Recent climate change concerns have led to the desire for more sustainable energy sources, and fuel cells have demonstrated the potential to be strong contenders to fill that role. Among them, anion exchange membrane fuel cells (AEMFCs) have shown promise in being able to mitigate one of the primary drawbacks of fuel cell technology: cost. Non-PGM catalysts have the potential to be improved via controlled nanoparticle (NP) dispersion and then implemented into the AEMFCs to achieve the same or greater efficiency as current PEMFC technology. This can be accomplished by coating the membrane of the MEA in the AEMFC with non-PGM nanoparticles. Prior research has found that silver (Ag) exhibits similar catalytic properties to platinum in AEMFCs. Therefore, we propose that by using different thiol lengths to control the distribution and size of synthesized Ag nanoparticles that are deposited on the fuel cell membrane, an optimized MEA which utilizes significantly reduced amounts of platinum (Pt) can be developed. In this study, Ag nanoparticles synthesized with either hexanethiol (C6), octanethiol (C8), or decanethiol (C10) using the Brust nanoparticle synthesis method are dispersed on a commercial Sustainion membrane via a Langmuir-Blodgett trough at different surface pressures. In order to find the optimal Ag nanoparticle size, the performance of AEMFCs modified with different Ag nanoparticle sizes were compared to each other and control. The control to set a benchmark performance was a Membrane electrode assembly (MEA) with a Sustainion X37-50 Grade RT membrane that had not been sprayed with Ag nanoparticles, with an active area of 5cm2 and a platinum concentration of 0.76 mg/cm2. The control AEMFC reached a peak power density of 0.42 W/cm2. The highest peak power densities achieved with Ag NPs was at 10 mN/m surface pressure, with the highest being C8 at 0.750 W/cm2 which was 69.4% greater than the power density of the control and the sprayed nanoparticles. The resulting power densities revealed a strong dependence of thiol length (i.e., NP size) and surface pressure (i.e., the distance between the particles) on power output. This huge power enhancement cannot be attributed to the increase in the total amount of nanoparticles, since only a few micrograms of catalyst is added to the amount already in the MEA. There must be some kind of synergy in the system. Further experiments, as well as DFT simulations, are in progress to better understand this phenomenon.

Enhancing the performance of anion exchange membrane fuel cells (AEMFCs) using silver nanoparticles

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.