Effect of chemical etching by sulfuric acid or H2O2–NH3 mixed solution on the photocatalytic activity of rutile TiO2 nanorods

Rutile TiO2 nanorods synthesized by hydrothermal treatment were etched by addition of H2O2–NH3 or H2SO4 solution. The etched rutile TiO2 nanorods were characterized by TEM, SEM, XRD, and specific surface area measurements. New crystal faces were generated on rutile TiO2 nanorods by means of chemical etching. In the case of treatment with H2O2–NH3 solution, the shape of the rutile TiO2 nanorod changed to a sepal-like structure with reaction time. The dissolution of rutile TiO2 nanorod mainly proceeded along [0 0 1] direction. When treated with sulfuric acid, the end [(1 1 1) face] of the rutile TiO2 nanorod was gradually etched. The rutile TiO2 nanorod finally exposed (0 0 1) and (0 2 1) faces during prolonged treatment time. In both cases, rutile TiO2 nanorods were differently etched. The etched rutile TiO2 nanorod showed higher photocatalytic activity for degradation of toluene in gas phase than the original particles