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.

Catalysts for oxygen and hydrogen evolution reactions (OER/HER) are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co₃O₄ embedded in tubular nanostructures of graphitic carbon nitride (GCN) and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co₃O₄ and GCN resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co₃O₄@GCN tubular nanostructured (TNS) hybrid exhibited the lowest overpotential (0.12 V) and excellent current density (147 mA/cm²) in OER, better than benchmarks IrO₂ and RuO₂, and with superior durability in alkaline media. Furthermore, the Co₃O₄@GCN TNS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co₃O₄@GCN TNS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

The aim of this literature review was to provide essential information about a plant which is known to everyone as a beverage. In this study we collected particular information about the tea, such as its history, botanical classification, types, extraction methodologies, plant morphology, its active constituents and uses as medicine. Every aspect was elaborated briefly with essence of easy understanding. Special consideration was given to antioxidant potential of the tea and mechanisms by which it acts as antioxidant. At the end, some suggestions for further expanding of the research were defined. Key words: Tea, flavonoids, Epigallocatechin gallate (EGCG), antioxidant.