Hydrogen production from solar and photoelectrochemical water splitting based on modified nanostructure hematite is investigated for sustainable energy development. Herein, nanorod hematite arrays are prepared by adjusted-hydrothermal method with a diameter of 30 nm. Phosphate group and cobalt ions are deposited on the surface of hematite by chemical immersion process to improve its photoelectrochemical performance and speed up the oxygen evolution reaction in water splitting. The CoPi-modified alpha-Fe2O3 nanorod arrays (NAs) show a greatly enhanced electrochemical and photoelectrochemical property with a photocurrent density 270 mu A cm(-2) at 1.23 V (vs. RHE) for FeCoPi-4 compared with 20 mu A cm(-2) for untreated alpha-Fe2O3 NAs. The effect of phosphate groups and cobalt ions on the alpha-Fe2O3 NAs are both investigated. The Co (II) ion is connected closely with the alpha-Fe2O3 surface through phosphate groups by XPS detection. The phosphate enhances the transport of electron from alpha-Fe2O3 to Co ion. The high performance demonstrated in photoelectrochemical test indicates that CoPi-modified alpha-Fe2O3 NAs is a potential photoelectrocatalyst for water splitting. (C) 2014 Elsevier Ltd. All rights reserved.