Encapsulating Mobile Proton Carriers into Structural Defects in Coordination Polymer Crystals: High Anhydrous Proton Conduction and Fuel Cell Application

Abstract

We describe the encapsulation of mobile proton carriers into defect sites in nonporous coordination polymers (CPs). The proton carriers were encapsulated with high mobility and provided high proton conductivity at 150 °C under anhydrous conditions. The high proton conductivity and nonporous nature of the CP allowed its application as an electrolyte in a fuel cell. The defects and mobile proton carriers were investigated using solid-state NMR, XAFS, XRD, and ICP-AES/EA. On the basis of these analyses, we concluded that the defect sites provide space for mobile uncoordinated H3PO4, H2PO4(-), and H2O. These mobile carriers play a key role in expanding the proton-hopping path and promoting the mobility of protons in the coordination framework, leading to high proton conductivity and fuel cell power generation.

Arrangement of water molecules and high proton conductivity of tunnel structure phosphates, KMg1−xH2x(PO3)3·yH2O

“…Proton conduction is an essential phenomenon common in the metabolism of biological systems [1][2][3] and the operation of electrochemical devices such as fuel cells. [4][5][6][7][8][9] An understanding of proton conduction and the development of fast proton conductors are important for material science, chemistry, and biology due to fundamental interests and potential applications. Fast proton conduction in solids has been achieved by the design of proton conduction pathways in their crystal structures.…”

Metal–Organic Frameworks as a Versatile Platform for Proton Conductors

“…In particularly, ZrP can be used directly as the electrolyte for intermediate‐temperature PEMFC, affording a record‐high peak power density of 12 mW cm −2 at 180 °C (Figure 20d,e), which is over four times larger than those of representative CP‐based PEMFCs. [ 150,151 ] Furthermore, they also employed the ZrP for the first time as solid‐state electrolyte for assembling the direct methanol fuel cell (DMFC). This study shows a step forward toward the actual application of CP/MOF as solid electrolyte for fuel cells.…”

Dicarboxylate‐Induced Structural Diversity of Luminescent Zn(II)/Cd(II) Metal–Organic Frameworks Based on the 2,5‐Bis(4‐pyridyl)thiazolo[5,4‐d]thiazole Ligand

“…As a kind of distinctive ordered porous materials, metal‐organic frameworks (MOFs) have attracted considerable attention in the past decades. Apart from their intriguing structures, the interesting properties of MOFs impart various potential applications, such as gas adsorption and separation, hazardous substance adsorption and removal, proton conduction, chemical sensor, photoluminescence, and so on. Recently, photoluminescence properties of MOFs have become one of the research hotspots .…”