We report a relatively simple and economical approach for mass production of Cu@CuI mesh. This novel core-shell structure is CuI-coated Cu mesh, fabricated by one-step insitu iodination of commercial copper mesh at an ambient temperature. Such a Cu@CuI mesh is low-cost and can be successfully used for the degradation of soluble organic pollutants in water under UV light. The novel 3D Cu@CuI core-shell structure allows for high electron/hole separation and thus leads to high catalytic efficiency. Rhodamine B (RhB) is fully degraded in even just 6 minutes using a Cu@CuI mesh as the photocatalyst. Unlike the currently reported photocatalysts mostly in the form of powders, nanoparticles, and/or nanowires, the 3D Cu@CuI mesh is freestanding and flexible, and therefore is easily separated from water after photocatalysis without causing secondary pollution. This is a significant advance toward tackling the expansive separation issue of the conventional catalysts, because the ultra-simple separation process of 3D Cu@CuI mesh can facilitate its industry application. With a fantastic combination of low cost, facile and green fabrication, high catalytic efficiency and easy separation 3D architecture, the Cu@CuI mesh may serve as a promising candidate for water purification.