Holey graphene with enhanced near-infrared absorption: Experimental and DFT study

In this report, we use optical absorption spectroscopy and density functional theory simulations to investigate the optical behavior of a graphitic material with nanoscale holes. The material, produced by heating of graphite oxide in concentrated sulfuric acid followed by annealing at 1000 °C, demonstrated enhanced near-infrared absorption as compared to the pristine graphitic material. The computational study of graphene models containing holes of different sizes and different edge terminations revealed the major interband transitions defining the peaks in the absorption spectra. Our results suggest that the enhancement of near-infrared absorption of the material is caused by electron excitations involving hole edge states. The optical spectrum is strongly dependent on the distance between the holes and almost independent of both hole sizes and the functionalization family.