Advances in graphitic carbon nitride: a comprehensive review of synthesis, properties, applications and recent developments with photoelectrochemical water splitting

The most promising renewable energy source for the twenty-first century has been hydrogen energy, which has recently taken centre stage in history. Since its development, photocatalytic hydrogen production technology has garnered significant attention as one of the current techniques of manufacturing hydrogen. It is a zero-carbon strategy to produce high calorific value and pollution-free hydrogen energy. One well-known and sustainable photocatalyst that can significantly address urgent environmental and energy-related issues is graphitic carbon nitride (g-C3N4). Graphite-phase carbon nitride (g-C3N4) is an organic semiconductor material that is solely made up of C and N elements. Its physicochemical properties are unmatched by those of conventional inorganic semiconductor materials, and they include easy structural regulation, abundant reserves of cheap raw materials, simple preparation, high mechanical, chemical, and thermal stability, and appropriate energy band positions. In light of this, g-C3N4 has garnered a lot of interest in the field of photocatalytic hydrogen production throughout the past 20 years. This review explores the historical background of g-C3N4, spanning its structure with various morphologies of the prepared g-C3N4 along with its synthesis methods, structural properties, and photoelectrocatalytic mechanisms. Several g-C3N4 synthesis techniques, such as thermal condensation, chemical vapour deposition, solvothermal and hydrothermal, and sol–gel processes, are covered in the first section of the review. In this review, we wrap up the most recent breakthroughs and predicted prospects of g-C3N4 on heterojunction, composite, doping, and other technologies enhancing its capabilities. Particular attention is given to their applications in photoelectrochemical splitting of water. The article also looks at the other uses of g-C3N4, such as environmental cleanup, energy storage, photocatalysis, and sensors. Along with addressing issues like quantum efficiency and charge carrier recombination, a look ahead at new developments is provided. The review offers a thorough overview of the present status of research on graphitic carbon nitride and emphasizes its prospective applications in materials science, energy, environmental science, photoelectrochemistry, and photoelectronic devices. This paper presents g-C3N4 as a promising tool for a more sustainable future and concludes by calling it a sustainable game-changer in the field of energy and environmental technologies.