A facile fabrication of n-type Bi2Te3 nanowire/graphene layer-by-layer hybrid structures and their improved thermoelectric performance

• n-Type Bi2Te3 nanowire/graphene layer-by-layer composites are fabricated.
• Synthesized composite films show high thermoelectric performance.
• Bi2Te3 nanowires contribute to the increase in Seebeck coefficient of the composite.
• Phonons are significantly scattered at the interfaces between nanowires and graphene.

n-Type Bi2Te3 nanowire/graphene composite films were prepared with a facile wet chemical synthesis and sintering process, and the effect of Bi2Te3 nanowire content on the thermoelectric properties of the composite films were investigated. The one-dimensional Bi2Te3 nanowires were homogeneously intercalated and dispersed between the prepared graphene layers, forming the Bi2Te3 nanowire/graphene layer-by-layer hybrid structure. These composite films showed enhanced thermoelectric properties compared to the pristine graphene film fabricated with the same methods but without the Bi2Te3 nanowires. This was attributed to both the large Seebeck coefficient, which is intrinsic to the Bi2Te3 nanowires, and the reduced thermal conductivity, which is attributed to the exceptional phonon scattering at the interfaces between the nanowires and graphene layers. The maximum thermoelectric efficiency (ZT) of the Bi2Te3 nanowire/graphene composites was achieved with a Bi2Te3 nanowire content of 20 wt.%. This composite had a dramatically improved ZT value of 0.2, which was ∼27 times larger than that of the pristine graphene film.

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