Semiconducting Synthetic Melanin‐Based Organic/Inorganic Hybrid Photoanodes for Solar Water Oxidation

: We report the development of semiconducting melanin-based organic/inorganic hybrid photoanodes for solar water oxidation. Synthetic melanin thin-film incorporating polyoxometalate (POM) water oxidation catalysts (WOCs) are readily deposited on the surface of various n-type inorganic semiconductors (e.g., Fe2 O3 , BiVO4 , and TiO2 ) by electropolymerization. The deposition of melanin and POM hybrid (MP) thin-film results in the remarkably improved performance of an underlying semiconductor photoanode for solar water oxidation with a significantly increased photocurrent density and decreased onset potential for water oxidation through the formation of a melanin-based p-n heterojunction structure. We believe that this study can provide insights into the design and fabrication of various melanin-based optoelectronic devices by utilizing its unique physicochemical properties.