Photoactive Mo6 Clusters/Semiconductors Nanocomposites for Sustainable Water Remediation

© EIG Concert Japan
  • Dr. Kaplan Kirakci - Institute of Inorganic Chemistry of the Czech Academy of Sciences - Czech Republic
  • Prof. Yoshiyuki Sugahara - Waseda University, Faculty of Science and Engineering - Japan
  • Dr. Régis Guégan - CNRS-Université d’Orléans - France
  • Dr. Fabien Grasset - CNRS–Saint-Gobain–NIMS - France
  • Dr. Marta Feliz - Instituto de Tecnologia Química, Universitat Politécnica de Valencia - Spain

Water pollution, caused by chemicals and microorganisms, poses a significant threat to water quality and human health. It presently claims more lives than war and violence combined, while the sources of clean water are depleting due to climate change-induced factors and increasing pollution from fertilizers and pesticides. As a result, water purification is becoming economically unviable or impossible, leading to a potential drinking water crisis. Therefore, there is an urgent need to find cost-effective and sustainable solutions for water remediation. Promising sustainable strategies for removing water pollutants include photocatalytic degradation of harmful chemicals and photosensitized inactivation of pathogens. These methods rely on the production of reactive oxygen species (ROS) such as singlet oxygen, superoxide, or hydroxyl radicals when materials are exposed to ultraviolet or visible-light irradiation. ROS are short-lived, and the degradation products of pollutants are generally less toxic, making this approach safer than the use of chemical agents like chlorine derivatives.

Additionally, photoinactivation of pathogens by materials that generate ROS upon visible-light irradiation can overcome the challenges posed by multidrug-resistant microbial pathogens, as ROS target critical components of microbial cells, reducing the likelihood of resistance development. Multicomponent systems or nanocomposites offer attractive designs for photoactive systems in environmental applications, as they enable synergistic effects between their building blocks. A highly efficient process involves photoinduced electron transfer from a dye to the conduction band of semiconducting nanoparticles (nSC), resulting in the formation of ROS, primarily superoxide or hydroxyl radicals, through electron injection from the nSC to molecular oxygen.

Such systems combine the dye’s extended visible-light absorption, allowing the use of sunlight as an irradiation source, with the efficient ROS production by the nSC, leading to enhanced photocatalytic or photoinactivation properties. Octahedral molybdenum cluster complexes (Mo6) are appealing visible-light-activatable phosphorescent dyes for designing these systems. Compared to organic dyes, Mo6 complexes are less prone to selfquenching of luminescent properties at high concentrations and display low photobleaching, which can limit the efficiency and robustness of derived materials. Moreover, Mo6 complexes have low toxicity and are prepared inexpensively, making them ideal candidates for dye-sensitized ROS-producing systems in environmental applications.

The PHOTOMOS-H2O project aims to develop nanocomposite materials based on Mo6 clusters and nSC in
the form of colloids, films, and nanofibrous membranes for the degradation of harmful chemicals and photoinactivation of pathogenic bacteria using visible light, offering an environmentally friendly and energyefficient approach to water treatment.

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