Site-selective modification of trivalent iron(III) (Fe3+) ions was applied to rutile titanium(IV) oxide (TiO2) nanorods after chemical etching treatment in order to improve photocatalytic activity under visible-light irradiation. Chemical etching of rutile nanorods with {1 1 0} and {1 1 1} faces using aqueous sulfuric acid (H2SO4) or hydrogen (H2O2)-ammonia (NH3) solution exposed {0 0 1} and {1 1 n} (n < 1) faces, respectively. Fe3+-modified rutile nanorods after chemical etching exhibited higher photocatalytic activity for degradation of toluene in gas phase than that before chemical etching. This improvement of photocatalytic activity was attributed to a large amount of site-selectively-modified Fe3+ ions, resulting in an increase in photoabsorption. Moreover, our results indicate that a rutile nanorod with large {0 0 1} and {1 1 0} exposed crystal faces is the most suitable structure for visible light response by site-selective modification of Fe3+ ions. (c) 2012 Elsevier B.V. All rights reserved.