A Comparative Investigation of Chemically Reduced Graphene Oxide Thin Films Deposited via Spray Pyrolysis

We present a comparative investigation between thin films of graphene oxide (GO) and chemically reduced graphene oxide (rGO) deposited onto glass substrates via spray pyrolysis. Two reduction techniques are investigated: (1) the exposition of a sprayed layer of GO to vapors of hydrazine hydrate to produce rGOV and (2) the addition of liquid hydrazine hydrate to a suspended GO solution, which is then sprayed onto a substrate to produce rGOL. Three different spectroscopy techniques, Raman, Fourier transform infrared, and UV-Vis-NIR, show that the two reduced samples have less lattice disorder in comparison to GO, with rGOL having the highest degree of reduction. Interestingly, topography characterization by atomic force microscopy reveals a morphological change occurring during the exposure to hydrazine hydrate vapors, resulting in a thickness of 110 nm for the rGOV film, which is a factor of 16 larger than rGOL and GO. Finally, I-V measurements show a significant decrease of the GO's resistivity after the reduction process, where rGOL features a resistivity 90 times lower than rGOV, confirming that rGOL has the highest degree of reduction. Our results indicate that the reduction process for rGOV is susceptible to introducing intercalated water molecules in the material while the fabrication technique for rGOL is a suitable route to obtain a material with minimal lattice disorder and properties approaching those of graphene.