Photodynamic Bactericidal Agents Based on Single-Atom Photocatalysts

Pathogen contamination of water is an important public health threat around the world. This project will develop a low-cost and highly effective method to disinfect water., The research will create new single-atom photocatalysts (SAPs) that work as powerful antimicrobial agents under light. The SAPs are metal atoms spread out at the atomic level onto a supporting material. The interactions between the metal and the support improve light absorption and charge separation, which boost their ability to kill microbes. The research will use laboratory experiments and computer simulations to explore different transition metals that bond with nitrogen or oxygen atoms in the support material. Along with scientific discovery, this project will provide strong learning experiences to help train the next generation of STEM professionals. The research will also be integrated into several educational outreach programs. Infection by waterborne pathogenic microorganisms poses a significant threat to human and environmental health. Development of effective technologies for water disinfection is of both fundamental and technological significance in environmental remediation. The proposed research is focused on the rational design and engineering of carbon-supported single (metal) atom nanocomposites as high-performance photodynamic antimicrobial agents, a critical step in environmental cleanup through the elimination of waterborne pathogens. In these single-atom photocatalysts (SAPs), the metal centers are embedded within the supporting substrates by strong coordination bonds. The metal-support interactions can be exploited as a unique powerful variable in the manipulation of the materials' optical and electronic properties, leading to optimal photodynamic activity. The project will focus on three tasks and three unique SAPs: (a) atomic dispersion of select transition-metal species within nitrogen-doped carbon scaffold, where the photodynamic performance will be systematically examined within the context of metal-nitrogen coordination interactions; (b) structural engineering of metal oxide nanoparticle-supported single atom catalysts for enhanced photocatalytic bactericidal performance, by taking advantage of the formation of new electronic states within the oxide bandgap, such that the photodynamic activity can be enhanced and extended to the visible range; and (c) select doping of the B sites of perovskite-type ABO3 metal oxide nanoparticle for enhanced photodynamic performance due to manipulation of the electronic band structures. The materials' structures will be meticulously examined by state-of-the art microscopy and spectroscopy measurements and carefully correlated to the bactericidal activity in conjunction with first principles calculations. The ultimate goal is to establish an unambiguous structure-property-activity framework within which the antimicrobial performance of the SAPs can be manipulated and optimized. The proposed research will offer a unique educational framework that helps nurture the next-generation STEM workforce. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.