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Summary: Gas diffusion layer (GDL) plays an important role in the performance of membrane electrode assembly (MEA) in polymer electrolyte fuel cells. In this work, 2‐type MEAs were prepared by 2 different GDLs of 29  BC and 29‐WUT, and the performance were investigated using polarization curve methods. The performance of MEA with 29‐WUT was 120 mV higher than 29  BC at 1600 mA/cm2. Electrochemical impedance spectroscopy (EIS) was applied to measure the mass transport resistance of 2‐type MEAs under normal running condition. The results of EIS showed that the mass transport resistance of 29  BC was 3.15 times higher than that of 29‐WUT at 1600 mA/cm2. To clarify this phenomenon, limiting current methods were applied under diluting oxygen concentration, low humidity, and high flow rate conditions. The results of limiting current methods showed that both the total oxygen transport resistance and the molecular diffusion resistance in the GDL of 29  BC were larger than that of 29‐WUT due to the lower porosity of gas diffusion substrate in 29  BC. As a result, EIS can be well combined with limiting current methods to analyze oxygen transport resistance in GDLs of fuel cells. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate a two-step analysis procedure that enables an in-depth understanding of the localized charge trapping and charge decay mechanisms in metal nanocrystal (MNC)-embedded high-κ/SiO2 gate stacks. The results clearly reveal that vertical charge loss and lateral charge diffusion are two competing mechanisms, and they can be identified by discharging current measurements at elevated temperatures and the Kelvin force microscopy characterization. It is found that the MNC with higher work function has a lower inter-dot charge tunneling probability, which is favorable for improved retention in memory applications. However, the vertical charge loss during the initial decay period is a trade-off and it could be minimized by using a dual-layer MNC structure. [ABSTRACT FROM AUTHOR]