Template-driven synthesis of tin selenide nanosheets and their composites for supercapacitor applications.

Bulk SnSe and SnSe, with direct-band gaps of 1.3 eV and 1.84 eV, are promising materials for optoelectronics, lithium-ion batteries, thermoelectrics, and supercapacitors, due to their excellent electrochemical performance for energy storage. In this context, a new molecular precursor, [MeSn(SeCHN)], has been derived from bis(2-pyrazinyl)diselenide {(2-pyzSe)} and structurally characterised by single crystal X-ray diffraction (sc-XRD) that serves as a building block for the fabrication of tin selenide (SnSe) nanosheets and tin selenide/g-CN composites. The electrochemical performance of the synthesised nanosheets and composites was evaluated for their potential use in supercapacitor applications. The band gaps of rectangular SnSe (1.85 eV) and hexagonal SnSe (2.21 eV) nanosheets, and tin selenide/g-CN composites (1.89 and 1.91 eV) exhibited a blue shift compared to those of bulk SnSe ( = 1.3 eV) and SnSe ( = 1.84 eV). The tin selenide/g-CN composite utilised in supercapacitor applications exhibited a specific capacitance of 140 F g at a current density of 1 A g. Remarkably, it retained 85% of this specific capacitance after 5000 cycles, demonstrating outstanding cycling durability.