Graphene reduction dynamics unveiled

The reduction dynamics of micron-sized defects created on chemical vapor deposition- (CVD) grown graphene through scanning probe lithography (SPL) is reported here. CVD-grown graphene was locally oxidized using SPL and subsequently reduced, making use of a focused beam of soft x-rays. During this whole process, the reduction dynamics was monitored using a combination of micro-Raman spectroscopy (μ-RS) and micro-x-ray photoelectron spectroscopy (μ-XPS). After x-ray reduction, the graphene film was found to be chemically identical (μ-XPS) but structurally different (μ-RS) from the original graphene. During reduction the population of C–C bonds was found to first increase dramatically and then decrease exponentially. By modeling the dynamics of the C=O → C–O → C–C → C=C reduction process with four coupled-rate equations and three rate constants, the conversion from C–C to C=C bonds was found to be the limiting rate.