(189s) Photophysical Properties of g-C?N?/Biochar Composites in Cyrene: A Green Solvent Alternative for Sustainable Photocatalysis

The development of efficient photocatalysts is crucial for advancing sustainable technologies in environmental applications, such as water purification and solar-driven chemical reactions. Graphitic carbon nitride (g-C₃N₄) has garnered significant attention as a metal-free photocatalyst due to its visible light absorption, thermal stability, and favorable electronic properties. However, its practical application is often limited by challenges such as low surface area, poor charge separation, and aggregation in non-polar solvents, which hinders its photocatalytic performance. To address these issues, composite materials formed by incorporating biochar into g-C₃N₄ have been explored to improve charge separation, increase surface area, and promote structural stability. Biochar, a porous carbon material derived from the pyrolysis of biomass, has gained attention as a sustainable and low-cost material that can enhance the photophysical properties of g-C₃N₄ by providing a platform for electron transfer and facilitating light absorption. However, despite its promising potential, biochar’s effects on g-C₃N₄’s performance in photocatalysis are not yet fully understood.

Moreover, conventional solvents such as dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) are commonly used in the dispersion of g-C₃N₄ for photocatalytic applications. However, these solvents are toxic and non-renewable, raising environmental and health concerns. As such, the search for alternative, greener solvents have become an area of growing interest. Cyrene, a bio-based solvent derived from cellulose, has emerged as a promising alternative to conventional solvents like DMF and NMP. Cyrene exhibits similar physicochemical properties to these toxic solvents while offering a more sustainable, non-toxic, and environmentally friendly option. Its potential as a solvent for photocatalytic systems has not been widely explored, and this work aims to address this gap by investigating the impact of Cyrene on the photophysical properties of g-C₃N₄ and its composites with biochar.

This study primarily aims to evaluate the effect of biochar incorporation on the photophysical properties of g-C₃N₄ and investigate the potential of Cyrene as a green solvent for these composites. g-C₃N₄ was synthesized using three precursor systems: pure melamine (for pristine g-C₃N₄), a melamine–urea mixture (to promote hierarchical structures), and a combination of melamine and biochar (to form g-C₃N₄/biochar composites). The resulting materials were characterized in both powder form and as dispersions in three solvents: Cyrene, DMF, and NMP. The photophysical properties of the materials were evaluated using UV-Vis–NIR spectroscopy, steady-state photoluminescence (PL), and time-correlated single photon counting (TCSPC), which allowed for the analysis of light absorption, emission characteristics, and charge carrier dynamics.

The working hypothesis of this study is that the incorporation of biochar will improve charge separation and enhance the photophysical properties of g-C₃N₄ due to increased surface area and better electron transfer characteristics. Additionally, it is hypothesized that Cyrene could provide similar dispersion and photophysical performance to DMF and NMP due to its similar solvent properties. The study also aims to assess whether the use of Cyrene can provide a more sustainable and eco-friendlier alternative for photocatalytic applications.

Preliminary findings suggest that biochar incorporation has the potential to improve the charge carrier dynamics of g-C₃N₄ composites by facilitating better charge separation. The porous structure of biochar likely enhances the interaction between the material and the solvent, resulting in better dispersion and stability of the composites. Furthermore, it is expected that the inclusion of biochar in g-C₃N₄ will result in a material with more favorable optical properties, such as enhanced light absorption and emission, leading to improved photocatalytic performance.

As for solvent effects, Cyrene has shown promise as an alternative to DMF and NMP, with early observations suggesting it can disperse the composites without compromising their photophysical behavior. The solvent properties of Cyrene, which closely resemble those of DMF and NMP, suggest that it may be an effective green solvent for g-C₃N₄-based photocatalytic materials, offering an environmentally friendly alternative that does not sacrifice performance. Additionally, Cyrene's bio-based and non-toxic nature makes it an attractive option for photocatalytic systems aimed at sustainable chemical processes.

Although the exact results of these comparisons are still under investigation, it is anticipated that Cyrene will provide similar or even superior dispersion and stability of g-C₃N₄/biochar composites compared to conventional solvents. The combination of biochar’s structural enhancements and Cyrene’s green solvent properties could lead to the development of photocatalysts with improved performance and reduced environmental impact, aligning with the principles of green chemistry.

This study represents an important step toward developing sustainable and efficient photocatalysts by demonstrating the potential of biochar as an additive to g-C₃N₄ and Cyrene as a green solvent alternative. The incorporation of biochar is expected to enhance the photocatalytic performance of g-C₃N₄ through improved charge separation, while Cyrene offers a promising, eco-friendly solvent choice for the dispersion of these materials. Further research will focus on the detailed analysis of photocatalytic activity in these green solvent systems and explore their scalability for real-world applications. Ultimately, this work contributes to the growing body of knowledge on sustainable materials and solvents in photocatalysis, paving the way for greener technologies in environmental remediation and solar-driven chemical processes.