TY - JOUR
T1 - Effect of alcohol content on the ionomer adsorption of polymer electrolyte membrane fuel cell catalysts
AU - Wu, Dan
AU - Kayo, Nana
AU - Jayawickrama, Samindi Madhubha
AU - Phua, Yin Kan
AU - Tanaka, Naoki
AU - Fujigaya, Tsuyohiko
N1 - Funding Information:
To study the effects of PBI on the PEMFC performance, a MEA having CB/PBI/Pt as the electrode catalyst (MEACB/PBI) was prepared using water-rich (w-MEACB/PBI) and alcohol-rich (a-MEACB/PBI) inks. Fig. 9 a–f shows the SEM images of the CL surface of w-MEACB/PBI and a-MEACB/PBI. From the low-magnification SEM images, microvoids were also observed in w-MEACB/PBI (Fig. 9a and b), similar to w-MEACB. In the polarization measurement, w-MEACB/PBI exhibited higher cell potential at all current density regions compared to a-MEACB/PBI (Fig. 9g). However, the difference of the maximum power density between w-MEACB/PBI and a-MEACB/PBI was 13%. This small difference suggests that the Pt utilization efficiency does not largely depend on the solvent composition in the case of the PBI system, unlike the MEACB systems. Indeed, w-MEACB/PBI and a-MEACB/PBI showed relatively low Rp of 0.33 and 0.44 Ω cm−1 [47], respectively (Fig. 9h). In addition, in the in-situ CV measurements, both w-MEACB/PBI and a-MEACB/PBI exhibited relatively high ECSA values of 75.5 and 62.4 m2 g−1 Pt, respectively (Fig. 9i and j). Such a low Rp values and high in-situ ECSA for two MEAs clearly supports the higher Nafion adsorption aided by PBI yielding a good proton conduction path even in an alcohol-rich solvent (Fig. 10). We previously reported that the effect of the homogeneous Nafion coating by the aid of PBI layer was quite obvious especially at low I/C, namely, a-MEACB/PBI exhibited high maximum power density of 750 mW cm−2 even at I/C = 0.2, while a-MEACB showed low maximum power density of 190 mW cm−2 at I/C = 0.2 [47].The Nafion adsorption analysis (adsorption isotherm, zeta potential, particle size, and sedimentation experiments) and MEA analysis (impedance, in-situ CV, and polarization analyses) revealed the crucial role of the interaction between Nafion and carbon surface on the MEA performance. The use of water-rich solvent and/or PBI-coated CB offers the stronger interaction between Nafion and carbon supports than alcohol-rich solvent, resulting in the homogenous distribution of Nafion in the CL and thereby higher power densities. In the PBI system, the solvent composition does not significantly affect the MEA performance and alcohol-rich solvent can be used, which is advantageous to the process of CL fabrication.This research was supported by “Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM)” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), KAKENHI [grant no. JP18H01816], the Bilateral Program [grant no. AJ190078] of the Japan Society for the Promotion of Science (JSPS), the CREST program [grant no. AJ199002] and fellowships towards the creation of science technology innovation [grant no. JPMJFS2132] of the Japan Science and Technology Agency (JST).
Funding Information:
This research was supported by “ Advanced Research Infrastructure for Materials and Nanotechnology in Japan (ARIM) ” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT) , KAKENHI [grant no. JP18H01816 ], the Bilateral Program [grant no. AJ190078 ] of the Japan Society for the Promotion of Science (JSPS), the CREST program [grant no. AJ199002] and fellowships towards the creation of science technology innovation [grant no. JPMJFS2132] of the Japan Science and Technology Agency (JST).
Publisher Copyright:
© 2022 Hydrogen Energy Publications LLC
PY - 2022
Y1 - 2022
N2 - Catalyst layers (CL) composed of catalyst composites and an ionomer are key components in polymer electrolyte membrane fuel cells (PEMFCs). In particular, the preparation conditions of the CL, starting from the dispersion of the catalyst composite dispersion with an ionomer, largely affect the PEMFC performance. In this study, the effects of alcohol content in the dispersion solvent were investigated using two binary mixtures composed of water and ethanol. In addition, Pt-loaded carbon black (CB) and Pt-loaded polymer-wrapped CB were used as the catalyst composites to study the effects of the alcohol contents on the interaction between ionomer and surface of the carbon supports. The CL prepared using the water-rich (80 wt% water) solvent achieved a higher PEMFC performance compared to that using the alcohol-rich (13 wt% water) solvent, which is ascribed to the stronger interaction between the ionomer and CB surface under water-rich conditions. Using the polymer-wrapped CB, the difference of the PEMFC performance between the CLs from the water-rich and alcohol-rich dispersions was minimal because of the comparable interaction between the ionomer and wrapping polymer surface in both solvents. Therefore, the control of the interaction between the ionomer and catalyst composites is crucial to controlling the PEMFC performance.
AB - Catalyst layers (CL) composed of catalyst composites and an ionomer are key components in polymer electrolyte membrane fuel cells (PEMFCs). In particular, the preparation conditions of the CL, starting from the dispersion of the catalyst composite dispersion with an ionomer, largely affect the PEMFC performance. In this study, the effects of alcohol content in the dispersion solvent were investigated using two binary mixtures composed of water and ethanol. In addition, Pt-loaded carbon black (CB) and Pt-loaded polymer-wrapped CB were used as the catalyst composites to study the effects of the alcohol contents on the interaction between ionomer and surface of the carbon supports. The CL prepared using the water-rich (80 wt% water) solvent achieved a higher PEMFC performance compared to that using the alcohol-rich (13 wt% water) solvent, which is ascribed to the stronger interaction between the ionomer and CB surface under water-rich conditions. Using the polymer-wrapped CB, the difference of the PEMFC performance between the CLs from the water-rich and alcohol-rich dispersions was minimal because of the comparable interaction between the ionomer and wrapping polymer surface in both solvents. Therefore, the control of the interaction between the ionomer and catalyst composites is crucial to controlling the PEMFC performance.
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U2 - 10.1016/j.ijhydene.2022.11.116
DO - 10.1016/j.ijhydene.2022.11.116
M3 - Article
AN - SCOPUS:85144024428
JO - International Journal of Hydrogen Energy
JF - International Journal of Hydrogen Energy
SN - 0360-3199
ER -
