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Ohemeng, Peter Osei

University of British Columbia

The use of carbon nitride (CNₓ) as a standard organic photocatalyst for solar energy conversion reactions has gained notable attention within the catalysis field. This interest stems from its simple synthesis, visible light-driven photocatalytic performance, and good stability. However, significant challenges remain in fully realizing the material's potential in photocatalytic applications. Chief among these challenges include the poor dispersibility of CNₓ particles in water, limited understanding of its surface and interfacial properties, and the lack of comprehensive structure-property-activity relationships. This thesis addresses these gaps by first reviewing the surface properties and reactivity of CNₓ. It then presents experimental efforts aimed at optimizing CNₓ synthesis and interfacial properties for improved photocatalytic applications. Using a copolymerization approach with neat melamine and methylated melamine (Melₘₑₜₕ), modified CNₓ samples were synthesized, demonstrating enhanced water dispersibility and photocatalytic activity. The best-performing sample showed a three-fold improvement in sacrificial hydrogen (H₂) photoproduction, and rhodamine B (RhB) dye degradation compared to benchmark CNₓ. Further investigations were conducted by preparing additional samples under varied conditions to explore the impact of synthesis methods on their structural and opto-electronic properties. The properties of these samples as well as their activity values were analyzed using machine learning (ML) models and graphical assessments (GA), which revealed that while structure-activity relationships in CNₓ are complex, certain post-synthetic properties strongly correlate with photocatalytic activity. Given the growing concern over arsenic (As) contamination and its detrimental effects on human health, the optimized CNₓ sample from the series of samples was also tested for arsenic remediation. The introduction of methyl groups improved CNₓ’s photocatalytic and adsorptive capabilities for removing arsenic species from water. The sample, labeled CNₓ₅₀, demonstrated high photocatalytic conversion of As(III) to As(V), outperforming the standard CNₓ in arsenic remediation. In summary, this study highlights CNₓ’s dual potential in solar energy conversion and environmental remediation, offering valuable insights for future development of photocatalytic materials.

Text

2024-09-26

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89303

Chemistry

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/