Enhanced thermoelectric performance of Bi₂Te_2.7Se_0.3 by texturing and decoration of activated carbon via shear-exfoliation

In the present work, activated carbon (AC) was used to prepare a series of Bi₂Te_2.7Se_0.3-AC nanocomposites through a liquid-assisted shear-exfoliation (LASE) process and the effects on microstructure and thermoelectric transport properties were investigated. Textured and grain-refined microstructure was developed in the LASE-derived composite bulks. A stepped increment of carrier mobility and mobility was observed via LASE and the AC decoration, enabling an optimal high-power factor of ∼25 μW cm⁻¹ K⁻² at 303 K. Notably, the lattice thermal conductivity was reduced effectively by LASE and further by AC decoration due to strengthened grain-refinement and interfacial phonon scattering. Ultimately, due to the electron-emitting and phonon-blocking effect of AC, a maximal ZT value of 1.01 at 423 K was realized in the Bi₂Te_2.7Se_0.3-0.05 mol% AC composite, which is almost double that for the non-LASE pristine sample.