Linear control of the oxidation level on graphene oxide sheets using the cyclic atomic layer reduction technique.

Precise control of the oxidation level on graphene oxide (GO) sheets is still a big challenge. This work demonstrates a linear control of the surface oxidation level on GO sheets via an atomic layer reduction (ALR) technique at 100 and 150 °C. The oxygen stripping rate during ALR cycling was assessed at different operating temperatures: 0.055% per cycle (150 °C) and 0.028% per cycle (100 °C). It was shown that the optical band gap and the electrical conductivity can be linearly tuned by the ALR cycle number for graphene-like materials. This unique capability was not feasible when employing conventional synthesis routes (e.g. thermal or chemical reduction) since these techniques only provide a stepwise control over the oxidation/reduction processes. The in situ oxidation level on GO materials can be accurately controlled through the ALR/atomic layer oxidation (ALO) cycle. Accordingly, the ALR/ALO cycle offers excellent reversibility for adjusting the chemical composition of graphene-like materials and tuning the optical and electronic properties of such nanomaterials.