Cobalt Phosphate Group Modified Hematite Nanorod Array As Photoanode for Efficient Solar Water Splitting

Hydrogen production by photoelectrochemical water splitting based on modified nanostructure hematite is investigated for transformation and store of solar energy. Herein, nanorod hematite arrays were prepared by adjusted-hydrothermal method with a diameter of 30 nm. Phosphate group and cobalt ions were deposited of the surface of hematite by chemical immersion process to improve its photoelectrochemical performance and speed up the oxygen revolution reaction in water splitting. The CoPi-modified α-Fe₂O₃ nanorod arrays (NAs) showed a greatly enhanced electrochemical and photoelectrochemical property with a photocurrent density 270 μA/cm² at 1.23V (vs. RHE) for FeCoPi-4 compared with 20 μA/cm² for untreated α-Fe₂O₃ NAs. The effect of phosphate groups and cobalt ions on the α-Fe₂O₃ NAs were both investigated. The Co(Ⅱ) ion is connected closely with the α-Fe₂O₃ surface through phosphate groups by XPS detection. The phosphate enhances the transport of electron from the α-Fe₂O₃ to Co ion. The high performance domanstrated in photoelectrochemical test indicates that CoPi-modified α-Fe₂O₃ NAs is a potential photoelectrocatalyst for water splitting.