Polymer semiconductors toward efficient photocatalytic H2 production from sea water - understanding and exploiting the presence of ions

Global warming, increasing environmental pollution and limited fossil energy resources push our society to develop a more sustainable production and use of energy. Direct solar hydrogen production with suspended particles by photocatalysis offers an effective solution. However, until now, photocatalytic hydrogen evolution (PHE) suffers from limited efficiencies, is often poorly understood and neglects the practically important sea water environments, where performance typically decreases, but where particle based PHE would be most promising. In this project, we will first study ionic effects, induced by presence of sea water ions, on state of the art polymeric semiconductors systematically. Time resolved spectroscopy will provide fundamental insights into photophysical material properties that are affected by the presence of and interaction with the ions. This activity and property study will focus on hydrophilic donor-acceptor (D-A) structures, which were shown to perform very efficiently in a particle bulk heterojunction (BHJ). Next, we will explore photo-activation processes of polymer materials used for organic electrochemical transistors (OECT), which were shown to enhance the charge stabilization and transport properties upon interacting with sea water ions. By this, we will identify promising material candidates for next generation sea water photocatalysts, which we will study as (BHJ) nanoparticles and optimize toward higher PHE efficiencies in presence of ions. Thereby, this project will provide fundamental insights in ionic effects and their influence on the photocatalytic performance of polymer materials, as well as pathways to tune photophysical properties by ionic interactions. Photo-Iono-Catalysis hence presents an important step to make sea water PHE more viable, while shedding light on the possibility to modify material properties by environmental ionic interactions, which are extendable to many other energy conversion processes.