Computational Exploration of the Water Concentration Dependence of the Proton Transport in the Porous UiO-66(Zr)-(CO2H)(2) Metal-Organic Framework

Author(s)

Borges, Daiane Damasceno ; Semino, Rocio ; Devautour-Vinott, Sabine ; Jobic, Herve ; Paesani, Francesco ; Maurin, Guillaume

• Document type: Journal article
• Source: CHEMISTRY OF MATERIALS; v. 29, n. 4, p. 8-pg., 2017-02-28.

Abstract

The UiO-66(Zr)-(CO2H)(2) metal-organic framework been recently revealed as a promising proton conducting material under humidification. Here, aMS-EVB3 molecular dynamics simulations are performed to reveal at the molecular level the structure, thermodynamics, and dynamics of the hydrated proton in three-dimensional (3D)-cages MOF as a function of the water loading. It is found that the most stable proton solvation structure corresponds to a H7O3+ cation and that a transition between this complex and a Zundel cation likely governs the proton transport in this MOF occurring via a Grotthuss-type mechanism. It is further shown that the formation of a H2O hydrogen-bonded bridge that connects the cages occurs only at high water concentration and this creates a path allowing the excess proton to jump from one cage to another. This leads to a faster self-diffusivity of proton at high water concentration, thereby supporting the increase of the proton conductivity with the water loading as experimentally evidenced. (AU)

• FAPESP's process: 15/14703-9 - Theoretical study on the structural and mechanical properties of MOFs (metal-organic frameworks)
• Grantee: Daiane Damasceno Borges
• Support Opportunities: Scholarships in Brazil - Post-Doctoral