Hierarchical Nanostructured WO3with BiomimeticProton Channels and Mixed Ionic-Electronic Conductivity for ElectrochemicalEnergy Storage.

Protein channels in biologic systemscan effectively transport ions such as proton (H+), sodium(Na+), and calcium (Ca+) ions. However, noneof such channels is able to conduct electrons. Inspired by the biologicproton channels, we report a novel hierarchical nanostructured hydroushexagonal WO3(h-WO3) whichcan conduct both protons and electrons. This mixed protonic–electronicconductor (MPEC) can be synthesized by a facile single-step hydrothermalreaction at low temperature, which results in a three-dimensionalnanostructure self-assembled from h-WO3nanorods. Such a unique h-WO3containsbiomimetic proton channels where single-file water chains embeddedwithin the electron-conducting matrix, which is critical for fastelectrokinetics. The mixed conductivities, high redox capacitance,and structural robustness afford the h-WO3with unprecedented electrochemical performance, including high capacitance,fast charge/discharge capability, and very long cycling life (>50 000cycles without capacitance decay), thus providing a new platform fora broad range of applications. [ABSTRACT FROM AUTHOR]