Constructing n-type Ag2Se/CNTs composites toward synergistically enhanced thermoelectric and mechanical performance

Silver selenide (Ag2Se) is emerging as an intriguing material for thermoelectric refrigeration and energy harvesting at near room temperature. To promote the practical applications of Ag2Se, it is imperative to further depress its lattice thermal conductivity (κL) and enhance its mechanical properties. Herein, we develop a nanocompositing strategy toward both enhanced thermoelectric and mechanical performance. Through in situ solution synthesis combined with fast sintering, a series of Ag2Se/carbon nanotubes (CNTs) nanocomposites are controllably constructed. Tuning the concentration of CNTs effectively optimizes the transport and mechanical properties simultaneously, with 0.5 wt% as the optimized addition amount: (i) due to the interfacial effects, this optimal sample obtains a substantially low κL of 0.27 W m–1 K–1 and a slightly enhanced power factor of 2.71 mW m–1 K–2 at 375 K, leading to an exceptional peak zT of 0.97 at 375 K and a high average zT of ∼0.89 over 300–375 K; (ii) this composite achieves a yield strength of 76.0 MPa and a compressive strength of 99.5 MPa, which are improved by 77.2% and 13.3% compared to pristine Ag2Se, respectively. This study develops an effective strategy to construct Ag2Se/CNTs nanocomposites, which advances both thermoelectric and mechanical performance.