Correlation between carbon-oxygen atomic ratio and field emission performance of few-layer reduced graphite oxide

We report the effect of carbon-oxygen atomic ratio (C/O ratio) on the field emission properties of the chemically reduced few-layer graphite oxide (GO). The field emission properties are found to be a non-monotonic function of the C/O ratio in a wide range of 2.06-14.80. Samples with C/O ratio of 6.98 show the lowest turn-on (1.80 MV/m), threshold fields (5.15 MV/m) and much higher current density (44.08 mA/cm2 at 9.00 MV/m). Long-time (10 h) current stability test of the GO at a high current density (∼13 mA/cm2) resulted in the reduction of the GO. The samples with field emission induced reduction show the same non-monotonic effect of the C/O ratio on the field emission properties as that of the chemically reduced GOs. The average current fluctuation of the GO is higher than that of the reduced GO, which is due to the oxygen desorption during the electron emission. The effect of the carbon-oxygen bonds on the surface potential barrier of the reduced GO edges is proposed in detail for interpreting the experimental observations.