Graphene-Based Composites for Thermoelectric Applications at Room Temperature

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Developing room-temperature thermoelectric materials is challenging due to the need to optimize electrical conductivity, thermal conductivity, and Seebeck coefficient.
• Hybrid composites offer a strategy to tune thermoelectric properties by combining different material types.

Purpose of the Study:

• To explore the formation of hybrid composites between graphene-based materials and oxides.
• To modify and enhance thermoelectric performance at room temperature.

Main Methods:

• Selected graphene materials: N-containing reduced graphene oxide (NrGO) and expanded graphite (ExGr).
• Selected oxides: p-type Ca3Co4O9 and n-type Zn0.995Al0.005O.
• Hybrid composites prepared via mechanical milling and pelleting.
• Thermoelectric efficiency evaluated by measuring electrical resistivity, Seebeck coefficient, and thermal conductivity at room temperature.

Main Results:

• 2 wt.% of ExGr or NrGO enhanced the thermoelectric activity of Ca3Co4O9.
• For Zn0.995Al0.005O, optimal ExGr content ranged from 5 to 20 wt.% for enhanced thermoelectric properties.
• SEM/EDS experiments provided insights into the effect of composite morphology on thermoelectric properties.

Conclusions:

• Hybrid composites of graphene-based materials and oxides show potential for improved room-temperature thermoelectric performance.
• Specific compositions and weight percentages of ExGr and NrGO significantly influence the thermoelectric efficiency of Ca3Co4O9 and Zn0.995Al0.005O.
• The study highlights the role of material morphology in optimizing thermoelectric properties.