Transport studies of two-step synthesized Cu2Se-Graphene nanocomposites

Abstract

Copper Selenide (Cu2Se), in recent times, rated among the most potential thermoelectric materials, backing its excellent intrinsic thermoelectric (TE) performance arising from the unique nature of Cu + ions behaving like a liquid. Here we present experimental findings of Cu2Se-carbon nanostructure (graphene) composited in which Cu2Se has been synthesized using a cost-effective chemical reduction method, and graphene was incorporated in the Cu2Se matrix by simple mechanical grinding. The TE characteristics of graphene distributed at various weight percentages (0.5, 1, 2, 4, and 5 wt%) in the Cu2Se matrix are presented. The electrical conductivity and power factor of the sample at 450 °C temperature were dramatically improved by adding 1 wt% graphene to the Cu2Se matrix. All samples have been analyzed extensively by Field Emission Scanning Electron Microscopy, X-ray diffraction, High-Resolution Transmission Electron Microscopy, Raman, TE properties measurements, etc. Graphene was discovered to be densely and uniformly spread within the Cu2Se matrix material, resulting in a secondary phase of graphene/Cu2Se interfaces. Although there are minimal changes in the Seebeck coefficient, the power factor improved significantly because of the enhancement in electrical conductivity by the incorporation of graphene. The power factor in 1 wt% graphene incorporated Cu2Se enhanced to 1250 μW/mK2 at 450 °C compared to the power factor of 585 μW/mK2 for the bare Cu2Se sample. The purpose of this study is to determine the optimum graphene percentage that gives better performance.