Experimental Investigation on the Effect of Precursor Concentration, pH, and Potential on the Performance of Electrodeposited Electrode Used in HT-PEMFC

Abstract With the advantages of enhanced reaction kinetics and compatibility with reformed gas, etc., high-temperature proton exchange membrane fuel cells (HT-PEMFCs) have shown promising prospects in recent years. As a rapid and efficient preparation method of electrodes, the application of electrodeposition in the membrane electrode assemblies (MEAs) is a critical research topic for the commercialization of HT-PEMFCs. This study reports an electrodeposition strategy to synthesize different morphologies of platinum (Pt) nanoparticles (NPs) on carbon paper as gas diffusion electrodes (GDEs) of HT-PEMFC through regulating precursor concentration, pH, and potential. Concentration shows scarcely any influence on the morphology of Pt NPs as well as the electrochemically active surface area (ECSA), whereas both pH and potential dominate morphological evolution through different mechanisms, leading to a great difference in ECSA. The rapid hydrogen evolution reaction (HER) kinetics caused by low pH and potential is proven to be negative on the Pt electrodeposition process. Pt NPs with various nanostructures (petal-shaped, sphere-shaped, thorn-shaped, coral-shaped, and polyhedral) are synthesized in this work. Notably, Pt nanoflowers electrodeposited at −0.7 V [versus saturated calomel electrode (SCE)] exhibited superior performance with the ECSA of 161.33 cm2/mg. However, when GDEs with electrodeposited Pt NPs are directly applied to HT-PEMFC, due to the phosphoric acid poisoning, severe performance degradation is observed. The results show the substantial challenges of implementing electrodeposition in HT-PEMFCs, providing essential insights for future research.