Real-time and stepwise deoxidization processes to tune the photoluminescence properties of graphene oxide using EC-SPR spectroscopy.

The development of a stepwise deoxidized process and real-time monitoring of the large-scale mass production of electrochemically reduced graphene oxide (ErGO) sheets are important issues. In this study, we have shown that graphene oxide (GO) sheets can be quantitatively monitored in real-time and controlled in a stepwise manner using electrochemical-surface plasmon resonance (EC-SPR), due to the fact that the oxygen functional groups can be tuned through a deoxidization procedure. The SPR signal can then be detected quantitatively in real-time by changes in the dielectric constant of the GO film during the EC stepwise removal of oxygen functional groups. This is because the refractive index of the GO sheets is affected by the oxygen-containing groups, so that monitoring the SPR angle shift provides a real-time measure of changes in the concentration of the residual oxygen functional groups of the GO sheets. In this study, we demonstrated GO and 100 CV cycles of ErGO at X-ray photoelectron spectroscopy carbon-to-oxygen ratios of 4.1 and 31.57 respectively, and Raman spectra of the D/G intensity ratio of 0.85 and 1.89, respectively. The 100 CV cycles of ErGO at SPR angle shifts were -227.13 mdeg for GO at a concentration of 0.275 mg ml, and -263.47 mdeg for GO at a concentration of 1 mg ml. The photoluminescence emission bands of the GO and the CV 100 cycles of ErGO were 615 to 470 nm. These results may be beneficial for future studies on GO fluorescence characteristics in the field of optoelectronic and biosensor applications.