Research

(gemeinsam mit Prof. Peter Bäuerle, Uni Ulm)External link

Project A2 aims at the synthesis, characterization, and application of a series of molecu-larly defined, noble metal-free, and highly catalytically active water reduction catalysts for the photo- and photoelectrocatalytic hydrogen evolution reaction (HER) under visible light. The novelty and overall goal of the project consists in the development of unique hybrid molecules PS-CAT, which tightly covalently link visible light absorbing photosen-sitizers (PS) and catalytically active metal centres (CAT) allowing for light-induced electron transfer to drive HER. Moreover, the typically used expensive noble metal catalysts and iridium- or ruthenium-based photosensitizers in common HER systems will be substituted by metal-free organic PS and by earth-abundant 3d- and 4d-transition metals (Fe, Mo) as CAT.

The project is firmly based on preliminary work on [FeFe]-complexes, which mimic ca-talytically active centres in natural hydrogenases and as photocatalysts efficiently evolve hydrogen under irradiation and on -conjugated donor–acceptor oligothiophenes, which strongly absorb light in the visible range and have been immobilized on semiconductor electrodes in order to sensitze photoelectrocatalytic hydrogen evolution.

Thus, within project A2 we will build on the two approaches and focus on the deve-lopment of PS-CAT hybrids by tightly linking germole and stannole analogues as PS to diiron complexes as CAT (work package WP1, Jena) and visible light absorbing PS ba-sed on -conjugated thienoacenes (WP2, Ulm). The synthetic work on PS-CAT hybrids will be extended by collaboration with CRC research groups introducing molecular mo-lybdenum sulfide (MoS) complexes as alternative CAT unit (Streb, Ulm, project A5) and rylene-type dyes as alternative PS unit (Peneva, Jena, project A3). In a later phase, the complexity of the oligomer-metal hybrids will be increased by dendritic or conjugated co-polymer structures. In a next step and in collaboration with projects from CRC areas B and C, the most promising catalytically active PS-CAT hybrids will be further func-tionalized to enable their incorporation into heterogeneous supports such as organic soft matrices and electrodes (WP3, Ulm/Jena). The HER activity of the homogeneous and heterogeneous PS-CAT systems under visible light irradiation will be investigated in this and in collaborating projects (WP4, Jena).