The influence of residual oxidizing impurities on the synthesis of graphene by atmospheric pressure chemical vapor deposition

TL;DR

This study investigates how residual oxidizing impurities affect graphene growth via atmospheric pressure chemical vapor deposition, emphasizing the critical role of hydrogen in achieving high-quality graphene in a vacuum-free system.

Contribution

It demonstrates that hydrogen presence during growth and cooling is essential to prevent oxidation and produce high-quality graphene in a system without vacuum equipment.

Findings

Hydrogen is necessary during growth for high-quality graphene.

Fast cooling or hydrogen flow preserves graphene from oxidation.

Residual oxidants cause oxidized and amorphous carbon coverage.

Abstract

The growth of graphene on copper by atmospheric pressure chemical vapor deposition in a system free of pumping equipment is investigated. The emphasis is put on the necessity of hydrogen presence during graphene synthesis and cooling. In the absence of hydrogen during the growth step or cooling at slow rate, weak carbon coverage, consisting mostly of oxidized and amorphous carbon, is obtained on the copper catalyst. The oxidation originates from the inevitable occurrence of residual oxidizing impurities in the reactor's atmosphere. Graphene with appreciable coverage can be grown within the vacuum-free furnace only upon admitting hydrogen during the growth step. After formation, it is preserved from the destructive effect of residual oxidizing contaminants once exposure at high temperature is minimized by fast cooling or hydrogen flow. Under these conditions, micrometer-sized hexagon-shaped graphene domains of high structural quality are achieved.