Nanoscale membrane electrode assemblies based on porous anodic alumina for hydrogen–oxygen fuel cell

Abstract

In this paper, we demonstrate that nanoscale membrane electrode assemblies, functioning in a H 2 /O 2 fuel cell, can be fabricated by impregnation of anodic alumina porous membranes with Nafion® and phosphotungstic acid. Porous anodic alumina is potentially a promising material for thin-film micro power sources because of its ability to be manipulated in micro-machining operations. Alumina membranes (Whatman, 50 μm thick, and pore diameters of 200 nm) impregnated with the proton conductor were characterized by means of scanning electron microscopy, X-ray diffraction, and thermal analysis. The electrochemical characterization of the membrane electrode assemblies was carried out by recording the polarization curves of a hydrogen-oxygen 5 cm 2 fuel cell working at low temperatures (25÷80°C) in humid atmosphere. Our assemblies realized with alumina membranes filled with phosphotungstic acid and Nafion® reach respectively the peak powers of 20 and 4 mW/cm 2 at room temperature using hydrogen and oxygen as fuel and oxidizer.

Understanding methods of preparation and characterization of pore-filling polymer composites for proton exchange membranes: a beginner’s guide

“…On the other hand, in 10:9 v/v IPA/water mixture, a better solvent for the perfluorinated backbone, C* increases to ~4.5 g l −1 (Zhang et al 2008). As previous attempts to fill PCTE or AAO pores with Nafion (Leddy and Vanderborgh 1987, Fang and Leddy 1995, Raghav 2005, Bocchetta et al 2007) were carried out with solutions containing ≥30 g l −1 Nafion in solvents containing ≥50% water and <15% IPA, Nafion molecules must have aggregated to form large particles (>500 nm) (Jiang et al 2001, Zhang et al 2008) and were unlikely to enter 100-200-nm pores. This is also consistent with the aggregation problems during the pore-filling of PTFE membranes described in the previous section.…”

“…These results were attributed to poor substrate wetting by the Nafion water-alcohol solutions, as opposed to very good wetting by the SPS/acetone solution. Bocchetta et al (2007) used prolonged soaking of AAO membranes (pore size, 200 nm) in a commercial Nafion solution; however, pore-filling was mostly next to the AAO membrane surface without significant penetration into the pores. A work based on the same support filled with Nafion solutions (5 and 20 wt.%) under low vacuum (0.1-0.3 atm) offered some interesting results (Rayon et al 2006).…”

Influence of synthesis conditions on the performance of chitosan–Heteropolyacid complexes as membranes for low temperature H2–O2 fuel cell

“…It is obvious that essential requirement for a fuel cell electrolyte is the good chemical and mechanical stability in the fuel cell environment. Previous results obtained with AAM/PTA fuel cell [11] show a strong degradation of the performance due to the dissolution of both the acidic pore-filler and the alumina membrane in the water produced at the cathode/ electrolyte interface. The performance loss decreases for CS/PTA filled AAM and disappears for solution cast CS/PTA film electrolyte which produces a constant 10 mW cm À2 power output for at least 10 h, as reported in our previous work [14].…”

Cerium Oxyhydroxide Nanowire Growth via Electrogeneration of Base in Nonaqueous Electrolytes

“…It has been demonstrated in previous works that porous anodic alumina can be successfully employed as an ionic conductor support in fuel cells due to their physicochemical properties. 5,6 AAMs have a high thermal stability that prevents the powdering of the ionic conductor with possible gas crossover or short circuit problems. Moreover, alumina membranes show an extremely ordered porous structure with an easy electrochemical control of thickness ͑from a few micrometers to hundreds of micrometers͒, porosity ͑from 10 to 43%͒, and pore diameter ͑20-200 nm͒, which guarantee a highly precise control of the size of the ionic nanowire conductor.…”