CsH₂PO₄/NdPO₄Composites as Proton Conducting Electrolytes for Intermediate Temperature Fuel Cells

Abstract

Composite proton conducting materials based on cesium dihydrogen phosphate and neodymium phosphate hydrate were prepared and investigated in terms of X-ray diffraction, thermogravimetry, conductivity, stability and fuel cell performance. At 150 • C the conductivity was 1.8 × 10 −6 S cm −1 for the pristine cesium dihydrogen phosphate and 0.8 × 10 −4 S cm −1 for neodymium phosphate hydrate, while that of the composite containing 29 mol% neodymium phosphate and 71 mol% cesium dihydrogen phosphate was 0.4 × 10 −2 S cm −1 . It was proposed that the interaction between the two components establishes a dynamic hydrogen bonding network enabling efficient proton conduction long before the development of the extensive phase disordering of the superprotonic transition. The presence of thermally stable hydrate water present in neodymium phosphate may also play a role in improving both conductivity and stability of the solid acid. The electromotive force, open circuit voltage and fuel cell performance were measured as demonstration of the material application.

Crystallization Pathways of Cerium(IV) Phosphates Under Hydrothermal Conditions: A Search for New Phases with a Tunnel Structure

“…Crystalline rare‐earth phosphates are widely used in high‐tech industrial applications such as for optical materials, heat‐resistant ceramics, ion‐exchange materials, luminophores and as radioactive waste sorbents . Cerium phosphates are of particular interest since they can contain cerium ions in both +3 and +4 oxidation states.…”

Effects of La2O3, CeO2 and LaPO4 introduction on vanadium tolerance of USY zeolites

“…As a very stable compound with high melting point [30,31], lanthanum orthophosphate LaPO 4 does not affect the properties of catalysts. The phosphorous compounds which afford the best results for the direct applications of immobilizing the vanadium in the catalytic cracking catalyst [32].…”

“…Furthermore, the introduced rare earth metals exchanged in the Y zeolite and affected the product distribution by changing the hydrogen transfer of catalysts [41,42], which was unexpected because the rare earth species functioned as vanadium traps. Vanadium is held immovable by phosphorus compounds in the form of stable V 4+ and V 5+ compounds [31,43], and the redox reaction between phosphorus compounds and V 2 O 5 has never been reported hitherto. The mechanism is different from that of the reaction between alkaline active component and acid vanadium oxide, and the negative reaction between acid oxysulfide in industrial reactors and alkaline vanadium-trapping substance can be circumvented.…”

Simultaneous improvement of ionic conductivity and oxidative stability of sulfonated poly(ether ether ketone) nanocomposite proton exchange membrane for fuel cell application

“…The approach in the second category is making nanocomposite membranes with the aid of some functional nanomaterials, which induces the unique properties into the matrix of the membrane such as hygroscopicity, restricting the fuel crossover, increasing the thermal and mechanical tolerance, and radical scavenging . The introduction of some of these inorganics like metal/metal oxides, carbon‐based nanomaterials, nanoclays, and solid proton conductors (eg, heteropolyacids, super‐acids, and layered metal phosphates) into the SPEEK polymer matrix and their effects were extensively studied. Metal oxide nanomaterials are more promising fillers that have recently attracted an increasing research interest toward fuel cell applications because of their hygroscopic nature besides the proton conductivity of acidic sites .…”