All-Optical and One-Color Rewritable Chemical Patterning on Pristine Graphene under Water

We report a facile all-optical method for spatially resolved and reversible chemical modification of a graphene monolayer. A tightly focused laser on graphene under water introduces an sp(3)-type chemical defect by photo-oxidation. The spa-type defects can be reversibly restored to sp(2) carbon centers by the same laser with higher intensity. The photoreduction occurs due to laser-induced local heating on the graphene. These optical methods combined with a laser direct writing technique allow photowriting and erasing of a well-defined chemical pattern on a graphene canvas with a spatial resolution of about 300 nm. The pattern is visualized by Raman mapping with the same excitation laser, enabling an optical read-out of the chemical information on the graphene. Here, we successfully demonstrate all-optical Write/Read-out/Erase of chemical functionalization patterns on graphene by simply adjusting the one-color laser intensity. The all-optical method enables flexible and efficient tailoring of physicochemical properties in nanoscale for future applications.

Automated summary

We present a facile all-optical method for spatially resolved and reversible chemical modification of a graphene monolayer. By using a tightly focused laser under water, sp(3)-type chemical defects can be introduced by photo-oxidation, and then reversibly restored to sp(2) carbon centers by a higher intensity laser through photoreduction induced by local heating. These optical methods, combined with laser direct writing technique, allow photowriting and erasing of well-defined chemical patterns on graphene with a spatial resolution of about 300 nm. The pattern can be visualized and optically read out by Raman mapping with the same excitation laser. We demonstrate the all-optical Write/Read-out/Erase of chemical functionalization patterns on graphene simply by adjusting the one-color laser intensity. This all-optical method enables flexible and efficient tailoring of physicochemical properties at the nanoscale for future applications.