Boosting Photoelectrochemical Water Oxidation of Hematite by Surface States Modification
61 Pages Posted: 5 Feb 2019 Publication Status: Review CompleteMore...
State-of-the-art water-oxidation catalysts in acidic electrolyte usually contain expensive noble metals such as ruthenium and iridium. However, they are exceedingly expensive to be implemented broadly in semiconductor photoanodes for affordable photoelectrochemical (PEC) water splitting devices. Here, an Earth-abundant CoFe Prussian blue analogue (CoFe-PBA) is incorporated with core-shell Fe2O3Fe2TiO5 type II heterojunction nanowires as composite photoanodes for PEC water splitting. Those deliver a stable photocurrent of 1.25 mA cm-2 at 1.23 V vs. reversible reference electrode in acidic electrolyte (pH=1). The enhancement arises from the synergic behavior between the successive decoration of the hematite surface with nanolayers of Fe2TiO5 and then, CoFe-PBA. The underlying physical mechanism of performance enhancement through formation of the Fe2O3Fe2TiO5 CoFe-PBA heterostructure reveals that the surface states electronic levels of hematite were modified such that an interfacial charge transfer becomes kinetically favorable. These ﬁndings open new pathways for the future design of cheap and efficient hematite-based photoanodes.
Keywords: Photoelectrochemical (PEC) water splitting, hematite, surface states, Fe2TiO5, CoFe Prussian blue analogue, photoanodes, water oxidation, nanowires, acidic electrolyte
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