Employing metal-organic frameworks (MOFs) is a promising approach towards photocatalytic fuel production. These materials bear 3 D crystalline coordination networks, constructed from metal-based nodes and organic linkers resulting in a high porosity and a large surface area, important parameters for efficient heterogeneous catalysis. To explore the utilisation possibilities of MOFs in solar fuel production, we investigate the replacement of the typical Ru-containing photosensitisers, by organic chromophores. So far photosensitisers have been mostly integrated as additive into the host with latter functioning solely as a framework. Developing organic chromophoric molecules that can be directly integrated as linker into the framework would afford light-harvesting, photosensitizing MOF material. Electron transfer from the linker molecules to the catalyst, mimicking the natural photosystem reliance on the cooperation of several hundreds of chromophores, can thus lead to the production of an effective solar energy conversion device.<br/>Here, four new linker molecules based on a chromophoric unit with a push-pull design are synthesised for MOF formation. These molecules display high molar absorption in the visible part of the solar spectrum. Fine-tuned D-A-D architecture was adopted to ensure localisation of the electron density on the acceptor unit. While we took advantage of electron-rich, stable, thiophene-based donor moieties, a variety of well-known electron accepting groups are studied to tune optical and electrochemical properties. The acceptor is further functionalised to anchor a molecular CO<sub>2</sub> reduction catalytic unit and thus promote photoinduced electron transfer from the photosensitizing unit to the catalyst. Some crystalline model-materials have already been successfully synthesised, showing a high absorption in the visible light spectrum. Overall, this work aims for a better understanding of light-harvesting and electron transfer mechanisms in hybrid materials, and subsequent chemical energy conversion processes and fuel production.

Photocatalytic carbon dioxide reduction in metal-organic frameworks based on organic dyes

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.