We have established a facile and scaleable approach to fabricate tubular graphitic-C₃N₄ using melamine. The construction of the unique tubular morphology is a result of the pre-treatment of melamine with HNO₃. Herein, for the first time, we have explored the electrochemical properties of g-C₃N₄ as an electrode material for supercapacitors. Tubular g-C₃N₄ has significant advantages due to its distinctive morphology, high surface area (182.61 m² g⁻¹) and combination of carbon with nitrogen. Therefore, tubular g-C₃N₄ demonstrated a good specific capacitance of 233 F g⁻¹ at a current density of 0.2 A g⁻¹ in 6 M KOH electrolyte. Furthermore, tubular g-C₃N₄ maintained a high capacitance retention capability (90%) after 1000 cycles. The photocatalytic activity of tubular g-C₃N₄ was evaluated using the organic dyes such as Methylene Blue (MB) and Methylene Orange (MO) under visible light. Tubular g-C₃N₄ demonstrated good photocatalytic activity and enhanced stability compared to bulk g-C₃N₄. The enhanced performance is because of the high surface area, which contains more active sites for reaction. The encouraging performance of tubular g-C₃N₄ in supercapacitors and as a photocatalyst points toward it being a prospective material for energy storage that is environmentally clean.

Well controlled nanosheets-based hierarchical microspheres (NSHMS) of pure covellite phase CuS were synthesized using a facile PVP assisted solvothermal process. The reaction conditions were optimized using various amounts of PVP to develop unique hierarchical structured hollow microspheres. CuS hollow structures have a bandgap of ~1.97 eV. These mesoporous structures exhibit excellent photocatalytic activity in degradation of organic dyes (Methylene Blue) under natural light in comparison to other structures of copper sulphide. These photocatalysts show extraordinary reusability with over 96.5% degradation of organic dye after 6th cycle. A “bottom-up” assembly was successfully developed to synthesize hollow microspheres with unique and well defined architectures at large scale, which offer a good opportunity to understand the fundamental significance of unusual and complex hierarchical structures for their potential applications.