Preparation of reduced graphene oxide by infrared irradiation induced photothermal reduction.

We present a green and scalable route toward the formation of reduced graphene oxide (r-GO) by photothermal reduction induced by infrared (IR) irradiation, utilizing a bathroom IR lamp as the source of IR light. Thermogravimetric analysis, Raman, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the reduction of r-GO by IR light. Ultraviolet-visible-infrared spectra indicate that adsorption of IR light by original GO films is less than that of UV and visible light; but when GO is exposed to IR light, its adsorption of IR light increases very rapidly with time. The influence of the power density of the IR light on the structure and properties of r-GO was investigated. At high IR power density, the reduction reaction was so fierce that r-GO became highly porous due to the rapid degassing and exfoliation of GO sheets. The r-GO powder revealed good performance as the anode material for lithium ion batteries. At relatively low IR power density, the reduction process was found to be mild but relatively slow. Crack-free and uniform conductive r-GO thin films with a volume conductivity of 1670 S m(-1) were then prepared by two-step IR irradiation, i.e. first at low IR power density and then at high IR power density. Moreover, the r-GO films were also observed to exhibit obvious and reversible IR light-sensing behavior.