A Self‐Anchored Phosphotungstic Acid Hybrid Proton Exchange Membrane Achieved via One‐Step Synthesis

Abstract

approach involving fi xing HPW into a polyvinylpyrrolidone (PVP) and polyethersulfones (PES) matrix. A high proton conductivity of 0.066 S cm -1 is achieved at 60 °C with fully hydrated conditions when the HPW content is 30 wt%, which is very competitive with that of Nafi on115 under the same test conditions. Most signifi cantly, the proton conductivity of PES/PVP-HPW is remarkably stable under a continuous fl ow of deionized (DI) water on both sides of the electrolyte membrane for a test period of more than 500 h. A PEMFC single cell based on the PES/PVP-HPW membrane exhibits impressive performance with a maximum power density of 618 mW cm −2 at 50 °C in H 2 /O 2 , and shows no obvious loss within 500 h. This hybrid PES/PVP-HPW holds great potential applications as a novel PEM due to the comparable performance and signifi cantly reduced cost compared to Nafi on.The synthesis and formation of the HPW self-anchored PES/PVP-HPW PEM through a one-step route was given in Scheme 1 . PVP, PES (mass ratio PVP:PES = 90:10) and HPW with desired content (e.g., 10 wt%, 20 wt%, or 30 wt%) were mixed in N , N -dimethylformamide (DMF) and stirred to form a transparent and homogeneous casting solution. This solution was cast onto a glass plate and dried at 343 K for 24 h to remove the solvent and obtain a PES/PVP-HPW. In the hybrid PEM, PVP that contains an N-heterocycle plays a key role in the formation of membrane and offers self-anchored site for HPW. The self-anchored HPW in the membrane acts as the sole proton conductor and cross-linking agent. PES was added to the membrane as a skeleton, to improve membrane formation and enhance the mechanical strength of the hybrid membrane, which could be replaced with other engineering plastics, for example, polysulfone, polyvinylidene fl uoride, or polyarylsulfone. Figure 1 a-c shows a photograph and cross-sectional scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the as-prepared PES/PVP-HPW. The photograph shown in Figure 1 a shows that the membrane was highly transparent and fl exible. The SEM image of the PES/PVP-HPW membrane cross-section exhibited no obvious phase separation, which indicates that these membranes were homogeneous (Figure 1 b). The energy-dispersive X-ray spectroscopy (EDS) tungsten (W) map (inset of Figure 1 b) indicates that the element W (green spots) was homogeneously dispersed in the membrane, which was further demonstrated by the TEM image of the hybrid membrane (Figure 1 c). The average HPW nanoparticle size was determined to be ca. 2.2 nm with a narrow distribution (Supporting Information Figure S1), which was about two HPW molecule size. [ 8 ] The X-ray diffraction (XRD) patterns of the hybrid membrane (see Supporting Information Figure S2) contained no characteristic diffraction peaks The development of proton exchange membranes (PEMs) with improved performance is critical for advancing electrochemical energy devices such as fuel cells and water electrolyzers. [ 1 ] However, the large-scale application of state-of...

Proton exchange nanohybrid membranes with high phosphotungstic acid loading within metal-organic frameworks for PEMFC applications

“…However, due to the high water solubility, the leakage of phosphotungstic acid is serious [22]. Researchers have made great efforts to prevent the loss of phosphotungstic acid by anchoring it into polymer matrix through coordination interaction [17,23] or immobilizing it on supporters [24,27].…”

Magnetic field alignment of stable proton-conducting channels in an electrolyte membrane

“…Other approaches involve immobilization of PWA onto water-insoluble supports, such as SiO 2 29,30 , ZrO 2 31,32 , mesoporous silica 33,34 , and carbon nanotube 35 . More recently, amino-containing polymers, stabilized PWAs by hydrogen bonding 36 , electrostatic force 37,38 , or acid–base interactions 36,39 have been reported, as well as chemical bonding of lacunary silicotungstic acid (SiWA, similar to PWA) to polymers 40–42 . With these approaches, enhanced stability of PWA composite PEMs was achieved, but long-term membrane stability tests (>30 days) under severe conditions (>90 °C in water) are not reported.…”

Ion-Exchange-Induced Selective Etching for the Synthesis of Amino-Functionalized Hollow Mesoporous Silica for Elevated-High-Temperature Fuel Cells

“…S5). [38][39][40] The slightly lower ; (E) the corresponding 29 Si MAS NMR spectra and (F) quantitative 29 Si MAS NMR analysis for the products. The CTAB surfactant in the final products was removed by a reflux treatment in EtOH/HCl at 80 °C for 3h.…”