Fast reduction of electron-beam-activated graphene oxide by an infrared laser pulse

TL;DR

This study demonstrates a rapid, controllable method for reducing graphene oxide using a combined electron-beam-assisted NIR laser process, achieving 90% reduction within 960 ns.

Contribution

It introduces a synergistic electron-beam and NIR laser technique for fast reduction of GO, revealing the role of electron beam-induced defects in enhancing photoreduction.

Findings

90% reduction of GO in 960 ns

Electron beam irradiation creates defects that enhance NIR absorption

Localized restoration of sp2 bonding observed

Abstract

Rapid and controllable reduction of graphene oxide (GO) remains a critical challenge for realizing its full technological potential. Here, we report efficient reduction of GO by a synergistic electron-beam-assisted single-pulse near-infrared (NIR) laser process. Time-resolved electron energy-loss spectroscopy measured with a dynamic transmission electron microscope (DTEM) is used to locally track the oxygen concentration evolution after NIR laser pulse irradiation. This finds an oxygen diffusivity of 1.6 +/- 0.4 x 10$^{-8}$ m$^2$/s, which corresponds to 90% reduction of a 46-nm thick film within 960 ns. Electron beam irradiation is found to change the optical absorptivity of GO in the NIR region and the thermal heating cycle resulting from the laser pulse is simulated. Structural characterization via selected-area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) finds localized restoration of sp$^2$ bonding accompanied by turbostatic disorder in the reduced GO. Together, these results point to a mechanism involving the creation of defects and vacancies produced by electron beam irradiation, which increases the efficiency of NIR light absorption and oxygen diffusion normal to the layers. This study demonstrates the important role of such defects in controlling the photochemistry of GO and its response to NIR illumination.