiment as a criterion is necessary.

In this study, clean Platinum surface spectrum was checked through Ar+ sputtering and annealing at first to investigate decomposition following elevated pressure of methanol on the surface of single crystal. Next, the pressure of methanol increased to 1.0×〖10〗^(-6), 1.8×〖10〗^(-3) , 1.0×〖10〗^(-1)torr holding temperature about 470K. Consequently, APPES (Ambient Pressure Photoelectron Spectroscopy) was used for preparing for this experiment. As a result, it was shown that single crystal Platinum could be decomposed depending on the quantity of methanol. Also, while methanol follows decomposition of O-H bond scission, it was proved that efficiency of decomposition reaction decreased due to CO poisoning.