The anthocyanin coated hematite (α-Fe2O3) photoanode shows highest photoelectrochemical current density among a library of light-harvesting pigments

Abstract

Due to exciton recombination, hematite (α-Fe2O3)-based photoelectrodes are inefficient for water photooxidation. Nanostructuring, doping, and the utilization of photosynthetic proteins and molecular complexes like Photosystem II and I address this. In this work, we validated the influence of Betanin, chlorophyll, and anthocyanin derived from vegetables, flowers, and fruits on bare hematite photoanode photocurrent density. These pigments were deposited atop hematite nanoarchitecture films (HNFs) to construct biophotoelectrodes. Anthocyanin-coated hematite biophotoelectrodes have the highest photocurrent density of isolated pigments, 0.35 mA/cm2. Anthocyanin coating enhances charge transfer due to its antioxidative activity on bare hematite and greater excited state carrier lifetime <τPL> = 3.42 ns. Slow recombination dynamics improve the capacity to inject additional electrons into hematite's conduction band.