Enhanced Stability of Novel Hierarchical Carbon Supports in PEMFC Application
Authors: Sepp Silver , Nerut Jaak , Vaarmets Kersti , Kanarbik Rait , Tallo Indrek , Kurig Heisi , Lust Enn 
Published: February 2020

Proton exchange membrane fuel cell (PEMFC) is one of the most promising candidates as an environmentally clean power source in various applications. The efficiency of a catalyst depends strongly on the selection of an appropriate support material. The instability of carbon supports in fuel cell working conditions is the major obstacle hindering the commercialization of PEMFCs. Therefore, novel carbon supports are being sought for fuel cell application [1, 2]. Hierarchical microporous-mesoporous carbon supports were prepared from molybdenum carbide using the high temperature chlorination method at different synthesis temperatures within the range from 600 °C to 1000 °C. Prepared materials exhibited high specific surface area, but they differed from one another in their structural properties, such as pore size distribution and the ratio of micro- and mesopores volumes [1, 3-4].
The platinum nanoparticles were deposited onto the carbon support using the sodium borohydride method. Thermogravimetric analysis, X-ray diffraction, low temperature nitrogen sorption and high resolution transmission electron microscopy methods were used to characterize the structure of the synthesized materials.
Prepared catalysts were used in the single cell measurements. The polarization curves and chronopotentiometric measurements were conducted to evaluate the activity and stability of the catalyst materials synthesized. The electrochemically active surface area values were calculated and used to estimate the contact surface of platinum nanoparticles and Nafion electrolyte. The resistance of electrolyte, polarization resistance and activation energy values have been established from electrochemical impedance spectroscopy data. Prepared materials with well-defined properties are excellent objects to study the impact of the carbon catalyst support properties on the performance and stability of a PEMFC single cell.
The main aim of this work was to study the time stability (Fig. 1) of Pt nanoclusters activated microporous-mesoporous carbon supports in fuel cell application and to compare the properties of these materials with commercial carbon Vulcan XC72 used as catalyst support. It was found that the novel synthesized carbon supports are very stable and thus suitable for PEMFC application.

Acknowledgements.

This work was supported by Estonian target research project IUT20-13, Personal Research Grant PUT55, Estonian Centre of Excellence Projects No. 2014-2020.4.01.15-0011 and 3.20101.11-0030.

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Figure 1. Galvanostatic life-time measurements for single cells with synthesized and commercial carbon used as catalyst support.

Figure 1