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Environmental pollution has become one of the most pressing global challenges of the twenty-first century. Rapid industrial development has significantly increased the release of organic dyes, pharmaceutical residues, and other persistent chemical compounds into water bodies and the atmosphere. Conventional treatment technologies are often unable to completely eliminate these contaminants, allowing them to accumulate in the environment and pose serious risks to ecosystems and human health.

According to researchers, the development of environmentally friendly purification technologies is among the highest priorities of modern science. Particular attention is being given worldwide to photocatalytic materials capable of using solar energy to decompose hazardous organic pollutants without the need for additional chemical reagents or energy-intensive treatment processes.

To address this challenge, researchers at 91��ý Kazakh National University are implementing the scientific project "Development of TiO₂-Based Semiconductor Nanomaterials for the Visible-Light Photocatalytic Degradation of Organic Pollutants."

The primary objective of the project is to develop a new generation of highly efficient photocatalysts capable of operating under visible light. The materials produced within the project are expected to have significant applications in water and air purification technologies, environmental remediation, and renewable energy systems.

Titanium dioxide (TiO₂) is currently one of the most widely used photocatalytic materials due to its excellent chemical stability, corrosion resistance, non-toxicity, and relatively low production cost. Despite these advantages, its practical application remains limited because it is activated primarily by ultraviolet (UV) radiation.

Ultraviolet light accounts for only about five percent of the solar spectrum, whereas nearly forty-five percent of solar energy falls within the visible-light region. Consequently, conventional TiO₂ photocatalysts utilize only a small fraction of available solar energy, significantly limiting their efficiency under natural sunlight.

The KazNU research team proposes an innovative solution to overcome this limitation. Within the project, iron-doped TiO₂ nanomaterials derived from the metal-organic framework MIL-125 will be synthesized. This approach is expected to extend the light absorption range of TiO₂ into the visible spectrum while substantially improving its photocatalytic performance.

The scientific novelty of the project lies in several important aspects.

First, the researchers will synthesize advanced photocatalysts through a multistage solvothermal process followed by iron doping. This method enables precise control over the crystalline structure, pore architecture, and distribution of active catalytic sites, resulting in improved material performance.

Second, the porous structure and exceptionally high specific surface area of the MIL-125 metal-organic framework will be preserved during thermal conversion into TiO₂. This structural feature increases the interaction between pollutants and the catalyst surface, enhancing photocatalytic degradation efficiency.

Another distinctive feature of the project is the comprehensive evaluation of photocatalytic activity using several representative organic pollutants. Model compounds, including Orange II, Rhodamine B, Methylene Blue, and the antibiotic Ciprofloxacin, will be employed to investigate degradation efficiency under visible-light irradiation. These experiments will provide valuable information about the practical applicability of the developed photocatalysts in real environmental conditions.

The researchers will also investigate the fundamental mechanisms responsible for photocatalytic reactions. Using radical scavenger experiments, they will identify the active species involved in pollutant degradation, including photogenerated electrons, holes, and reactive oxygen species. Understanding these reaction pathways will support the optimization of catalyst composition and improve overall photocatalytic performance.

The project employs a comprehensive set of advanced analytical techniques that comply with international standards in materials science and nanotechnology.

The crystal structure of the synthesized materials will be characterized by X-ray diffraction, while scanning electron microscopy will be used to investigate their morphology. Additional characterization techniques include Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller (BET) surface area analysis, electrochemical impedance spectroscopy, and photocurrent measurements. Together, these methods will provide a detailed understanding of the structural, optical, electronic, and surface properties of the developed nanomaterials.

The performance of the photocatalysts will be evaluated through repeated degradation experiments under visible-light irradiation. Their stability, reusability, and long-term photocatalytic activity will also be assessed to determine their suitability for practical environmental applications and large-scale implementation.

Beyond its scientific objectives, the project contributes to strengthening Kazakhstan's position in the international research community. The expected findings will expand fundamental knowledge in photocatalysis, nanotechnology, and advanced functional materials while promoting international scientific collaboration. Research outcomes will be disseminated through publications in high-impact peer-reviewed journals indexed in the Scopus and Web of Science databases.

The practical significance of the project extends well beyond fundamental research. The developed photocatalysts have the potential to be applied in industrial wastewater treatment, air purification systems, environmental remediation technologies, and sustainable solar-energy utilization. Furthermore, the materials may contribute to future developments in photocatalytic hydrogen production through visible-light-driven water splitting, an emerging technology considered essential for the transition to clean energy.

An important advantage of the project is its strong alignment with the principles of sustainable development and the global transition toward a green economy. Photocatalysts capable of efficiently utilizing natural sunlight can significantly reduce energy consumption in environmental treatment processes while minimizing the ecological footprint of industrial activities.

According to the research team, developing visible-light-responsive photocatalysts represents an important step toward the next generation of environmentally friendly technologies. The project is expected not only to advance Kazakhstan's expertise in materials science and photocatalysis but also to contribute to addressing global environmental challenges through innovative scientific solutions.

Ultimately, the project will establish the scientific foundation for the development of internationally competitive photocatalytic materials with broad application potential in environmental protection, renewable energy, and sustainable industrial technologies, reinforcing 91��ý Kazakh National University's contribution to global scientific progress.