In-situ reduction by Joule heating and measurement of electrical conductivity of graphene oxide in a transmission electron microscope

TL;DR

This study demonstrates in-situ Joule heating in a transmission electron microscope to reduce graphene oxide, enabling simultaneous electrical conductivity measurement and structural analysis, revealing a highly localized reduction process with significant conductivity enhancement.

Contribution

It introduces a novel in-situ TEM method for reducing graphene oxide via Joule heating while measuring its electrical and structural properties simultaneously.

Findings

Conductivity increases over 4 orders of magnitude during reduction.

Reduction starts at a power density of about 2×10^14 W/m^3.

Final oxygen content is less than 1%, indicating effective reduction.

Abstract

Graphene oxide (GO) is reduced by Joule heating using in-situ transmission electron microscopy (TEM). The approach allows the simultaneous study of GO conductivity by electrical measurements and of its composition and structural properties throughout the reduction process by TEM, electron diffraction and electron energy-loss spectroscopy. The small changes of GO properties observed at low applied electric currents are attributed to the promotion of diffusion processes. The actual reduction process starts from an applied power density of about 2 1014 Wm-3 and occurs in a highly uniform and localized manner. The conductivity increases more than 4 orders of magnitude reaching a value of 3 103 Sm-1 with a final O content of less than 1%. We discuss differences between the reduction by thermal annealing and Joule heating.