Reduction of metal nanoparticle decorated flexible graphene oxide by laser at various temperatures and under selected atmospheres

Abstract

In situ Raman spectroscopy of flexible films of bare graphene oxide (GO) and GO decorated with Pt and Au nanoparticles (NPs) were examined upon exposure to synthetic air and 1% hydrogen in synthetic air. Initially, GO possesses an sp2 rich-structure at room temperature; however, it suffers from a drastic sp2 loss at higher temperatures under argon laser exposure leading to structural damage above 65 °C. Conversely, metal nano particle (MNP) decorated GO undergoes a drastic reduction of sp2 content mainly due to an increased defect density. In MNP composites, the formation rate of reduced graphene oxide (rGO) elevates at higher temperatures leading to an improvement in the sp2 fraction to some extent under argon laser exposure. In fact, the optical properties of MNP decorated GO drastically change against those of bare GO. Despite Pt NPs demonstrating a large catalytic effect with temperature, Au NPs do not. Similarly, the catalytic effect of Pt-GO gives rise to a slight excess in rGO formation in favor of the sp2 domain recovery. Here, there is a dominant temperature effect and a minor catalytic effect during laser exposure to GO.