A highly reduced Mo74 polyoxometalate featuring high proton conductivity accessed by building block strategy

Highly reduced polyoxometalates (POMs) are predicted to be used as rather high energy density materials; however, it still suffers from the limited cluster species and reduction ratio. Here we demonstrate that it is possible to employ the building block strategy to generate a highly reduced polyoxomolybdate (C2H8N)(14)(NH4)(4)H-14[(Mo48Mo26O202)-Mo-V-O-VI(OH)(12)(SO4)(6)]46H(2)O (Mo-74). The fundamental Mo-based {Mo-x} (x = 4, 5, and 6) building blocks, which are templated by tetra-coordinated anions {MoO4} or, not only lay foundation for the formation of Mo-74 featuring an unprecedented reduction ratio of 65%, but also give rise to SBBs-mediated (secondary building blocks) supramolecular dense packing interactions among the isolated Mo-74 clusters that are favorable for proton conduction. Remarkably, high proton conductivity (2.04 x 10(-2) S cm(-1)) had been realized at 50 degrees C and 90% relative humidity, revealing one of the well-known POMs-based crystalline proton conducting materials. This result highlights that this building block approach possesses great potential in producing highly reduced POM systems that can achieve controllable reduced ratio and desirable properties.

Automated summary

The building block strategy is demonstrated to be capable of generating highly reduced polyoxometalates with desirable properties, such as high proton conductivity.