Realizing high thermoelectric performance in MXene-incorporated Yb0.4Co3.96Ti0.04Sb12via carrier and phonon engineering

Abstract

The secondary nanostructures embedded to the matrix phase have shown up as a promising route of developing highly efficient TE materials which refers to the blockage of low energy charge carriers while transmitting only the high energy charge carriers leading to improvisation of both Seebeck coefficient and electrical conductivity. Herein, we demonstrate the enhanced thermoelectric performance in a 2-D layered Ti₃C₂T_x MXene-embedded Yb_0.4Co_3.96Ti_0.04Sb₁₂ matrix attained via carrier engineering using energy filtering and phonon engineering by anharmonicity and interface scattering. The addition of (y wt%) Ti₃C₂T_x in n-type Yb_0.4Co_3.96Ti_0.04Sb₁₂ introduced hole carriers and thereby reduced the carrier concentration (n_e) from ∼2.50 × 10²⁰ cm⁻³ for y = 0 to ∼1.6 × 10²⁰ cm⁻³ for y = 0.50. Interestingly, owing to strong phonon scattering across the potential barrier built at Ti₃C₂T_x/Yb_0.4Co_3.96Ti_0.04Sb₁₂ interfaces, the total thermal conductivity κ_total was significantly reduced to ∼1.37 W m⁻¹ K⁻¹ at 616 K for y = 0.50. Furthermore, the carrier-filtering facilitated the large Seebeck coefficient of −208 μV K⁻¹ at 665 K, which resulted in the enhanced zT value of ∼0.93 at 616 K for 0.50 wt% Ti₃C₂T_x/Yb_0.4Co_3.96Ti_0.04Sb₁₂. Additionally, the maximum theoretical thermoelectric conversion efficiency (η_max) was calculated to be ∼7% for a temperature difference of 450 K, leading to the development of a potential n-type candidate for practical device applications, and thus, the incorporation of Ti₃C₂T_x-based materials provides a pathway to enhance the thermoelectric performance.