An Approach to an Ideal Molecule-Based Mixed Conductor with Comparable Proton and Electron Conductivity br

We synthesized a molecule-based proton-electron mixed conductor (PEMC), a Pt(III) dithiolate complex with 1,4-naphthoquinoneskeletons. The pi-planar Pt complex involves a pi-stacking column, which is connected by one-dimensional hydrogen bonding chains composed of water molecules. The room-temperature (RT) proton conductivity is 8.0x10-5Scm-1under ambient conditions, which is >2 orders of magnitude higher than that of the isomorphous Ni complex (7.2x10-7Scm-1). The smaller activation energy (0.23 eV) compared to that of the Ni complex (0.42 eV)possibly originates from the less dense water, which promotes there orientation al dynamics, in the Pt complex with an expanded lattice, namely, negative chemical pressure upon substitution of Ni with the larger Pt. In addition, the Pt complex shows a relatively high RT electronic conductivity of 1.0x10-3Scm-1caused by the pi-columns, approaching an ideal PEMC with comparable proton and electron conduction.