Graphene-templated synthesis of C -axis oriented Sb₂Te₃ nanoplates by the microwave-assisted solvothermal method

The successful mechanical exfoliation and chemical synthesis of graphene has attracted considerable attention for the synthesis of other two-dimensional materials on graphene template. Chalcogenide materials such as Sb₂Te₃ are of interest due to the rhombohedral lattice structure with two-dimensional hexagonally closed-packed atomic layers along the c-axis. Here we synthesized c-axis-oriented Sb₂Te₃ nanoplates (NPs) on graphene substrates by the microwave-assisted solvothermal method. The microwave irradiation resulted in a higher temperature of graphene, compared with the synthesis solution, which was revealed by the single-mode microwave experiments and an analytical model based on energy balance and convective heat transfer. Besides, the lattice mismatch between c-axis-oriented Sb₂Te₃ and bridge sites of graphene was only 4%, which is also favorable for the graphene-templated Sb₂Te₃ synthesis. c-Axis-oriented single-crystalline Sb₂Te₃ NPs as large as 7 μm could be successfully synthesized on graphene with negligible damage of the graphene template. Larger surface coverage could be obtained by merging Sb₂Te₃ NPs. The merged Sb₂Te₃ NPs were polycrystalline with rotated grain boundaries. This work provides a facile, rapid, and low-cost synthesis route of c-axis-oriented Sb₂Te₃ NPs on graphene templates, which may be extended for the synthesis of various two-dimensional materials with hexagonally closed-packed atomic layers along the c-axis.