Growth of Cu2O Spherical Superstructures on g-C3N4 as Efficient Visible-Light-Driven p-n Heterojunction Photocatalysts for Degrading Various Organic Pollutants

g-C3N4 has been demonstrated as an efficient photocatalyst. To further broaden its photoabsorption range and improve photocatalytic activity, we reported the growth of p-type Cu2O spherical superstructures on n-type g-C3N4 as efficient and stable visible-light-driven photocatalysts. g-C3N4 nanosheets were prepared by calcination-exfoliation, and the growth of Cu2O on g-C3N4 nanosheets was realized by hydrothermal method. Cu2O on g-C3N4 nanosheets are spherical superstructures with diameters of similar to 350 nm, and these superstructures are built from nanoparticles with diameters about 3 similar to 5 nm. g-C3N4-Cu2O heterojunctions exhibit a broad photoabsorption at similar to 525 nm, revealing an obvious red-shift compared with g-C3N4 (similar to 460 nm). Under visible-light irradiation, g-C3N4-Cu2O heterojunctions have stronger photocurrent (similar to 7.2 mu A/cm(2)) than pure g-C3N4 (similar to 3.0 mu A/cm(2)) or Cu2O (similar to 5.1 mu A/cm(2)). Furthermore, g-C3N4-Cu2O heterojunctions exhibit higher photocatalytic activity for degrading rhodamine B (RhB, 92%), tetracycline (TC, 90%) and 4-chlorophenol (4-CP, 82%) after 120 min, which is higher than those by pure Cu2O (32% RhB, 29% TC, 28% 4-CP) and g-C3N4 (46% RhB, 50% TC, 49% 4-CP). The obvious improvement of photocurrent and photocatalytic activity from g-C3N4-Cu2O should be attributed to the broad photoabsorption, the spherical superstructures and the construction of p-n heterojunctions.