OPUS NCN 2024/53/B/ST5/01028

INTERFACIAL PHOTOELECTROCHEMISTRY FOR MODERN ORGANIC SYNTHESIS

Institute of Organic Chemistry, Polish Academy of Sciences

Katarzyna Rybicka-Jasińska

With respect to sustainable organic chemistry, one of the greenest ways for driving chemical transformations is electrochemistry and photochemistry. Although a number of efforts have brought both of these methods to the forefront in organic chemistry, the focus is mostly on optimizing the efficacy of atom usage: however, by maximizing the atom economy, we are forgetting about maximizing energy efficiency. One way to change that is to take inspiration from biological systems; Nature itself offers sustainability that may and should be an inspiration for us. For decades, natural systems, and in particular photosynthesis, have provided the principal model for solar energy science and engineering. The scientific basis of the photosynthesis process is used, among others, as a model for the development of photovoltaic cells, in which solar energy is converted into electricity. However, such photoelectrochemical cells can work not only for the production of electrical energy but also for the light-powered production of fuels. One can think of it as of a system similar to artificial photosynthesis that could be the way of storage of solar energy for fuel production (hydrogen). Therefore, I postulate that photo-supported electrochemical synthesis is a solution to the problem of energy loss by allowing for dramatic decreases in applied potential as a result of light energy assistance. In typical electrochemical cell each redox process can be constructed as a combination of two half-reactions (cathodic reduction and anodic oxidation) and over the past decade, electrolysis allowed for numerous organic transformations. In regard to sustainability, electrochemistry shows obvious environmental benefits: it allows relatively mild conditions with the elimination of the use of hazardous, toxic, and wasteful oxidants and reductants. However, in electrochemical methods, a high applied potential and a large amount of electrical power are required to achieve the conversion of some organic compounds, sometimes leading to unselective reactions and energy losses. Photo-supported electrochemical synthesis is a solution to these problems allowing for dramatic decreases in applied potentials as a result of light energy assistance. In interfacial photoelectrochemistry (iPEC) a reaction occurs at a semiconducting photoelectrode surface, which under visible-light irradiation generates an electron-hole pair that is used to drive a redox reaction. With the use of the photoelectrode, the use of external power can be avoided or the applied voltage can be decreased to the minimum. As a consequence, the current can be used as a crucial reagent in the catalytic amount, which means that chemical transformation is performed under incredibly mild conditions without energy loss.

The main objective of this research proposal is to set a general paradigm for the design and application of interfacial photoelectrochemical systems (iPECs) for the synthesis of fine organic chemicals and pharmaceutics, where the use of external electric power can be avoided or the applied voltage can be reduced to the minimum (Figure 1). While the utility of this approach is well-known with solar energy conversion (e.g. solar cells), the benefits of its application in organic synthesis are still underexplored. Our efforts will establish new photo-supported electrochemically driven methodologies that will expand the synthetic toolbox for organic chemists providing fine chemicals in a mild, energy-efficient, green, and less-expensive way. In the future, some of the developed systems may share the history of photovoltaics and be widely applied in the industry, increasing the atom economy and energy efficiency.

SONATA NCN 2020/39/D/ST4/01510

PHOTOELECTROCATALYSIS IN PARALLEL, PAIRED ELECTROLYSIS - ZERO-WASTE APPROACH FOR MODERN ORGANIC SYNTHESIS

Institute of Organic Chemistry, Polish Academy of Sciences

Katarzyna Rybicka-Jasińska

To address the sustainability issues of the existing industrial processes for producing fine chemicals, we should develop alternative methods that raise energy efficiency, atom economy, and eliminate toxic chemicals. The recent emergence of renewable energy offers unprecedented access to electricity in environmentally safe manners. It makes electrochemistry, along with photochemistry (considering the abundance of solar light), one of the “greenest” ways for driving chemical transformations. What is more, constructive merging of photo- and electrochemistry offers the potential to overcome the drawbacks of one method through the complementary advantages of the other. Despite that, the potential of photoelectrolysis is still not fully explored – by maximizing atom economy, we are forgetting about maximizing energy efficiency. During classical electrolysis, only one of the two electrodes drives the formation of desirable products, while the other oxidizes (or reduces) sacrificial electron donors (or acceptors), which indisputably leads to losses of energy and materials. Parallel formation of useful intermediates at the two electrodes that are paired to generate the final products, offers an incomparable means for transformative improvements in energy efficiency and atom economy. While the utility of this approach is known with chloralkali electrolysis as one of the classic examples, the benefits of such parallel paired methods for photoelectrocatalysis are still unexplored. The main goal of this project is to set a general paradigm for designing and construction of the paired, parallel photoelectrocatalytic systems, where reactions on both electrodes (cathode, anode) will simultaneously produce highly desirable products in a green and energy efficient way.