A CsCl-type inorganic cluster-based high-symmetry crystal built from {Mo4.55V7.45PO40}10.45- with a high ratio of vanadium to molybdenum and {(H2O)0.3@K6(H2O)12}6+ clusters exhibiting proton conduction below the freezing point of water

Anhydrous Solid-State Proton Conduction in Crystalline MOFs, COFs, HOFs, and POMs

Strategic design of solid-state proton-conducting electrolytes for application in anhydrous proton-exchange membrane fuel cells (PEMFCs) has gained burgeoning interest due to a spectrum of advantageous features, including higher CO tolerance and ease in the water management systems. Toward this direction, crystalline materials like metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), and polyoxometalates (POMs) are emerging PEM materials, offering strategic structural engineering through crystallography, thus enabling ultrahigh anhydrous proton conductivity up to 10-2-10-1 S/cm. This Perspective highlights significant progress achieved thus far with such crystalline platforms in the domain of anhydrous proton conduction across a wide temperature window (sub-zero to above 100 °C). Based on their structural backgrounds, these platforms are categorized into four classes (viz. MOFs, COFs, HOFs, and POMs) with a detailed evolutionary timeline since their emergence early in 2009. Insightful discussions with a key focus on the strategies undertaken to attain anhydrous proton conductivity along with implementation in fuel cell technology through membrane electrode assembly are presented. A section on "Critical Analysis and Future Prospects" provides decisive key viewpoints on those overlooked issues with future endorsement (e.g., performance assessment with CO tolerance analysis and fuel cell test stand) for further development while comparing them with other anhydrous platforms from both academic and industrial perspectives.

Construction of a unique 2-D layered vanadoborate with water-assisted proton conductivity

In the present work, a new two-dimensional layered vanadoborate Na4[V12B18O54(OH)6(H2O)]•(H2en)4•2(OH)•3H2O (1, en = ethylenediamine), based on a [V12B18O54(OH)6(H2O)]10- cluster unit, was hydrothermally obtained and characterized. In the structure, the clusters...

Structure-directing effect of aqueous alkali metal ion (Li+, Na+ and K+) clusters on the polyoxoanion configuration in vanadium–molybdenum polyoxometalate solid solutions

Aqueous alkali metal ion clusters direct the configuration of vanadium–molybdenum solid solution polyoxometalates and crystal structures.