title: Simultaneous Nitrogen Doping and Pore Generation in Thermo-Insulating Graphene Films via Colloidal Templating.
abstract: We report a simple method for preparing highly efficient thermoelectric materials through the fabrication of nitrogen-doped reduced graphene oxide (GO) with a porous structure. The samples were produced by thermal annealing of GO/nitrogen-rich polystyrene (N-PS) particle composite films using a colloidal templating method. N-PS particles served as a nitrogen dopant source for the nitrogen-doped thermally reduced graphene oxide (TrGO) as well as sacrificial particles for the porous structure. The S values of the porous TrGO films were negative, indicating that the samples were transformed into n-type materials. Their porous structures simultaneously resulted in materials with high σ values and low in-plane κ values by providing numerous air cavities for phonon scattering and destruction of the anisotropic structure, maintaining an interconnected structure for an electron transport path. Thus, the porous TrGO films exhibited enhanced power factors and low κ values. The highest ZT value of 1.39 × 10-4was attained for a porous TrGO film annealed at 1100 °C, which was 1200 times higher than that of a nonporous TrGO film. This study emphasizes that an isotropic orientation of two-dimensional materials has a significant effect on the suppression of in-plane κ, leading to their enhanced thermoelectric performance.
authors: School of Advanced Materials Engineering, Kookmin University , 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Republic of Korea.
authors: Hyunwoo
authors: H
authors: Bark
authors: School of Advanced Materials Engineering, Kookmin University , 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Republic of Korea.
authors: Jeongmin
authors: J
authors: Lee
authors: Electronic Materials & Device Research Center, Korea Electronics Technology Institute , 25 Saenariro, Bundanggu, Seongnamsi, Gyeonggido 463-816, Republic of Korea.
authors: Hosun
authors: H
authors: Lim
authors: Korea Institute of Science and Technology , 92 Chudong-ro, Bongdong-eup, Wanju-gun, Jeollabuk-do 565-905, Republic of Korea.
authors: Hye Young
authors: HY
authors: Koo
authors: Department of Chemistry, Sejong University , 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747, Republic of Korea.
authors: Wonmok
authors: W
authors: Lee
authors: School of Advanced Materials Engineering, Kookmin University , 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Republic of Korea.
authors: Hyunjung
authors: H
authors: Lee
keywords: ZT; colloidal templating; nitrogen doping; porous structure; reduced graphene oxide