Effect of subphase pH on Langmuir-Blodgett deposition of graphene oxide monolayers on Si and SiO2/Si substrates

Graphene oxide monolayers were transferred onto Si and SiO2/Si substrates by Langmuir-Blodgett technique. Effect of subphase pH changes on the GO Langmuir isotherm and the morphology of monolayers deposited on RCA-1 treated and untreated Si and SiO2/Si substrates is reported. No GO transfer was observed on untreated Si substrate but well defined GO sheets could be transferred at subphase pH ∼ 5.5 on RCA-1 treated Si. GO sheets transferred on untreated SiO2/Si surface exhibit curled up edges, implying poor adhesion. Adherent GO sheets with planar morphology were transferred on RCA-1 treated SiO2/Si substrates at all subphase pH values in the range 3.5-6.5.