Two 2D Layered P₄Mo₆ Clusters with Potential Bifunctional Properties: Proton Conduction and CO₂ Photoreduction

Abstract

Two hourglass-type molybdophosphate hybrids with the formulas [Cd(H2O)2DABT]4[Cd(H7P4Mo6O31)2]·19H2O (1) and (C2H5OH)(C3H5N2)6[Co3(H6P4Mo6O31)2]·H2O (2) (DABT= 3,3′-diamino-5,5′-bis(1H-1,2,4-triazole)) have been successfully designed and synthesized via a hydrothermal method. Structure analysis revealed that the inorganic moieties in compounds 1 and 2 are made up of hourglass-type {M[P4Mo6]2} (M = Cd/Co) structure, which were constructed by two (P4Mo6) units with single transition metal (TM) (Cd/Co) atom as the central metal. The {M[P4Mo6]2} (M = Cd/Co) structures were then further connected by TM to constitute a 2D layered structure. Surprisingly, under the condition of 60 °C and 98% RH, compounds 1 and 2 exhibited excellent proton conductivity of 1.35 × 10–3 and 3.78 × 10–3 S cm–1, respectively. Furthermore, compound 2 can act as heterogeneous catalyst for CO2 photoreduction, which indicates that it may be a bifunctional POM-based material with great promise.