Columnar Cu nanostructures with tunable lengths are formed directly on porous TiO2 by oblique- angle electron beam evaporation and used as a cocatalyst for photocatalytic conversion of CO2 to methane. A remarkable enhancement in methane production rate is measured using the sculptured copper films with a maximum of 124.3 ppm . cm(-2) . h(-1) for 160 nm long Cu columnar structures under AM 1.5 illumination. This high methane production rate is attributed to a plasmonic enhancement effect due to the columnar Cu nanostructures. (C) 2014 Elsevier B.V. All rights reserved.