Ionic Thermoelectric Properties of Reconstructed Lamellar Vanadium Pentoxide Membranes

In recent years, the application of ionic thermoelectric (TE) materials to convert low-grade waste heat into electricity has become a subject of intense scientific research. However, most of the efforts are focused on organic polyelectrolytes or ionic-liquids embedded in polymeric gels. Here, for the first time, it is demonstrated that nanofluidic membranes of reconstructed layered materials like vanadium pentoxide (V₂O₅) exhibit excellent ionic-TE characteristics. The high Seebeck coefficient (S = 14.5 ± 0.5 mV K^-1) of the V₂O₅ membrane (VO-M) is attributed to temperature gradient-induced unidirectional transport of protons through the percolated network of 2D nanofluidic channels. The TE characteristics of VO-M show nearly 80% improvement (S = 26.3 ± 0.7 mV K^-1) upon functionalizing its percolated network with ionic polymers like poly(4-styrenesulfonic acid) (PSS). Further, unlike organic polymer-based TE systems, VO-M not only sustains exposure to high temperatures (≈200 °C, 5 min) but also protects the PSS molecules intercalated into its interlayer space. Moreover, V₂O₅-based TE materials can self-repair any damage to their physical structure with the help of a tiny water droplet. Thus, nanofluidic membranes of reconstructed layered materials like VO-Ms demonstrate vast robustness and great ionic-TE performance, which can provide a novel platform for scientific studies and futuristic applications.