Convenient architectures of Cu2O/SnO2 type II p-n heterojunctions and their application in visible light catalytic degradation of rhodamine B

3D hierarchical heterostructures of p-type Cu2O/n-type SnO2 were synthesized by impregnating porous SnO2 nanospheres with different weight percentages of Cu2O by a simple hydrothermal route. The heterostructures were then evaluated for their photocatalytic performance under visible light irradiation for degradation of rhodamine B (RhB), an organic pollutant. In addition, the effect of varying Cu2O content, and thereby the composition, morphology and photocatalytic activity of the Cu2O/SnO2 nanocomposite were investigated. XRD revealed that the Cu2O/SnO2 nanocomposite comprised of cassiterite tetragonal structured SnO2 and cubic structured Cu2O. HR-TEM and FE-SEM of the as synthesized nanocomposite indicated nearly monodispersed nanospheres with an average size around 60 nm. A UV-vis absorption edge of the Cu2O/SnO2 nanocomposite synthesized in a 1 : 1 ratio was observed at 484 nm (E-g similar to 2.56 eV) that indicated considerable absorption in the visible region of the solar spectrum. An enhancement in photocatalytic activity was observed with an increase in Cu2O impregnation and the complete photo-oxidation of RhB was possible with the 1 : 1 mole ratio Cu2O/SnO2 nanocomposite in 90 min under optimized conditions. Photocatalytic activity of the Cu2O/SnO2 nanocomposite for the degradation of RhB was much higher than that of individual nanoparticles, primarily attributed to the anti-recombination effect of photogenerated electrons and holes at the junction due to formation of p-n heterojunctions. Identification of intermediates and a detailed mechanism of the photo-oxidation process was accomplished by using analytical techniques such as high-performance liquid chromatography [HPLC] and UV-vis diffuse reflectance [DR] spectroscopy.