fabrication and investigation of highly nitrogen content graphitic carbon nitride (g-c3n5) as a promising cathode for oxygen reduction reaction

With the evolution of civilizations, issues pertaining to insufficient energy supply and detrimental environmental pollutants have emerged as substantial barriers hindering the ongoing growth and prosperity of humankind. since 2017, graphitic carbon nitride (g-c3n5) has garnered significant interest due to its metal-free nature, easy accessibility, excellent physicochemical stability, and appealing electronic band structure. compared with well-known g-c3n4 (sp2 hybridized carbon and nitrogen atoms with triazine moiety), g-c3n5 (with a combined triazole and triazine framework) contains an ultra-high n content (62.5 at%), even higher than that of g-c3n4 (57.1 at%). a prominent factor contributing to the enhancement of g-c3n5's utility lies in its exceptionally high nitrogen content, which significantly improves its oxygen reduction reaction (orr) activity 1. this property renders g-c3n5 particularly suitable for applications in fuel cells, metal-air batteries, and solar cells—all integral components of sustainable energy solutions. the ease with which o2 interacts with g-c3n5 originates from the increased positivity of the carbon atoms resulting from the incorporation of nitrogen. this phenomenon allows for straightforward adsorption of molecular oxygen onto the surface of g-c3n5, thus fostering favorable interactions and optimal conditions for efficient charge transfer processes 2. the triazole moiety present in carbon nitride is thought to cause exceptional physicochemical properties, including an increased number of electrons involved in π-π conjugation and a greater number of pyrrolic n sites compared to triazine or heptazine-based n-rich carbon nitride systems. these properties are believed to be advantageous for oxygen reduction reaction (orr) activities, making triazole-containing g-c3n5 and its composites more effective in orr processes than their counterparts without triazole moieties 3.