Facile synthesis of SiO2@CuxO@TiO2 heterostructures for catalytic reductions of 4-nitrophenol and 2-nitroaniline organic pollutants

Herein, we designed the p-type CuxO (x = 1 or 2) nanoparticles deposited on SiO2 spherical particle inside and coated with thin layered n-type TiO2 semiconductors outside for reduction purpose. The composite material, abbreviated as SiO2@CuxO@TiO2, was characterized. The catalytic performance of the composite was tested for the reductions of 4-nitrophenol (4-NP) and 2-nitroaniline (2-NA). Complete reductions of 4-NP and 2-NA took, 210 and 150 s, respectively. The catalytic efficiency of the composite material may be associated with electron and hole separation resulted from the p-n junction formation between p-type CuxO and n-type TiO2 and the built-in electric field. Moreover, the hydride ion and electrons released from NaBH4 together with outward electrons from n-type TiO2, synergistically, are also responsible for the reduction of nitro aromatic compounds. Our design of composite material from low-priced metal oxides was successful towards reduction of nitro-aromatic compounds.