Large-scale and rapid synthesis of disk-shaped and nano-sized graphene

Abstract

We synthesized disk-shaped and nano-sized graphene (DSNG) though a novel ion-exchange methodology. This new methodology is achieved by constructing metal ion/ion-exchange resin framework. The morphology and size of the graphene can be modulated by changing the mass ratio of the carbon-containing resin to the cobalt-containing precursor. This is the first time to show that the DSNG formed on the granular transition metal substrate. The DSNG gives a high intensity of photoluminescence at near-UV wavelength of 311 nm which may provide a new type of fluorescence for applications in laser devices, ultraviolet detector UV-shielding agent and energy technology. The emission intensity of the DSNG is thirty times higher than that of the commercial large graphene. Our approach for graphene growth is conveniently controllable, easy to scale-up and the DSNG shows superior luminescent properties as compared to conventional large graphene.

Figure 1. Schematic view of the approach for disk-shaped and nano-sized graphene (DSNG) growth.

Figure 2. Microscopic images of DSNG.

(a). The tapping mode AFM image of the disk-shaped nano-sized graphene (DSNG) prepared at mass ratio of CoCl₂·6H₂O to D113 resin (R_Co/R) of 0.1, (b). a close-up of DSNG, (c). SEM micrograph of DSNG and (d). high resolution SEM micrograph of a DSNG.

Figure 3. Raman and XPS spectra of DSNG.

(a). Comparison of Raman spectra of DSNG (red line) and highly oriented pyrolytic graphite (HOPG) (blue line) at 514 nm, (b). the 2D band in the Raman spectrum obtained from DSNG is formed by one Lorentzian peak, and the HOPG is formed by a two-peak line shape, (c). comparison of XPS spectra of DSNG (red line) and HOPG (blue line) and (d). high-resolution C1s XPS spectra of DSNG (red line) and HOPG (blue line).

Figure 4. AFM images of the gaphene samples.

The tapping mode AFM images of the graphene samples deposited on new-delaminated mica at ambient condition as a function of mass ratio of CoCl₂·6H₂O to D113 resin: (a). R_Co/R = 0.2, (b). R_Co/R = 0.5 and (c). R_Co/R = 1. The a₁–c₁ are the height profiles along the blue lines in (a–c). respectively.

Figure 5. AFM images of DSNG.

(a). The tapping mode AFM image of the Co/graphene before acid treatment (R_Co/R = 0.1) and (b). the tapping mode AFM image of DSNG after acid treatment (R_Co/R = 0.1).

Figure 6. PL spectra of DSNG.

(a). PLE spectra of the DSNG (R_Co/R = 0.1) and large-area graphene with the detection wavelength of 311 nm and (b). PL spectra of the DSNG (R_Co/R = 0.1) and large-area graphene excited at 270 nm, (c). PL spectra of the nanographene samples with different R_Co/R and (d). the relationship between the normalized PL intensity and the R_Co/R.