Abstract: Provided is a carbon dioxide recovery system that separates CO2 from a CO2-containing gas containing CO2 by an electrochemical reaction, and comprises an electrochemical cell comprising a working electrode containing a CO2 adsorbent, and a counter electrode. Application of a voltage between the working electrode and the counter electrode causes electrons to be supplied from the counter electrode to the working electrode, and enables the CO2 adsorbent to bind to CO2 as electrons are supplied. The CO2 adsorbent is a crystalline porous body, and has a molecular structure in which a functional group that exchanges electrons and binds to CO2 is regularly arranged.

Abstract: A proton conductor is in contact with a catalyst containing platinum. The proton conductor includes a cationic organic molecule, a metal ion, and an oxoacid anion. A protic ionic liquid containing the cationic organic molecule and the oxoacid anion is coordinated to the metal ion to form a coordination polymer.

Abstract: A proton conductor includes a complex of phosphoric acid and a coordination polymer in which a metal ion and a ligand are continuously connected by a coordinate bond. The phosphoric acid includes a first phosphoric acid that is coordinately bonded to the metal ion, and a second phosphoric acid that is not coordinately bonded to the metal ion.

Abstract: A proton conductor includes a coordination polymer having stoichiometrically metal ions, oxoanions, and proton coordinating molecules capable of undergoing protonation or deprotonation. The coordination polymer including coordination entities that are repeatedly coordinated to bond the coordination entities with one another. Each coordination entity is either a first coordination entity or a second coordination entity. The first coordination entity is one metal ion of the metal ions coordinated with either at least one oxoanion of the oxoanions or at least one proton coordinating molecule of the proton coordinating molecules. The second coordination entity is the metal ion coordinated with each of at least one oxoanion of the oxoanions and at least one proton coordinating molecule of the proton coordinating molecules. At least a part of the proton conductor is non-crystalline. The proton conductor has high ion conductivity at high temperature.

Abstract: A proton conductor includes a metal ion, an oxoanion, and a molecule capable of undergoing protonation or deprotonation, in which at least one of the oxoanion and the molecule capable of undergoing protonation or deprotonation coordinates to the metal ion to form a coordination polymer. The oxoanion is preferably a monomer. The oxoanion is exemplified by at least one selected from the group consisting of phosphate ion, hydrogenphosphate ion, and dihydrogenphosphate ion. The molecule capable of undergoing protonation or deprotonation is exemplified by at least one selected from the group consisting of imidazole, triazole, benzimidazole, benzotriazole, and derivatives thereof.