Energy Sciences, Engineering Sciences

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Objective: Development of carbon-free electrocatalysts to prevent carbon corrosion under electrochemical conditions during cell operation. Enrichment of the carbon-free catalyst matrix with ‘oxygen nano reservoirs’ to ensure improved performance under oxygen lean conditions. Surface characterization and quantification of the oxygen vacancy sites, evaluation of the catalyst using Raman Spectroscopy. Demonstration of single cells of PEM fuel cells (up to 45 cm2) made up of carbon-free cathodes. Complete analysis of the single cells of PEM fuel cells with carbon-free cathodes by comparing with its carbon-based counterpart to critically evaluate the performance and durability characteristics. Performance evaluation under oxygen rich and oxygen lean conditions to ensure power output under diverse feed availability conditions (such as taking air directly from the atmosphere).

Summary: With a focused target of deploying PEMFCs for both stationery and automobile applications, CSIR-NCL is working with other CSIR labs and industries. We observed that carbon corrosion and oxygen starvation are the two major system specific hurdles. These issues are more severe in the case of high temperature PEMFCs (HT-PEMFCs) due to the combined effect of high temperature (150-160oC), free H3PO4 from the acid doped PBI membrane and the operating potential (0.50-0.60 V). Since oxygen solubility in H3PO4 is less, the cell performance drops under oxygen lean conditions. Hence, an electrocatalyst which is carbon-free with features to enrich local oxygen concentration can make radical changes in the durability and performance characteristics of PEMFCs. These issues must be addressed by judiciously designing a catalyst from suitable carbon-free substrates with provision for oxygen enrichment at the active sites. The methodologies will be strategically planned to ensure high electrical conductivity and low electrochemical and acid corrosion of the substrate. The nanomaterial architecture of the substrate and dispersion of Pt will be achieved without compromising the active surface area of Pt. Also, the substrate will be embedded or anchored with oxygen buffering systems to act as “oxygen nano-reservoirs” and maintain oxygen supply to the active sites under oxygen lean conditions. This will be followed by the development and demonstration of single cells of 45 cm2area. Here, the nature of the oxygen reservoirs is also going to play a crucial role in the dispersion of Pt and hence the final catalyst. XPS and Raman spectroscopy have been extensively employed to look at the oxygen storage properties and the vacancy sites on oxide materials. We intend to employ these two tools to characterize the catalyst material pre and post reaction to gain molecular level insights.

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