Improved Water Oxidation of Fe₂O₃/Fe₂TiO₅ Photoanode by Functionalizing with\na Hydrophilic Organic Hole Storage Overlayer

Abstract

The integration of inorganic and\norganic materials has been demonstrated\nas an effective route for photoanodes to yield enhanced photoelectrochemical\n(PEC) water oxidation performance. In this study, we report the preparation\nof an inorganic/organic composite photoanode by depositing 1-hydroxyethylidene-1,1-diphosphonic\nacid (HEDP) onto the surface of an Fe₂O₃/Fe₂TiO₅ heterostructure. It is found that the HEDP\noverlayer as an efficient and highly hydrophilic hole storage layer\ncan effectively promote the surface charge dynamics by facilitating\ncharge transfer and meanwhile by suppressing charge recombination.\nConsequently, the as-fabricated HEDP-Fe₂O₃/Fe₂TiO₅ photoanode exhibits an increased photocurrent\ndensity of 3.10 mA cm^–2 at 1.23 V versus reversible\nhydrogen electrode (RHE) and a significant cathodic shift in the onset\npotential (∼120 mV). Furthermore, after the loading of FeNiOOH\ncocatalyst, a comparable photocurrent density of 3.40 mA cm^–2 at 1.23 V versus RHE accompanied with a lowered onset potential\nare obtained. This work demonstrates an effective route to synthesize\nhighly active hematite photoanodes via organic semiconductor integration.