Operando Studies of Photoactive Metal-Organic Frameworks

The increasing CO2 emission caused by humans contributes significantly to the ongoing climate change. Although, the Paris agreement ambitiously targets the decrease in CO2 concentration in air, current technology is not yet suitable. One strategy to face increasing greenhouse gas emissions is to capture and convert CO2 into fuels or chemical building blocks that can be further used. In fact, this strategy is used by plants: During photosynthesis, the plant takes up CO2 from air and converts it into carbohydrates using only sunlight. The molecules that absorb the sunlight needed for the photosynthesis are called chlorophylls. The drawback of the biological system is that it is constantly decaying and needs to be renewed by the organism. Building on this principle, researchers have singled out the important steps and involved molecules within the photosynthesis and started to mimic them in materials with the same characteristics as their natural model but without decay. So-called metal-organic frameworks are largely studied as artificial plants. Because metal-organic frameworks are the chemists LEGO, molecules with the ability to absorb sunlight can be easily incorporated into a stable material. Within this project, metal-organic frameworks will be synthesised and the underlying mechanism of the conversion of CO2 into value-added chemicals will be studied. To this end, a technique called infrared spectroscopy will be employed that allows to distinguish the generated chemicals and also to determine their amount during the photoreaction. Collecting this information up to every microsecond (for comparison: an eye blink takes about 300 000 microseconds) will help to understand the reaction mechanism. This is important to improve the material and to find an metal-organic framework that converts CO2 in the most efficient way.

The increasing CO2 emission caused by humans contributes significantly to the ongoing climate change. Although, the Paris agreement ambitiously targets the decrease in CO2 concentration in air, current technology is not yet suitable. One strategy to face increasing greenhouse gas emissions is to capture and convert CO2 into fuels or chemical building blocks that can be further used. In fact, this strategy is used by plants: During photosynthesis, the plant takes up CO2 from air and converts it into carbohydrates using only sunlight. The molecules that absorb the sunlight needed for the photosynthesis are called chlorophylls. The drawback of the biological system is that it is constantly decaying and needs to be renewed by the organism. Building on this principle, researchers have singled out the important steps and involved molecules within the photosynthesis and started to mimic them in materials with the same characteristics as their natural model but without decay. So-called metal-organic frameworks are largely studied as "artificial plants". Because metal-organic frameworks are the chemist's LEGO, molecules with the ability to absorb sunlight can be easily incorporated into a stable material. Within this project, metal-organic frameworks will be synthesised and the underlying mechanism of the conversion of CO2 into value-added chemicals will be studied. To this end, a technique called infrared spectroscopy will be employed that allows to distinguish the generated chemicals and also to determine their amount during the photoreaction. Collecting this information up to every microsecond (for comparison: an eye blink takes about 300 000 microseconds) will help to understand the reaction mechanism. This is important to improve the material and to find an metal-organic framework that converts CO2 in the most efficient way.