Performance of H2-fed fuel cell with chitosan/silicotungstic acid membrane as proton conductor

Abstract

Composite organic-inorganic proton exchange membranes for H 2 -O 2 fuel cells were fabricated by ionotropic gelation process combining a biopolymer (chitosan) with a heteropolyacid (silicotungstic acid). According to scanning electron microscopy analysis, compact, homogeneous and free-standing thin layers were synthesized. X-ray diffraction proved the crystallinity of the fabricated membranes and showed the presence of Chitosan Form I polymorph soon after the reticulation step and of the Form II polymorph after the functionalization step. Fourier-transform infrared spectroscopy demonstrated that the Keggin structure of the heteropolyacid is maintained inside the membrane even after the fabrication process. These membranes worked properly as proton conductors in a low-temperature (25 °C) fuel cell apparatus using hydrogen as fuel recording a promising power density peak of 268 mW cm −2 with a Pt loading of 0.5 mg cm −2 .

Effect of TiO2 and Al2O3 Addition on the Performance of Chitosan/Phosphotungstic Composite Membranes for Direct Methanol Fuel Cells

“…Membranes were synthesized by ionotropic gelation process on an anodic alumina membrane (AAM) employed as porous support that was previously impregnated by PTA, as described elsewhere [ 19 , 23 ]. CS solution was prepared by mixing CS powder (2% w / v ), acetic acid (2% w / v ) and distilled water to obtain protonation and solubilization of CS.…”

“…In fact, HPAs suffer from leaching when used as solid electrolytes in FCs’ applications, leading to poor durability. Phosphotungstic acid (PTA) is one of the HPAs that were successfully employed to form composite CS/HPA membranes to be used as proton exchange membranes in hydrogen-fed FCs [ 19 , 20 , 21 , 22 , 23 ] and in DMFCs. In particular, CS/PTA membranes have been successfully tested as proton exchange membranes, reaching high performances at 70 °C with relatively low catalyst loadings at both anode and cathode [ 24 ].…”

Biopolymers‐Based Proton Exchange Membranes For Fuel Cell Applications: A Comprehensive Review

“…Following the work of Pecoraro and Santamaria in further attempts to improve fuel cell performance, Di Franco et al [50] have followed the same process (i. e., ionotropic gelation) to associate chitosan with silicotungstic acid. Different silicotungstic acid functionalization times (12 h and 24 h) and different reticulation times (30s, 10 min, 30 min, 60 min) were set.…”

Methanol and proton transport through chitosan‐phosphotungstic acid membranes for direct methanol fuel cell

“…22 Moreover, CS backbone contains free amine groups that can be protonated, making CS a polycation that can electrostatically interact with polyanions to prepare tailored membranes for fuel cells. 22,23 However, CS suffers from a quite low proton conductivity that can heavily limit its use in DMFCs. Therefore, a commonly exploited strategy to enhance its proton conductivity is the introduction inside CS chains of acids and salts of heteropolyanions.…”

“…As alternative to perfluorinated membranes as Nafion, chitosan (CS) represents one of the most rationale choice in the vast world of proton exchange membrane (PEM) for DMFCs because of a promising low methanol permeability, 19‐21 joined to unique features of hydrophilicity, biocompatibility, biodegradability, and cost‐effectiveness 22 . Moreover, CS backbone contains free amine groups that can be protonated, making CS a polycation that can electrostatically interact with polyanions to prepare tailored membranes for fuel cells 22,23 . However, CS suffers from a quite low proton conductivity that can heavily limit its use in DMFCs.…”