No Graphene Etching in Purified Hydrogen.

A systematic study has been conducted to investigate the role of hydrogen in the etching reaction of graphene films grown on copper foils. The results at 825 °C and 500 mTorr showed no evidence of graphene etching by purified ultrahigh purity (UHP)-grade hydrogen, whereas graphene films exposed to unpurified UHP-grade hydrogen were considerably etched due to the presence of oxygen or other oxidizing impurities. This finding reveals not only the major impact of oxidizing impurities in the graphene etching reaction, but also entails understanding and controlling the graphene chemical vapor deposition mechanism on copper substrates.