Effect of the exposure time of hydrazine vapor on the reduction of graphene oxide films.

Preparation of highly uniform graphene with superior electrical properties is one of the key issues in graphene researches. The use of hydrazine vapor for reducing the graphene oxide (GO) has attracted considerable attention in recent year due to the simplicity, reproduciblilty and availibility of one-step procedure. Here, we investigated the effect of the exposure time of hydrazine vapor on the reduction of GO films. Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectrophotometer, and X-ray diffraction results showed that the reduction rate of the GO films by hydrazine vapor was very fast in the initial 10 min, and thereafter the reduction rate slowed down. Upon 12 hours of hydrazine vapor treatment, the reduction came to a level that further hydrazine vapor treatment did not bring about significant improvement of the reduction. We demonstrated that this might be attributed to the slow penetration of hydrazine vapor into the GO films in order to reduce the inner sheets of the GO films.