Highly Dispersed Pt on Ceria with N-Doped Carbon As High Durable Catalyst for ORR and High Tolerant to H2s and CO for HOR in PEMFCs
Authors: Zeng Rong , Liu Ling , Yan Jiasi , Jiang Lijun 
Published: February 2024

Proton Exchange Membrane Fuel Cells (PEMFCs) are one of the most promising clean and efficient energy conversion devices. However, carbon supported Pt-based electrocatalysts, widely used in PEMFCs, show poor stability due to the carbon oxidation and unstable Pt in practical application. Hydrogen starvation at anode and unprotected startup/shutdown of PEMFCs can arouse high potential over 1.3V resulting in severe carbon corrosion and irreversible performance loss. With increased electron conductivity, the doped metal oxides Ti3O5Mo0.2Si0.4 (TOMS) [1], Nb-TiO2
[
2], Ta0.3Ti0.7O2
[
3], Sb-SnO2
[
4], W-SnOx and TiOx
[
5] show great potential as durable catalyst supports that can stand over 1.0V for PEMFCs. Furthermore, strong metal support interactions (SMSI) of Pt and the support also enhance the stability of Pt.

CeO2 which exhibits good dynamic oxygen storage and release capacity, strong redox capacity, was deposited on N-doped carbon (NC) as support. Pt was highly dispersed on the CeO2/NC to form Pt/CeO2/NC catalyst. Accelerated degradation test (ADT) was carried out by sweeping voltage from 1.0V to 1.2V on a GC disk with a Pt loading of 20 μgPt·cm-2 in the oxygen saturated 0.1M HClO4 electrolyte with a scan rate of 10mV·s-1, while the Pt ring was held at 1.2V vs. RHE. Fig 1 shows the morphology of as-prepared CeO2/NC and Pt/CeO2/NC, the LSV and CV of Pt/CeO2/NC after different cycles of ADT. The specific mass activity at 0.9ViR free (im@0.9V) for oxygen reduction reaction (ORR) of Pt/CeO2/NC was 105mA×mg-1 and slightly increased about 8% after 10000 cycles.

On the other hand, precious metal on CeO2 is high efficient CO oxidation catalyst [6-7] and widely applied for H2 purification from reformate gases. CeO2 was applied as H2S oxidant [8] too. This broadens the Pt/CeO2/NC as a high H2S and CO tolerant catalyst for hydrogen oxidation reaction (HOR). The high dispersion of Pt nano particle, the interaction between the poison gases and Pt and/or CeO2 was believed to contribute. The theoretical and experimental details will be presented at the symposium.

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Figure 1