Effect of the reduction process on the field emission performance of reduced graphene oxide cathodes

TL;DR

This study compares how different reduction methods affect the field emission performance of reduced graphene oxide cathodes, finding that thermal reduction yields the best electron emission properties.

Contribution

It provides a comparative analysis of chemical and thermal reduction techniques on rGO cathodes, linking reduction methods to emission performance and lattice characteristics.

Findings

Thermal reduction produces the lowest turn-on field (~1.8 V/mm) and highest field enhancement (~1300).

Different reduction methods lead to distinct lattice parameters and work functions.

KOH reduction results in the poorest field emission performance.

Abstract

The electron field emission (FE) properties of reduced graphene oxide (rGO) cathodes produced by three different reduction methods were assessed and compared. In particular, chemical reduction techniques, using either NaOH or KOH as reducing agents, were compared with thermal reduction (TR) methods. Xray photoelectron spectroscopy (XPS) measurements revealed that different reduction techniques led to different GO lattice parameters. Furthermore, the work function measured with ultraviolet photoelectron spectroscopy (UPS) varied among the samples giving rise to different electron emission characteristics. In particular, the cathodes prepared by the TR method presented the best FE performance, showing a turnon field of as low as ca. 1.8 V mm^-1 and a field enhancement factor of ca. 1300, which was very close however to that shown by the NaOH-reduced sheets. The worst FE properties were exhibited by the KOH-reduced nanosheets. In light of the above results, the role of the different reduction techniques as well as the final rGO lattice characteristics with regards to the emission performance are evaluated and discussed.