The precise mechanism of performance degradation in polymer electrolyte membrane fuel cells (PEMFCs) under the fuel starvation condition is investigated by simultaneously monitoring the potential behavior and exhaust gas from the anode using the hydrogen reference electrode and in situ online mass spectrometry. Interestingly, the water electrolysis begins at a lower potential range, and carbon oxidation occurs at a higher range as the alternative reaction to hydrogen oxidation. Thus, carbon corrosion, which is detrimental to cell performance, can be reduced by extending the duration of the water electrolysis reaction. In this regard, the introductions of the graphitized carbon support and water electrolysis catalyst to anode are effective in alleviating the damage due to fuel starvation by rendering the dominant alternative reaction to continue the water electrolysis.

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A novel synthetic process was developed to synthesize nano-sized core-shell catalysts through atomic rearrangement by heattreatment. Agglomeration of nanoparticles caused by the high-temperature heat-treatment was alleviated by using a modified protective coating method. In this method, the carbon layer formed by the carbonization of polydopamine serves as a protective coating layer, which suppresses the sintering of the catalyst particles continuously until the high-temperature heat-treatment is completed. Later, the carbonized carbon layer is removed by ozone treatment because it blocks the active site of the catalyst. Since ozone is a highly oxidative gas, it can selectively remove the carbon layer at room temperature in just 7 minutes without affecting the physical properties of the catalyst itself, which makes this method suitable for mass production. The Pt-based alloy catalyst was prepared by this unique process was proved to have a Pt-rich shell structure, and the particles can remain small (∼5 nm) even after high-temperature heat-treatment, thus exhibiting high oxygen reduction reaction (ORR) activity in fuel cells.

Polymer electrolyte membrane fuel cells (PEMFCs) has attracted great attention in transportation and stationary applications with zero emissions and high efficiency compared to conventional combustion engines. However, various factors limit the lifespan of PEMFCs, which remain a major obstacle to large-scale commercialization. In particular, corrosion of the carbon support is one of the main causes of fatal and irreversible deterioration of PEMFCs performance. If the hydrogen fuel supply is insufficient to maintain current demand due to poor water management or fuel depletion at the anode, carbon corrosion may occur on the anode side. In this fuel starvation condition, reactions that take place in place of hydrogen oxidation, such as water electrolysis and oxidation of the carbon support, compensate for the current shortage. The exact deterioration mechanism of PEMFCs in fuel starvation is investigated by simultaneously monitoring the potential behavior from the anode and the exhaust gas using hydrogen reference electrodes and in situ online mass spectrometry. Interestingly, water electrolysis starts at a lower potential range and carbon oxidation occurs at a higher range as an alternative reaction to hydrogen oxidation. Thus, carbon corrosion, which is detrimental to cell performance, can be reduced by extending the duration of the water electrolysis reaction. In this regard, the introductions of the graphitized carbon support and water electrolysis catalyst to the anode are effective in alleviating damage due to fuel starvation by making a dominant alternative reaction to continue electrolysis of water. And this alternative reaction is Monitored with a hydrogen reference electrode and using on-site online mass spectrometry.