Pulsed versus continuous-wave Laser deoxygenation of graphene oxide suspensions

Abstract

We report on a comparative study of laser deoxygenation of graphene oxide (GO) suspensions in pure water (pH∼7) using pulsed (nanosecond with wavelength 532 nm and fluence ∼ 0.15 J/cm2) and continuous-wave (CW) (of wavelength 448 nm and power density ∼ 0.25 MW/cm2) lasers at room temperature. Such comparison was not performed previously for GO suspensions. Concentrated GO colloidal suspensions were prepared by a modified Hummer’s method. The presence of oxide groups in GO was proved using X-ray diffraction and Fourier transform infrared (FTIR). The laser deoxygenation processes were verified by means of UV-visible, FTIR and micro-Raman spectroscopies. The impact of changing the laser irradiation time for both lasers has been investigated using the characteristic Raman bands (D and G) of GO as markers to assess the degree of reduction as well as the structural defects of the resulting laser RGO.