By Eiman Mohammad; Scavolini Vancouver
This comprehensive review provides scientific insights into the design, synthesis, and application of high-performance g-C3N4-based materials, highlighting their potential to address urgent global challenges in energy sustainability and environmental stewardship.
The study details the synthesis of modified carbon nitride with enhanced photocatalytic activity through facile polymerization, employing a self-assembly method with melamine-cyanuric acid supermolecules regulated by CQDs as precursors. The resulting photocatalysts (PCN@mCQDs-2) underwent rigorous characterization, with their photocatalytic performance assessed in degradation experiments involving DCF and other PPCPs. The investigation elucidates the photocatalytic degradation pathways and mechanisms of diclofenac, alongside evaluations of toxicity reduction, mineralization efficiency, and the reusability of PCN@mCQDs-2. The findings offer promising insights into advancing g-C3N4 materials for effective environmental remediation.
Carbon quantum dots (CQDs), a class of carbon-based nanomaterials, are characterized by non-toxicity, high biocompatibility, facile preparation, excellent electron transport properties, and distinctive up-conversion luminescence properties. Integration of CQDs with semiconductors such as g-C3N4 has been explored to enhance carrier separation efficiency and extend the absorption spectrum. Typically introduced post-g-C3N4 synthesis, potential interactions during precursor stages remain an intriguing area for further exploration. With abundant amino, hydroxyl, and carboxyl groups, CQDs may participate in supramolecular self-assembly via hydrogen bonding, influencing microstructure control, band structure adjustment, and enhancing photocatalytic performance.
Various technologies have been employed for trapping or degrading diclofenac (DCF), including adsorption, ozonation, photocatalytic degradation, Fenton-like processes, photo-electrocatalytic degradation, and bioremediation. Among these, photocatalysis has emerged as highly promising due to its efficacy in degrading and mineralizing recalcitrant pollutants, coupled with environmental sustainability.
Synthesis Strategies and Characteristics: The review encompasses diverse self-assembly methodologies employed alongside corresponding synthesis strategies, investigating how factors such as molecular structure, solution environment, synthesis techniques, and additives influence self-assembly behavior and final material characteristics.
Recent Developments and Mechanisms: Recent advances are detailed, focusing on novel synthesis mechanisms and their implications. These innovations enhance the efficacy and versatility of g-C3N4-based materials in energy conversion and environmental remediation.
Applications in Environment and Energy: Emphasis is placed on practical applications, particularly in pollutant mitigation such as diclofenac (DCF) from water sources. The synthesized photocatalyst PCN@mCQDs-2, derived from melamine-cyanuric acid supermolecules regulated by CQDs as precursors, exhibits exceptional photocatalytic activity under visible light. PCN@mCQDs-2 demonstrates approximately a 25-fold enhancement in DCF degradation efficiency compared to pristine g-C3N4, primarily due to heightened photogenerated hole generation efficiency.
Future Directions: The review outlines future research directions aimed at further enhancing the performance and scalability of these materials. Key areas include exploring novel synthesis methodologies, optimizing material properties for specific applications, and evaluating environmental impact and sustainability metrics.
Graphitic carbon nitride (g-C3N4) represents a notable metal-free photocatalyst with a graphite-like structure and an optimal band gap of 2.7 eV. It offers exceptional chemical stability, a significant surface area, tunable electronic band structures, and excellent visible light responsiveness. Composed of abundant elements, g-C3N4 is economically viable and environmentally benign, making it ideal for applications such as pharmaceutical and personal care product (PPCP) removal from aqueous solutions.
Despite these advantages, g-C3N4 faces challenges such as low electrical conductivity, limited carrier diffusion, and rapid charge carrier recombination. To overcome these limitations and enhance photocatalytic performance, a range of strategies has been explored, including surface modifications, element doping, defect engineering, morphology control, construction of heterojunctions, and supramolecular self-assembly. Supramolecular self-assembly, involving the spontaneous formation of ordered structures via weak interactions between precursor molecules, significantly enhances g-C3N4 photocatalysts. This approach exposes additional active sites, narrows the bandgap, improves electrical conductivity, enhances photogenerated carrier separation efficiency, and amplifies light absorption capabilities.
