The production of alternative fuels, and protection of our living environment are two of the most intensively studied topics. Efficient generation of fossil-free fuels at low cost requires the development of new materials and implementation of novel methodologies. On the other hand, cleaning of hazardous substances from waste gasses and air requires ecofriendly technologies. In this project we will tackle both issues simultaneously, by developing fully functional photoelectrochemical systems that degrade organic pollutants in waste gas on one side of the device (photo anode), while producing hydrogen gas on the other side (cathode). Where the oxygen evolution reaction is often the bottleneck in standard photoelectrochemical water splitting, here this issue is circumvented by using organic pollutants as electron donors, that are more easily oxidized than water. The driving force behind the entire process is direct sunlight. Therefore, firstly more solar-responsive photo anode materials will be prepared. After rigorous characterization and screening of the photo-activity, these catalysts are integrated in a fully functional photoelectrochemical test setup, that will enable to deduce all relevant intrinsic kinetic and mass transfer parameters. The latter are used as the input of a multiphysics computational fluid dynamics (CFD) model that will enable to improve the overall process operation and the photoelectrochemical cell design in a convenient way and at low cost. Eventually, based on the outcome of the CFD study a laboratory scale demonstration unit will be constructed to showcase the application potential of this multi-purpose sunlight-driven technology.