Ultrafast Spectroscopy Study Of Graphene Oxide

Graphene oxide (GO) and their nanocomposites possess excellentphotophysical properties, which have been applied in a variety ofscientific fields, especially, as a novel cocatalyst in photocatalyst. Owingto the improvement of charge separation/transfer, which is probablyrelevant to the electronic structure of GO and its reduced derivatives, it issignificant to effectively indicate the band gap of GO in these compoundphotocatalysts. Here, we discussed the relationship of the differentoxygen content and electronic structure of GO by transient absorptionspectroscopy and X-ray photoelectron spectroscopy. We found that GOsamples with the oxygen content of~35%were still “insulators”. But itbegan to exhibit semiconductor-like properties when the oxygen contentslightly decreased to~34%. Moreover, the band gap of thesesemiconductor-like GO samples would not continue red-shift as furtherreduction of oxygen content. Instead, it became a semimetal-like material.Thus,in the experiment insulator-semiconductor-semimetal transition inGO was directly observed from transient absorption spectroscopy.