▎ 摘　　要

Graphene oxide (GO) was synthesized from graphite through a chemical oxidation process and heat treated at 110 and 220 degrees C in a vacuum atmosphere. The partial reduction and sp(3) to sp(2) phase transition of GO was characterized by powder X-ray diffraction, Fourier-transform infrared, micro Raman, ultraviolet-visible-near infrared spectroscopy techniques. Dielectric properties of pristine GO and heat-treated GO were studied in the frequency range 10(2) to 10(6) Hz at 27 degrees C. Hydroxyl, carboxyl functional groups removed GO after 220 degrees C heat treatment, expressed higher electrical conductivity, dielectric constant and dielectric loss in the order of 10(-2) S m(-1), 10(3) and 10(5) respectively than the pristine GO (10(-6) S m(-1), 10(1) and 10(1)). Pristine and heat-treated GO were coated on the partially cladding removed poly-methyl methacrylate optical fiber and used as fiber optic gas sensors. GO and heat treated GO coated fibers were responsive to detect ammonia, ethanol and methanol vapors from 0 to 500 ppm at 27 degrees C. Sensitivities of GO coated fiber optic sensor were calculated as -0.32, -0.26 and -0.20 counts per ppm for ammonia, ethanol and methanol vapors respectively. The effect of functional groups on dielectric and gas sensing properties of GO was investigated and reported.