Graphite powder (300 mesh, purity>95%, XFNANO Materials) or h-BN powder (1 um, purity>98%, Sigma-Aldrich) were dissolved in the urea/glycerol (molar ratio = 2:1) dispersion. After that, 200 mL of the graphite or h-BN dispersion were transferred to a 800 mL flat bottom beaker, under which graphite or h-BN powder were exfoliated and dispersed through mechanical stirring at 800 rpm for 24 h. Then, the obtained products were evenly transferred to a 50 ml centrifuge tube, then centrifuged for 25 min at 5,000 rpm. The top half of the centrifuged graphite or h-BN dispersion were collected and re-dispersed in DMF, followed by filtration and ultrasonic washing with large amounts of DMF and ethanol, and drying in vacuum oven at 60°C. The yield of graphene or h-BN was decided by taking off the mass of the residual solid (Zheng et al., 2018 (link)).
The graphene/DMF and h-BN/DMF dispersion solution were mixed together with a certain mass ratio (the mass content ratio of graphene and h-BN was 1:2, 1:1, 2:1, respectively). The resulting mixed solution was ultrasonic for 30 min, then stirred at room temperature for 24 h and centrifuged at 1,000 rpm for 30 min. The upper liquid was discarded, and the solid precipitation was finally obtained, namely, h-BN/grapheme (BN/G) heterostructure materials.
The graphene/DMF and h-BN/DMF dispersion solution were mixed together with a certain mass ratio (the mass content ratio of graphene and h-BN was 1:2, 1:1, 2:1, respectively). The resulting mixed solution was ultrasonic for 30 min, then stirred at room temperature for 24 h and centrifuged at 1,000 rpm for 30 min. The upper liquid was discarded, and the solid precipitation was finally obtained, namely, h-BN/grapheme (BN/G) heterostructure materials.