SolarHyValue · Simultaneous solar hydrogen and value-added product generation by inexpensive photoelectrodes

The role of solar energy and the need for clean fuels (such as hydrogen) is essential in achieving a net zero future. A sustainable way of green hydrogen generation is photoelectrochemical water splitting, which uses only solar energy and water to produce green hydrogen and concomitantly oxygen. This technology, however, with the currently demonstrated efficiencies is not cost-competitive. A less explored application of photoelectrochemical devices is the generation of a value-added oxidation product from abundant polymeric waste materials (e.g., biomass, plastics), instead of the low market value oxygen. Such a device can lead to a reduced energy consumption (compared to water splitting), as well as high market value anodic product. Excitingly, in this approach green hydrogen is generated as a by-product (virtually free) on the cathode. The SolarHyValue project proposes the use of perovskite and organic photoactive layers with a protective sheet to fabricate stable photoelectrodes for simultaneous solar hydrogen and value-added product generation. Efficient bias-free operation of waste valorisation with photoelectrochemical device was only demonstrated with expensive precious metal catalysts (platinum, palladium). The proposed large bandgap caesium lead halide perovskite layer has the potential to enable bias-free, and at the same time efficient photocurrent generation even with the use of solely earth-abundant materials. This will be allowed by the novel device design and the development of a transition metal dichalcogenide (MoS2) catalyst doped at its basal plane with non-precious metal heteroatoms, resulting in excellent catalytic activity. Through increased scientific understanding the SolarHyValue project will lead to the first ever demonstration of a photoelectrochemical device that allows simultaneous, bias-free production of solar hydrogen and value-added product relying solely on inexpensive materials.