Enhancing proton conductivity in a metal–organic framework at T > 80 °C by an anchoring strategy

Abstract

A new Zr(IV)-based metal–organic framework, termed VNU-23 [Zr₆O₈(H₂O)₈(H₂SNDC)₄], where H₂SNDC²⁻ = 4,8-disulfonaphthalene-2,6-dicarboxylate, was synthesized. Subsequently, detailed structural analysis revealed that VNU-23 adopted the bcu topology with a structure characterized by densely packed sulfonic acid groups lining 6 Å channels. With this structural feature, an anchoring strategy was employed to dock the proton transfer agent, histamine, into the void space of VNU-23 to enhance the proton conductivity. Remarkably, the proton conductivity of this material reached 1.79 × 10⁻² S cm⁻¹ at 95 °C and 85% relative humidity without any appreciable loss of performance for at least 120 h.