Dr. Alexey Cherevan
Title: Photocatalysis for solar fuels: exploring molecular, inorganic, and hybrid photosystems.
Speaker: Dr. Alexey Cherevan.
Institution: Faculty of Technical Chemistry, TU Wien, Austria.
When: 11:30 CET, Monday, September 8th, 2025.
Place: Sala de Grados, Module 8, Faculty of Science, Universidad Autónoma de Madrid.
Due to the ongoing global warming and the upcoming energy crises, the exploitation of alternative, renewable energy sources has become a major focus of materials chemistry. The ultimate solution for sustainable energy lies in the concept of solar fuels – commodity chemicals that can be generated from nothing but sunlight and abundant feedstock through heterogeneous photocatalysis. The reactions of water splitting and carbon dioxide photoreduction, however, involve complex multi-electron redox processes that require a rational design of the surface catalytic sites. When working with ill-defined inorganic surfaces, these sites are inevitably hard to study and understand on a truly fundamental level, which limits the rational synthesis of active and selective photocatalysts.
The field of homogeneous photocatalysis has been evolving independently from its heterogeneous branch, however, it has been much more successful in the purposeful design of organometallic (photo)catalysts assisted by the concepts of coordination chemistry. Molecular photocatalysts, however, face a different set of challenges related to their insufficient redox stability and the need for a molecular photosensitizer required to accomplish the absorption step.
In this talk, I will showcase the work my team has accomplished over the past six years, in which we explored purely heterogeneous (solid-state), purely homogeneous (molecular), and hybrid photosystems for light-driven water splitting. In the first part of the talk, I will introduce you to photocatalysis, discuss its challenges, and give a few relevant examples from our systematic study of earth-abundant transition-metal-based co-catalysts for water oxidation and reduction. I will then look at photocatalysis from the homogeneous perspective and talk about the design of novel polyoxometalate clusters and their light-driven performance toward water-spitting reactions. I will next introduce a hybrid approach that bridges both fields and allows to combine advantages of molecular and solid-state photosystems. As a prime example of this combination, I will showcase the use of fully-inorganic molecular clusters as surface-immobilized co-catalysts for photocatalytic water-splitting reactions. On one hand, I will discuss the covalent attachment of a [Mo3S13]2- thiometalate anion to photoactive surfaces for light-driven hydrogen evolution. On the other hand, I will present an example of linker-mediated electrostatic binding of [Co2W11]7- polyoxometalate onto the TiO2 surface for photocatalytic water oxidation. I will conclude by talking about the future plans and research directions.
