Structure-Enhanced Photocatalytic Removal of CrVI by a TiO2 Superstructure with Ultrathin Rutile Nanorods and Abundant {110} Faces

Size and shape, in particular of the external surfaces, are very important factors in determining the photocatalytic activity of TiO2 nanostructures. Here, we demonstrate that the sea-urchin-like rutile superstructure with ultrathin nanorods and exposed {110} faces is an excellent photocatalyst in the removal of CrVI ions from plating wastewater. The superstructure consists of ultrathin rutile nanorods with a specific surface area of 224.4 m2g1; the nanorods have a diameter of several nanometers, and the exposed faces are predominantly {110} faces. This special morphology exhibits a structure-enhanced catalytic activity because it facilitates the transport of photoelectrons to the rutile nanorod {110} faces and prevents them recombining with holes. The rutile superstructure proved excellent at removing chromium from plating wastewater by photocatalytic reduction of CrVI to CrIII in sunlight, and at adsorption of the CrIII ions. The removal effectiveness is nearly 100% at initial Cr concentrations below 53.7 ppm, and the removal capacity can reach about 1000 mgg1 under irradiation by sunlight for 3 hours.