麻豆淫院

Photocatalysts are powerful materials that use light as a source of energy for operation, becoming indispensable materials in many fields, from the food and biomedical industry to energy production. They are mainly composed of metal-based compounds like oxides, sulfides, etc., but despite their high effectiveness, with time they will become waste.

Fortunately, among the many compounds that exhibit semiconductor properties, some do not contain metal. These are organic compounds containing heteroatoms and possessing a unique structure. One of them is graphitic carbon nitride, also called carbon nitride (CN), which is simply based on carbon and nitrogen forming a polymeric structure.

This metal-free semiconductor offers high chemical stability and low activation energy suitable for its use in solar-driven processes. However, it is not free from limitations such as rapid recombination of photogenerated charge carriers, meaning that the energy absorbed from light is waste.

Another one is the limited number of surface-active sites resulting in poor charge mobility through the whole structure of photoactive material under the photocatalytic process. Therefore, disadvantages like ineffective electron transfer and recombination of generated charge carriers worsen the effectiveness of the photostimulated reactions.

To address these issues, defect engineering that focuses on increasing the number of structural defects in the material and thus increasing the surface area throughout the whole volume has been actively and widely explored as an effective strategy to improve the efficacy of the photocatalyst.

in Chemical Communications, recent work demonstrated by researchers led by Prof. Juan Carlos Colmenares from the Institute of 麻豆淫院ical Chemistry, Polish Academy of Sciences introduced structural defects into the CN polymeric material that forms a complex framework to enhance its photocatalytic performance. They presented a simple and effective bottom-up approach by co-polymerization of two triazine-based monomers such as 2,4,6-triamino-1,3,5-triazine and 4-diamino-6-phenyl-1,3,5-triazine by the thermal polymerization method.

They used a phenyl-containing monomer as the capping agent that partially terminates the polymerization. It leads to disorders in the structure resulting in the formation of defects in the CN framework. The generation of structural defects during synthesis shows a significant simplification over traditional approaches in which defects are made post-synthesis in another step, usually using harsh chemicals and heat.

Now, researchers show a much faster, simpler, and smarter way to reach highly defective structures differently from the beginning. Synthesized defective CN (d-CN) exhibits several advantageous properties. Compared to non-defective CN, d-CN has a much larger specific surface area, reaching 134 m虏 g鈦宦� that is more than the area of the classical badminton court or a very comfortable 5-member family apartment in just one gram.

The d-CN is also full of nanosized pores, also called mesopores, meaning that the material is "spongy" improving reactant access to the surface of the catalyst during the reaction. In pristine CN, most charges generated under the illumination (photoexcitation) are trapped and immobilized.

Here, fabricated d-CN has a higher density of active sites that is crucial for desired photoconductivity and photocatalytic performance. Structural defects, in particular, disruption of regular interlayer stacking and increased interlayer spacing in the polymeric material, significantly enhance the separation and transport of photo-generated charge carriers. Thanks to that, they can move freely along the polymeric structure, instead of getting stuck.

"Creating defects appears to be a promising approach for enhancing charge separation. This raises the question of what drives charge separation in d-CN, given the similarity of carbon nitrides to conjugated polymers, particularly their low dielectric constant, localized excited states, and tendency to trap electrons deeply," says prof. Colmenares.

The d-CN outperformed all previously reported CN-based photocatalysts in hydrogen peroxide generation (H鈧侽鈧�)鈥攁n alternative fuel an important oxidant also called green oxidant used in the fine chemistry industry that commercially requires the application of environmentally harmful chemicals to be produced. The yield obtained using d-CN was more than six times higher than the best alternatives.

Importantly, the material works more effectively than pristine CN under mild, sustainable conditions without aggressive oxidants and organic solvents, operating just in the water and exposed to the 0.45 W LED light source in the visible range at room temperature.

Thanks to the metal-free photocatalyst, it is possible to produce from contaminated water fuels and valuable chemicals at the same time purifying with water, and from benzyl alcohol used in the cellulose industry, among others, it is possible to produce benzaldehyde, which in turn is used in the pharmaceutical industry, food industry, and beyond (fragrance production etc.) and also hydrogen H₂ and/or H₂O₂.

Importantly, the selectivity of the photocatalytic reaction was nearly 100%, showing tremendous precision in the process. These industries are significant, and many chemicals rely on are high-value and expensive to produce. By offering a clean, selective, and low-cost route to important chemicals like benzaldehyde, d-CN offers high potential in photocatalysis and economical production costs in these sectors.

Prof. Colmenares remarks, "By modifying the precursor composition to graft phenyl groups, defects were introduced into CN, leading to increased mesoporosity, improved charge separation, and extended light absorption. The d-CN showed higher efficiency in H₂O₂ production coupled with selective oxidation.

"Enhanced surface area, reactive sites, and charge mobility were achieved after creating the defective structure. d-CN facilitates a two-electron ORR pathway, leading to efficient H₂O₂ production. These findings demonstrate a simple yet effective strategy for increasing performance."

The defective CN demonstrates superior photocatalytic performance, highlighting its potential in energy conversion and environmental applications such as water splitting and pollutant degradation. The defects generation directly during synthesis saves energy, avoids waste, and opens the door to environmental remediation, especially in wastewater treatment.

The beauty of the demonstrated breakthrough lies in its duality, where defected material can degrade water pollution and generate energy, and the simplicity of using green energy without harsh conditions. The novel dual-mode approach shows its potential in environmental remediation, all for a more sustainable future.