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

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 20wt.%. This composite had a dramatically improved ZT value of 0.2, which was ~27 times larger than that of the pristine graphene film.